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[This tutorial was developed with Photoshop 5 but the info remains useful for more recent versions.]
Introduction
Adobe Photoshop is so dominant in its field that it's become not just a household name, but a verb. If someone says that an image has been "photoshopped", everyone immediately understands that it has been enhanced and generally manipulated on a computer. In this masterclass I'm going to look at the processes involved in a typical Photoshop session by creating a photomontage for commercial CMYK-separated print. In the process I'm going to focus on the many new features of the recent Photoshop 5 release to show you how you can put them to use in your own work.
Colour Management
Before beginning any project it's necessary to create the right environment. Essentially all photo-editing boils down to manipulating the colour values of the pixels in a bitmap grid. To do this successfully, we have to ensure that the colours we see and manipulate on screen and the colours that come out on paper are exactly the colours we want. In other words, we need to set up a colour management strategy. The biggest change in Photoshop 5 is its entirely new colour management system. The good news is that the system has the potential to offer accuracy and consistency across platforms, applications, screen and paper. The bad news is that Adobe has managed to make the system over-complex, difficult to implement and potentially dangerous.
RGB
The first step in any colour management system is to ensure that the colours onscreen are as accurate as possible. All monitors create colours based on the RGB system in which red, green and blue light is mixed. No light at all produces black while maximum RGB values (usually measured in 256 steps) give white. All other colours are produced by mixing different values of these three primaries (hence the 16 million colours available in 24-bit RGB colour = 256 x 256 x 256). The problem is that all monitors have slightly different phosphors and mix them together differently. In other words, without management, the RGB system is "device-dependent" which means that the same values will produce different colours on different devices.
To have any sort of consistency and accuracy, Photoshop needs to know what gamut or colour space your monitor is capable of producing and how it produces it. The first step in colour management is therefore to optimise and calibrate your monitor with Photoshop 5's new Adobe Gamma utility which is installed into your Control Panel. By working through the step-by-step wizard this builds up a profile of how your monitor handles the spread of RGB values and allows you to eliminate any in-built colour cast. This information is saved as an industry-standard ICC profile which is loaded each time Windows restarts.
Before you begin photo-editing you need to calibrate your monitor and choose an RGB working space.
Profiles and Working spaces
By reading the profile Photoshop can now understand how your monitor handles colour which is a big advance. However it still isn. t ideal to work in this colour space as each monitor is only able to show a subset of all possible RGB colours and each monitor will have a different subset. The fundamental shift in Photoshop 5's colour handling is designed to bypass this problem by making it possible to work within an independently-defined and so device-independent RGB working space that is then mapped to each individual monitor.
Sounds great. The first problem is that, for reasons best known to itself, Adobe has chosen as its default the sRGB space which was designed to define the lowest common denominator monitor and so actually cuts down on the working gamut! Because our image is destined for commercial print, this just isn. t good enough so using Photoshop 5's File menu's RGB Settings command I. ll change to the SMPTE-240 M space which Adobe is now recommending as a better solution for pre-press work (see Hot Off The Press box-out).
The second problem is that to handle colour correctly all applications in the workflow now need to know not just the RGB values but the working space which defines them. The Adobe solution is to embed this working space information as a profile in the image itself. This profile can then be read by supporting applications so that they know exactly what colours the RGB values represent. In the future this should offer consistency and accuracy throughout the publishing workflow. The irony is that at the moment with non-supporting applications it does the opposite so that the same SMPTE-240M RGB image will look completely different when viewed in Photoshop as it does when imported into Word. For integration with other applications then a more sensible choice would be the Apple RGB working space, which most closely resembles the way Photoshop 4 handled colour, or to revert to your Monitor RGB space.
CMYK
As we are working solely within Photoshop such considerations aren. t crucial and we can take advantage of a dedicated pre-press working space. The advantage of the SMPTE-240 M option is that it encompasses the widest range of the printable CMYK colour gamut and it. s essential that we think about final print right from the start of our work. The fundamental problem is that colour on paper is created through a completely different system to RGB. Printed colour is instead produced by the CMYK (cyan, magenta, yellow and black) model which is subtractive rather than additive as it is based on mixing ink colours with increasing values of CMY moving to black. Most important of all is the fact that the CMYK gamut is smaller than the RGB gamut. In short, there are many colours that are viewable on screen but won' t print.
The Out of Gamut preview is invaluable for highlighting RGB colours that are unprintable in CMYK.
We clearly need to know what our image will look like long before we get it back from the printers so what do we do? Photoshop lets you convert your image to CMYK mode and work solely in the CMYK space, but doing so at this stage has a number of disadvantages. To begin with your working colour space would immediately be restricted, immediately undoing the benefits of our choice of the wide gamut SMPTE-240 M. Worse, we would have to make final decisions about press and paper before we even started the job and many filters and options would no longer be available. Essentially we would lose flexibility, control and quality and, since CMYK is 32-bit, we would also lose disk-space and time.
All our work will be done in RGB mode then, but Photoshop offers two important commands to help in the process of predicting and controlling our eventual CMYK output. To begin with, it offers a CMYK preview (shortcut Ctrl + Y) which maps all unprintable colours to their nearest printable equivalent and so gives a much better idea of how the image will look on the page. This is very useful, but it. s even more important to see which areas are unprintable so that we can try and bring them safely back into the CMYK fold and so avoid the loss of tonal range and the creation of artefacts from the nearest printable colour. The Out Of Gamut command (shortcut Shift + Ctrl + Y) highlights all non-printable colours with a colour that you specify with the File menu. s Preferences command. Most useful of all is the ability to use both shortcuts when dialogs are open so that you can see the potential CMYK effect of RGB changes before you make them.
Resolution
We're now ready to handle both RGB and CMYK colour, but there' s another factor we have to take into account to be confident of commercial print quality - image resolution. A lot of people assume that with their £200 desktop colour printer offering 1000+ dots per inch (dpi) and photo-setters offering 2000+ dpi that that's the sort of resolution their images will need. The good news is that it's actually the lines per inch (lpi) of your outputting device that determines the desired dpi of your image. The general rule is that your image resolution (dpi) should be 1.5 to 2 times the line screen of your outputting device (lpi). As imagesetters tend to use a line screen of between 133lpi and 150lpi that means we only need a size-for-size resolution of between 200dpi and 300dpi. The bad news is that this still soon mounts up. Creating an RGB A4 page at 300dpi, for example, immediately eats up 25Mb.
Bearing this in mind, we're going to need lots of RAM with 128Mb a minimum for full-page photo-editing. We're also going to need lots of storage not just for the image itself, but for the undo information that Photoshop saves to scratch-disk as you work (see Rewriting History boxout). Finally we're going to have to ensure that our images have the necessary resolution. With an ideal resolution of 300dpi that means that we'd need a 1200dpi scanner to be able to enlarge by a factor of four, for example, to blow up an A6 original print to A3. For poster work, however, where the image is the main focus of the project, it would be well worth getting the transparency professionally scanned.
Photo CDs
Since I need a range of images for compositing - and because PC Pro don't pay me nearly enough . I'm going to choose an alternative route and use stock photography (see Stock Photography article). I'm going to use images from two Corel Professional Photo CDs on the Grand Canyon and Arizona. Each image is provided in Kodak. s Photo CD format (PCD) which allows each image to be converted to a range of formats and five set sizes. The largest of these set sizes is 2048 x 3072 which produces an uncompressed image of about 18Mb. Even working at the lower end of our resolution requirements, at 200dpi, this would only stretch to around 10" by 15" so our final montage after cropping will be limited to A4 and under - fine for magazine work but not for poster work.
I'm finally ready to begin looking at the images. For my main image I want a fairly typical image of the Grand Canyon with strong bold shapes of rock and sky. I also want the image to work with contrasting insets designed to show very different aspects of what Arizona has to offer the visitor. After looking at each of the two hundred images I decided on one with a large solid area of shadow down one side of the image which will be ideal for setting off the insets. There are two immediate problems - the first is that there's too much shadow in the rest of the image and the second is that the vertical shadow is down the left-hand side. Using the marquee tool (shortcut "m") and the Image menu. s Crop command it. s simple to isolate the section of the image we want. Using the Image>Rotate Canvas>Flip Horizontal command we can also flip the image so that the viewer. s eye will travel across to the shadow rather than hit it first.
Colour Correction
Our next step is to colour correct the image. The photo's strength is its three very clear areas of colour, red rock, blue sky and black shadow. However both the rock and sky are rather flat and hazy as they would appear at midday when the sun is fiercest. Using the Image menu's Adjust>Levels command (shortcut "l") it. s possible to see how the RGB values in the image are distributed as a histogram both for the image as a whole and for each of the three red, green and blue components channels. It. s also possible to adjust the tonal range by moving the three triangles under the histogram to control highlights, shadows and midtones. By widening the range of each of the three channels independently the image can be given much more tonal depth. The result I'm looking for is of a much more inviting early evening light.
I could apply this colour correction directly to the image, but the original pixel values would then be changed permanently. I'd much rather give myself as much flexibility as possible by applying the change as an adjustment layer (shortcut Ctrl + click on the New layer icon at the bottom of the Layers palette). The huge advantage of this layer-based approach is that in future you can instantly reduce the effect by lowering the layer. s opacity or even temporarily switch it off by hiding it with the Layer palette options. For absolute control you simply need to double-click on the layer name on the Layer palette and you can fine-tune any setting.
Using an adjustment layer Levels effect it is possible to non-destructively colour correct the image.
Selecting Elements
The use of Levels in this way is fine for a major global correction but I also want finer control. In particular I want to be able to deal individually with the three main areas of the image - the sky, rocks and shadows. To be able to do this I first have to select them. Photoshop 5 offers the perfect tool to isolate the sky with its new magnetic lasso. We don't want sharp edges for our selection so the first thing we must do is double-click on the Magnetic Lasso tool icon to call up the Options palette and make sure that anti-aliasing is on. Using the tool it's then simple to outline the sky as the high level of contrast between the sky and rock means that the border automatically snaps to the edge we are tracing.
Once the selection is made, any editing changes will only affect this area of the image until you deselect it (shortcut Ctrl + D). What we'll do instead is to store the selection so that we can come back to it whenever we want. By clicking on the Save Selection as Channel command in the Channels palette the selection is saved as "Alpha 1". By double-clicking on this we can specify our own more meaningful name. Unfortunately trying to select the shadow on the rock in the same way reveals the magnetic lasso. s limitations as the diffuse edges make tracing difficult. Instead it. s a job for the hue-based magic wand tool (shortcut "w"). Once sky, shadows and rock have been saved as separate channels it's possible to instantly select them simply by Ctrl-clicking on their names in the Channels palette.
We can now deal with the separate elements of the image in turn. Even better we can control them non-destructively since, if we create an adjustment layer with an area of the image selected, Photoshop automatically creates a layer mask to limit the effect to just that area. If I select the rock, for example, I can then create an adjustment layer that will not affect the sky or shadows. Photoshop 5's new Channel Mixer is a good choice for this type of colour correction as it enables me to move detail between each of the three colour channels. As the rock is currently a very uniform and flat red, I can mix in some detail by boosting the green and blue channels. Unfortunately I can't do as much as I would like as the out of gamut warning shows that there is little room for manoeuvre in the CMYK space.
Using the new Channel Mixer command you can blend colour channels.
Managing Layers
Even so I'm happy with what the colour correction has achieved. We have more tonal range, detail and richer colours and a much stronger and more inviting main image as a result. Now it's time to move on to the composition. I've selected five images designed to contrast with the main image both in terms of subject and colour. Because they. re going to be used as insets, I can convert the PCDs to 384 x 256 TIFFs and then colour correct them where necessary just as I did for the main image. To begin compositing I simply open each file, select the entire image (Ctrl + A), copy it (Ctrl +C) and then paste it (Ctrl + V) into the main image. Photoshop automatically adds each image to its own layer which can then be reordered or temporarily hidden with the Layer Palette options.
To be able to move each inset into position the dedicated Move tool (shortcut "v") must be used and, because only the currently selected layer is affected, you must first make sure you. ve selected the right one. To help in this, each layer is shown as a thumbnail but these are too small to distinguish easily so it. s advisable to double-click on the layer and give it its own name. Even then, it. s easy to forget which layer is active and so end up moving the currently selected layer out of position. A very useful trick is the fact that Ctrl-clicking with the Move tool automatically selects the relevant layer of the pixel you click on. By Ctrl-clicking on each inset I can quickly position them over the shadow area without constantly having to turn to the Layers palette.
To ensure that the insets are equally and attractively spaced I can take advantage of another new Photoshop 5 feature. By linking all the inset layers by clicking in the second column of the Layer palette next to each thumbnail, I can then access alignment and distribution commands from the Layer menu. Because all my images are exactly the same size and - by complete chance - the right size, this system works well. A more generally practical scheme is to drag in guides from the rulers to create a grid. The individual layers could then be scaled appropriately with the Free Transform tool (shortcut Ctrl + T) and positioned over the grid. Any overhanging areas of inset could then be masked out and hidden by selecting the desired area with the Marquee tool and selecting the Layer> Add Layer Mask> Reveal Selection command.
By linking imported layers you can align and distribute them evenly.
Layer Effects
Because the insets are set against a dark shadow background they already stand out, but there will be no harm in giving them a little extra lift. By creating a drop shadow or similar effect it. s possible to make it look like the images are floating above the image so giving the illusion of depth. In the past creating such an effect would have involved duplicating layers, applying fills and blurring filters and then positioning by eye. Trying to repeat the same effect consistently would be a nightmare. Now with Photoshop 5's layer effects, the process is simple. Simply select the layer name on the layer palette, right click and select "Effects& ". Then select the type of effect you want . I chose an Outer Glow . and specify the colour, opacity, blur and intensity. Take a note of the settings and you can quickly and consistently apply them to each layer. Even better, if you change your mind in future, simply double-click on the "f" symbol by the layer's name and you can update your settings.
Adding and Controlling Text
With our main image and insets sorted, we're now ready to add text to the composition. Again Photoshop 5 has introduced a major innovation to help maintain our editing flexibility - type layers. In the past all text added to an image was automatically rasterized, that is converted to bitmap pixels. As we. ll see this opened up creative possibilities but it meant that future editing was impossible. Just to change typeface, for example, would have meant starting again from scratch. Now all text is added on its own type layer, indicated by a "T" next to its name on the Layers palette. Just as with layer effects, double-clicking on this symbol calls up the type dialog where text and settings can be changed and automatically updated.
Another big improvement in Photoshop 5's text handling is the ability to apply local formatting. In the past if you wanted to mix typefaces or even point-sizes you had to create separate layers. Now this can be done by selecting the words within the Text dialog and changing settings. The title I initially experimented with, for example, was "Arizona dreaming" and I was able to set up an internal creative tension by formatting the two words very differently. Because all changes are previewed automatically on the image and, since the Move tool is automatically selected when the dialog is open, I was able to experiment with a number of variations exactly as they would appear in situ before making any decision.
With Photoshop 5's new type layers, text can be locally formatted and remains editable.
Eventually I decided to break my text up onto two separate type layers in any case. There were three main reasons for this. The first was that I wanted the main "Arizona" text to line up exactly with the middle inset picture, which was easily achieved with the Free Transform command once the word was on a layer of its own. The second was that I still had a large area of shadow not doing anything which would make the ideal backdrop for a subtitle. The third was that for the main title I wanted to be able to take advantage of Photoshop's blend modes. By choosing an appropriate colour for the text and setting the type layer. s blend mode to "Colour Burn" I was able to have the rock background show through the text. Even better with the Layer options command I was able to control which colours were involved in the blend to make the title break up slightly over the rock.
This interplay between layers and the resulting merging between text and underlying rock is exactly the sort of creative effect that is only possible within a pixel-based environment and Photoshop is the only program that delivers such absolute control. In the past I would almost certainly have chosen to prepare images in Photoshop and turned to a drawing program, such as Corel Draw, to handle the composition and text. Working with Draw would certainly still have been faster and simpler, but the new features in Photoshop 5 now make such compositing possible while the program's unique creative possibilities make the effort worthwhile.
Complete Pixel Control
Indeed in many ways the control offered in Photoshop 5 is now more impressive than that of a drawing package. No-one could say that getting to grips with Photoshop's various image layers, adjustment layers, layer effects, type layers, layer effects and layer masks is easy, but the power and flexibility they offer once you have mastered them is immense. In fact, in my final image, all work apart from the initial cropping and mirroring has been carried out using layer controls of one description or another. This means that by progressively hiding each layer in the composition - by clicking on its eye symbol in the Layers palette - I can return back to the original unaltered image. Using my stored alpha channels I could even reselect the elements of the original and start the whole editing process again.
You'll be relieved to hear that I'm not going to. Instead I'm going to finish the job off by preparing it for print. Currently our image is stored in Photoshop's native PSD file format as this is the only format capable of storing all Photoshop's layer-based information. The universal file image format for print, however, is the TIFF so using the File menu. s Save A Copy (Alt + Ctrl + S) command I'll create a TIFF version. In the process all layer information is automatically flattened and the pixels in the underlying image permanently changed. I can then open this single layer TIFF and apply the one command I've so far held back on. The Unsharp Masking command is only available as a filter and so unlike the adjustment layers permanently alters the current active layer. It works by increasing the colour difference already there between pixels and suddenly brings the image into sharp focus.
Converting to CMYK
Now that all creative work has been done, I'm ready to think about print and converting the image to CMYK ready for professional separation. As we. ve already seen, the RGB and CMYK models are about as different as it. s possible to get, so unfortunately there. s not a simple one-to-one relationship. In particular, in the same way that RGB colour depends ultimately on monitor phosphors and lighting conditions, so CMYK colour depends on ink and paper and these factors have to be taken into account. In Photoshop 5 this is now done through the revamped File> Colour Settings> CMYK Setup command which allows broad choices to be made regarding ink and paper and also offers control over advanced features such as how the black plate is generated. Once all settings are finalised, the image can finally be converted with the Image menu's Mode> CMYK Colour command.
RGB to CMYK conversion depends on parameters such as ink set and paper stock.
Knowing enough to make broad changes between coated and newsprint settings is essential as these have major effects clearly visible in the CMYK and Out of Gamut previews. However, the end user is never going to be able to predict the effect of dot gain or undercolour removal in the same way as the printers themselves. As such, for absolute quality, always discuss appropriate settings with your printer before conversion. An alternative solution, made possible by Photoshop 5's new working space and embedded profile colour management, is to simply hand over your RGB file to let your printer make all settings and create the CMYK file themselves. Before trying this on a serious job, however, make sure that you both know exactly what you are doing and that the system works.
The Future
This shift towards a colour-managed workflow where the average user producing professional print doesn. t need to concern themselves with advanced pre-press issues is clearly the way things are moving. In fact in the long run even the need to explicitly convert images to CMYK is likely to disappear altogether. Many publishing programs can already convert RGB images to CMYK separations on the fly and, by using embedded working space profiles and accurate CMYK outputting profiles, it should be possible to accurately colour manage the entire publishing process from initial scan to final print.
Ultimately, however, there. s no getting around the fact that the professional user producing images for print will always have to build an understanding of CMYK into their work if they want to ensure it is successful. Equally there's no doubt that Photoshop is currently the one program that provides all the production and creative tools necessary to make this possible.
Tom Arah
The Competition
Photoshop might be the industry standard, but for many users it has one inescapable limitation - at a street price of around £400 it. s just too expensive. In fact you can often get your hands on the program - or at least the cut-down LE version - for much less and with a free scanner or printer thrown in thanks to Adobe. s aggressive OEM bundling policy. In any case though you should seriously ask yourself whether you really need, or even want, to be using Photoshop.
This would especially seem to be the case when the latest releases of Paint Shop Pro and Picture Publisher both claim to offer Photoshop-style functionality, including CMYK control, for well under a quarter of the price. Ultimately, however, I would tend to be sceptical about such claims. Being able to convert an image to CMYK is all very well but, as we've seen in the masterclass, there. s a lot more to producing successful professional print than the ultimate conversion. No other program offers Photoshop's minute control over RGB to CMYK conversion together with the ability to preview CMYK or out of gamut colours while working in RGB mode. Likewise none of the budget contenders comes close to offering the same level of creative flexibility through features such as adjustment layers and the history palette.
If you are serious about imaging for commercial print then there is no serious alternative to Photoshop. If you are not producing commercial colour-separated artwork, however, there are plenty of alternatives offering not just better value and ease of use but also their own areas of special functionality.
Macromedia xRes, for example, is essentially a Photoshop clone with a proxy system that allows it to edit huge files in real time. Metacreations Painter takes an artistic approach based on its use of brushes designed to mimic traditional media. The latest 5.5 version also tries to fill the hole left by Photoshop's weakness when it comes to Web imaging, a limitation Adobe has tried to exploit itself with its ImageReady web optimisation program. Ulead's PhotoImpact also majors on web graphics together with a generally more creative approach designed to maximize the impact of its end results. The program that comes closest to Photoshop for professional print handling, but which also recognises the importance of those other areas of bitmap editing, such as natural media brushes, web graphic creation and even video-editing, is Corel PhotoPaint. With its clean and modern interface and integration with Corel's other programs, PhotoPaint is pushing Photoshop hard.
The nearest competition to Photoshop comes from Corel PhotoPaint.
Despite this competition, Photoshop remains the undisputed Rolls Royce of photo-editors thanks to its unrivalled underlying engine. However, if you are just wanting something quick and sporty to run around town in, or are more concerned about petrol consumption, then you would be wise to look elsewhere. You could certainly save yourself a lot of money.
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Don't Believe Your Eyes
In the introduction I said that "to Photoshop" has nowadays become a verb for image manipulation. In fact the word isn' t quite as neutral as that and more often than not it is used to imply manipulation for the purposes of deception. In many ways this project is a typical example. I don't feel too bad as I could point to plenty of other images of the Grand Canyon with rocks and sky of the colour we've ended up with, but the fact is that those colours weren't actually there in the original. More to the point, simply by flipping the image for compositional purposes, I've ensured that you couldn't go to Arizona and actually see the scene exactly as it looks in the image.
The deceptions I've practiced are relatively minor but of course they could easily have been just the beginning. Adding in a rainbow, or striking sunset, or even a waterfall, could all have made the image more attractive and each could have been easily and transparently achieved. The point is that as far as Photoshop is concerned all it is dealing with is a grid of pixel values - there is no underlying truth to the image. In fact with the very first photo-editing command applied to the image, any intrinsic authenticity in the image is immediately and irretrievably lost.
So is there anything that can be done to restore the viewers' trust in what they see? Some photo libraries, such as Corbis, ban all editing of their images and some publications indicate image manipulations in their captions. By putting the word "dreams" in the title I. ve deliberately hinted that all is not necessarily as it seems and so protected myself from being sued by disappointed tourists. Such options aren' t feasible in all cases, however, and not everyone is as honest. Ultimately photo-editing exists and can. t be un-invented so the only way to protect yourself is with a healthy dose of scepticism. Don' t believe your eyes.
Any image is possible to create with Photoshop, the only limit is your imagination.
Rewriting History
Through its various layer-based controls, Photoshop has always offered its users unrivalled bitmap-based flexibility. There was one feature, however, that users were crying out for and which version 5 finally delivered - a multiple undo. Now, as you work on an image, your editing actions are automatically stored. To return to an earlier stage you simply have to click on the relevant command name in the list in the History Palette. The difference this makes to creative freedom is immense as you can experiment knowing that the changes you make aren' t necessarily permanent. Even better, through the History Brush, Photoshop 5 offers arguably the most powerful tool in its entire armoury.
The History Palette automatically stores the last 20 editing actions - memory permitting. You can undo multiple actions instantly simply by clicking on the name of a previous editing state. To ensure that you can return to a particular state use the Snapshot command at the bottom of the palette to store the current editing state as a snapshot at the top of the palette.
You can then experiment with any number of filters and retouching commands to try out effects. If there is a version of the resulting image you like you can store this as a snapshot. You can then swap between the two snapshots to see which you prefer simply by clicking in the History Palette.
If you want features from both snapshots, this is where the History brush comes in. By setting the History Brush option next to the snapshot name in the History palette you can paint the snapshot onto the current image complete with control over transparency and blend mode. In effect you are locally applying the editing changes you made in step 2.
Hot Off The Press
Adobe has responded to the criticism of its implementation of the new colour management system in Photoshop 5 by releasing version 5.02. According to the Adobe web site this offers a new colour management wizard and new defaults, together with the renaming (and so implicit recommendation) of the SMPTE-240M working space as "Adobe RGB (1998)". Perhaps most important of all is the provision of a new 66-page PDF file designed to explain the new colour management system and how to set it up for different work-flows. No apology though for making such a mess of things in the first place.
Other changes include fixes to auto-kerning, better support for the Gamma utility under NT, improved DCS output to enable spot channel output from XPress and support for the latest Illustrator 8 files. More information is available at http://www.adobe.com.
Tom Arah
December 1998
Introduction
Adobe Photoshop is so dominant in its field that it's become not just a household name, but a verb. If someone says that an image has been "photoshopped", everyone immediately understands that it has been enhanced and generally manipulated on a computer. In this masterclass I'm going to look at the processes involved in a typical Photoshop session by creating a photomontage for commercial CMYK-separated print. In the process I'm going to focus on the many new features of the recent Photoshop 5 release to show you how you can put them to use in your own work.
Colour Management
Before beginning any project it's necessary to create the right environment. Essentially all photo-editing boils down to manipulating the colour values of the pixels in a bitmap grid. To do this successfully, we have to ensure that the colours we see and manipulate on screen and the colours that come out on paper are exactly the colours we want. In other words, we need to set up a colour management strategy. The biggest change in Photoshop 5 is its entirely new colour management system. The good news is that the system has the potential to offer accuracy and consistency across platforms, applications, screen and paper. The bad news is that Adobe has managed to make the system over-complex, difficult to implement and potentially dangerous.
RGB
The first step in any colour management system is to ensure that the colours onscreen are as accurate as possible. All monitors create colours based on the RGB system in which red, green and blue light is mixed. No light at all produces black while maximum RGB values (usually measured in 256 steps) give white. All other colours are produced by mixing different values of these three primaries (hence the 16 million colours available in 24-bit RGB colour = 256 x 256 x 256). The problem is that all monitors have slightly different phosphors and mix them together differently. In other words, without management, the RGB system is "device-dependent" which means that the same values will produce different colours on different devices.
To have any sort of consistency and accuracy, Photoshop needs to know what gamut or colour space your monitor is capable of producing and how it produces it. The first step in colour management is therefore to optimise and calibrate your monitor with Photoshop 5's new Adobe Gamma utility which is installed into your Control Panel. By working through the step-by-step wizard this builds up a profile of how your monitor handles the spread of RGB values and allows you to eliminate any in-built colour cast. This information is saved as an industry-standard ICC profile which is loaded each time Windows restarts.
Before you begin photo-editing you need to calibrate your monitor and choose an RGB working space.
Profiles and Working spaces
By reading the profile Photoshop can now understand how your monitor handles colour which is a big advance. However it still isn. t ideal to work in this colour space as each monitor is only able to show a subset of all possible RGB colours and each monitor will have a different subset. The fundamental shift in Photoshop 5's colour handling is designed to bypass this problem by making it possible to work within an independently-defined and so device-independent RGB working space that is then mapped to each individual monitor.
Sounds great. The first problem is that, for reasons best known to itself, Adobe has chosen as its default the sRGB space which was designed to define the lowest common denominator monitor and so actually cuts down on the working gamut! Because our image is destined for commercial print, this just isn. t good enough so using Photoshop 5's File menu's RGB Settings command I. ll change to the SMPTE-240 M space which Adobe is now recommending as a better solution for pre-press work (see Hot Off The Press box-out).
The second problem is that to handle colour correctly all applications in the workflow now need to know not just the RGB values but the working space which defines them. The Adobe solution is to embed this working space information as a profile in the image itself. This profile can then be read by supporting applications so that they know exactly what colours the RGB values represent. In the future this should offer consistency and accuracy throughout the publishing workflow. The irony is that at the moment with non-supporting applications it does the opposite so that the same SMPTE-240M RGB image will look completely different when viewed in Photoshop as it does when imported into Word. For integration with other applications then a more sensible choice would be the Apple RGB working space, which most closely resembles the way Photoshop 4 handled colour, or to revert to your Monitor RGB space.
CMYK
As we are working solely within Photoshop such considerations aren. t crucial and we can take advantage of a dedicated pre-press working space. The advantage of the SMPTE-240 M option is that it encompasses the widest range of the printable CMYK colour gamut and it. s essential that we think about final print right from the start of our work. The fundamental problem is that colour on paper is created through a completely different system to RGB. Printed colour is instead produced by the CMYK (cyan, magenta, yellow and black) model which is subtractive rather than additive as it is based on mixing ink colours with increasing values of CMY moving to black. Most important of all is the fact that the CMYK gamut is smaller than the RGB gamut. In short, there are many colours that are viewable on screen but won' t print.
The Out of Gamut preview is invaluable for highlighting RGB colours that are unprintable in CMYK.
We clearly need to know what our image will look like long before we get it back from the printers so what do we do? Photoshop lets you convert your image to CMYK mode and work solely in the CMYK space, but doing so at this stage has a number of disadvantages. To begin with your working colour space would immediately be restricted, immediately undoing the benefits of our choice of the wide gamut SMPTE-240 M. Worse, we would have to make final decisions about press and paper before we even started the job and many filters and options would no longer be available. Essentially we would lose flexibility, control and quality and, since CMYK is 32-bit, we would also lose disk-space and time.
All our work will be done in RGB mode then, but Photoshop offers two important commands to help in the process of predicting and controlling our eventual CMYK output. To begin with, it offers a CMYK preview (shortcut Ctrl + Y) which maps all unprintable colours to their nearest printable equivalent and so gives a much better idea of how the image will look on the page. This is very useful, but it. s even more important to see which areas are unprintable so that we can try and bring them safely back into the CMYK fold and so avoid the loss of tonal range and the creation of artefacts from the nearest printable colour. The Out Of Gamut command (shortcut Shift + Ctrl + Y) highlights all non-printable colours with a colour that you specify with the File menu. s Preferences command. Most useful of all is the ability to use both shortcuts when dialogs are open so that you can see the potential CMYK effect of RGB changes before you make them.
Resolution
We're now ready to handle both RGB and CMYK colour, but there' s another factor we have to take into account to be confident of commercial print quality - image resolution. A lot of people assume that with their £200 desktop colour printer offering 1000+ dots per inch (dpi) and photo-setters offering 2000+ dpi that that's the sort of resolution their images will need. The good news is that it's actually the lines per inch (lpi) of your outputting device that determines the desired dpi of your image. The general rule is that your image resolution (dpi) should be 1.5 to 2 times the line screen of your outputting device (lpi). As imagesetters tend to use a line screen of between 133lpi and 150lpi that means we only need a size-for-size resolution of between 200dpi and 300dpi. The bad news is that this still soon mounts up. Creating an RGB A4 page at 300dpi, for example, immediately eats up 25Mb.
Bearing this in mind, we're going to need lots of RAM with 128Mb a minimum for full-page photo-editing. We're also going to need lots of storage not just for the image itself, but for the undo information that Photoshop saves to scratch-disk as you work (see Rewriting History boxout). Finally we're going to have to ensure that our images have the necessary resolution. With an ideal resolution of 300dpi that means that we'd need a 1200dpi scanner to be able to enlarge by a factor of four, for example, to blow up an A6 original print to A3. For poster work, however, where the image is the main focus of the project, it would be well worth getting the transparency professionally scanned.
Photo CDs
Since I need a range of images for compositing - and because PC Pro don't pay me nearly enough . I'm going to choose an alternative route and use stock photography (see Stock Photography article). I'm going to use images from two Corel Professional Photo CDs on the Grand Canyon and Arizona. Each image is provided in Kodak. s Photo CD format (PCD) which allows each image to be converted to a range of formats and five set sizes. The largest of these set sizes is 2048 x 3072 which produces an uncompressed image of about 18Mb. Even working at the lower end of our resolution requirements, at 200dpi, this would only stretch to around 10" by 15" so our final montage after cropping will be limited to A4 and under - fine for magazine work but not for poster work.
I'm finally ready to begin looking at the images. For my main image I want a fairly typical image of the Grand Canyon with strong bold shapes of rock and sky. I also want the image to work with contrasting insets designed to show very different aspects of what Arizona has to offer the visitor. After looking at each of the two hundred images I decided on one with a large solid area of shadow down one side of the image which will be ideal for setting off the insets. There are two immediate problems - the first is that there's too much shadow in the rest of the image and the second is that the vertical shadow is down the left-hand side. Using the marquee tool (shortcut "m") and the Image menu. s Crop command it. s simple to isolate the section of the image we want. Using the Image>Rotate Canvas>Flip Horizontal command we can also flip the image so that the viewer. s eye will travel across to the shadow rather than hit it first.
Colour Correction
Our next step is to colour correct the image. The photo's strength is its three very clear areas of colour, red rock, blue sky and black shadow. However both the rock and sky are rather flat and hazy as they would appear at midday when the sun is fiercest. Using the Image menu's Adjust>Levels command (shortcut "l") it. s possible to see how the RGB values in the image are distributed as a histogram both for the image as a whole and for each of the three red, green and blue components channels. It. s also possible to adjust the tonal range by moving the three triangles under the histogram to control highlights, shadows and midtones. By widening the range of each of the three channels independently the image can be given much more tonal depth. The result I'm looking for is of a much more inviting early evening light.
I could apply this colour correction directly to the image, but the original pixel values would then be changed permanently. I'd much rather give myself as much flexibility as possible by applying the change as an adjustment layer (shortcut Ctrl + click on the New layer icon at the bottom of the Layers palette). The huge advantage of this layer-based approach is that in future you can instantly reduce the effect by lowering the layer. s opacity or even temporarily switch it off by hiding it with the Layer palette options. For absolute control you simply need to double-click on the layer name on the Layer palette and you can fine-tune any setting.
Using an adjustment layer Levels effect it is possible to non-destructively colour correct the image.
Selecting Elements
The use of Levels in this way is fine for a major global correction but I also want finer control. In particular I want to be able to deal individually with the three main areas of the image - the sky, rocks and shadows. To be able to do this I first have to select them. Photoshop 5 offers the perfect tool to isolate the sky with its new magnetic lasso. We don't want sharp edges for our selection so the first thing we must do is double-click on the Magnetic Lasso tool icon to call up the Options palette and make sure that anti-aliasing is on. Using the tool it's then simple to outline the sky as the high level of contrast between the sky and rock means that the border automatically snaps to the edge we are tracing.
Once the selection is made, any editing changes will only affect this area of the image until you deselect it (shortcut Ctrl + D). What we'll do instead is to store the selection so that we can come back to it whenever we want. By clicking on the Save Selection as Channel command in the Channels palette the selection is saved as "Alpha 1". By double-clicking on this we can specify our own more meaningful name. Unfortunately trying to select the shadow on the rock in the same way reveals the magnetic lasso. s limitations as the diffuse edges make tracing difficult. Instead it. s a job for the hue-based magic wand tool (shortcut "w"). Once sky, shadows and rock have been saved as separate channels it's possible to instantly select them simply by Ctrl-clicking on their names in the Channels palette.
We can now deal with the separate elements of the image in turn. Even better we can control them non-destructively since, if we create an adjustment layer with an area of the image selected, Photoshop automatically creates a layer mask to limit the effect to just that area. If I select the rock, for example, I can then create an adjustment layer that will not affect the sky or shadows. Photoshop 5's new Channel Mixer is a good choice for this type of colour correction as it enables me to move detail between each of the three colour channels. As the rock is currently a very uniform and flat red, I can mix in some detail by boosting the green and blue channels. Unfortunately I can't do as much as I would like as the out of gamut warning shows that there is little room for manoeuvre in the CMYK space.
Using the new Channel Mixer command you can blend colour channels.
Managing Layers
Even so I'm happy with what the colour correction has achieved. We have more tonal range, detail and richer colours and a much stronger and more inviting main image as a result. Now it's time to move on to the composition. I've selected five images designed to contrast with the main image both in terms of subject and colour. Because they. re going to be used as insets, I can convert the PCDs to 384 x 256 TIFFs and then colour correct them where necessary just as I did for the main image. To begin compositing I simply open each file, select the entire image (Ctrl + A), copy it (Ctrl +C) and then paste it (Ctrl + V) into the main image. Photoshop automatically adds each image to its own layer which can then be reordered or temporarily hidden with the Layer Palette options.
To be able to move each inset into position the dedicated Move tool (shortcut "v") must be used and, because only the currently selected layer is affected, you must first make sure you. ve selected the right one. To help in this, each layer is shown as a thumbnail but these are too small to distinguish easily so it. s advisable to double-click on the layer and give it its own name. Even then, it. s easy to forget which layer is active and so end up moving the currently selected layer out of position. A very useful trick is the fact that Ctrl-clicking with the Move tool automatically selects the relevant layer of the pixel you click on. By Ctrl-clicking on each inset I can quickly position them over the shadow area without constantly having to turn to the Layers palette.
To ensure that the insets are equally and attractively spaced I can take advantage of another new Photoshop 5 feature. By linking all the inset layers by clicking in the second column of the Layer palette next to each thumbnail, I can then access alignment and distribution commands from the Layer menu. Because all my images are exactly the same size and - by complete chance - the right size, this system works well. A more generally practical scheme is to drag in guides from the rulers to create a grid. The individual layers could then be scaled appropriately with the Free Transform tool (shortcut Ctrl + T) and positioned over the grid. Any overhanging areas of inset could then be masked out and hidden by selecting the desired area with the Marquee tool and selecting the Layer> Add Layer Mask> Reveal Selection command.
By linking imported layers you can align and distribute them evenly.
Layer Effects
Because the insets are set against a dark shadow background they already stand out, but there will be no harm in giving them a little extra lift. By creating a drop shadow or similar effect it. s possible to make it look like the images are floating above the image so giving the illusion of depth. In the past creating such an effect would have involved duplicating layers, applying fills and blurring filters and then positioning by eye. Trying to repeat the same effect consistently would be a nightmare. Now with Photoshop 5's layer effects, the process is simple. Simply select the layer name on the layer palette, right click and select "Effects& ". Then select the type of effect you want . I chose an Outer Glow . and specify the colour, opacity, blur and intensity. Take a note of the settings and you can quickly and consistently apply them to each layer. Even better, if you change your mind in future, simply double-click on the "f" symbol by the layer's name and you can update your settings.
Adding and Controlling Text
With our main image and insets sorted, we're now ready to add text to the composition. Again Photoshop 5 has introduced a major innovation to help maintain our editing flexibility - type layers. In the past all text added to an image was automatically rasterized, that is converted to bitmap pixels. As we. ll see this opened up creative possibilities but it meant that future editing was impossible. Just to change typeface, for example, would have meant starting again from scratch. Now all text is added on its own type layer, indicated by a "T" next to its name on the Layers palette. Just as with layer effects, double-clicking on this symbol calls up the type dialog where text and settings can be changed and automatically updated.
Another big improvement in Photoshop 5's text handling is the ability to apply local formatting. In the past if you wanted to mix typefaces or even point-sizes you had to create separate layers. Now this can be done by selecting the words within the Text dialog and changing settings. The title I initially experimented with, for example, was "Arizona dreaming" and I was able to set up an internal creative tension by formatting the two words very differently. Because all changes are previewed automatically on the image and, since the Move tool is automatically selected when the dialog is open, I was able to experiment with a number of variations exactly as they would appear in situ before making any decision.
With Photoshop 5's new type layers, text can be locally formatted and remains editable.
Eventually I decided to break my text up onto two separate type layers in any case. There were three main reasons for this. The first was that I wanted the main "Arizona" text to line up exactly with the middle inset picture, which was easily achieved with the Free Transform command once the word was on a layer of its own. The second was that I still had a large area of shadow not doing anything which would make the ideal backdrop for a subtitle. The third was that for the main title I wanted to be able to take advantage of Photoshop's blend modes. By choosing an appropriate colour for the text and setting the type layer. s blend mode to "Colour Burn" I was able to have the rock background show through the text. Even better with the Layer options command I was able to control which colours were involved in the blend to make the title break up slightly over the rock.
This interplay between layers and the resulting merging between text and underlying rock is exactly the sort of creative effect that is only possible within a pixel-based environment and Photoshop is the only program that delivers such absolute control. In the past I would almost certainly have chosen to prepare images in Photoshop and turned to a drawing program, such as Corel Draw, to handle the composition and text. Working with Draw would certainly still have been faster and simpler, but the new features in Photoshop 5 now make such compositing possible while the program's unique creative possibilities make the effort worthwhile.
Complete Pixel Control
Indeed in many ways the control offered in Photoshop 5 is now more impressive than that of a drawing package. No-one could say that getting to grips with Photoshop's various image layers, adjustment layers, layer effects, type layers, layer effects and layer masks is easy, but the power and flexibility they offer once you have mastered them is immense. In fact, in my final image, all work apart from the initial cropping and mirroring has been carried out using layer controls of one description or another. This means that by progressively hiding each layer in the composition - by clicking on its eye symbol in the Layers palette - I can return back to the original unaltered image. Using my stored alpha channels I could even reselect the elements of the original and start the whole editing process again.
You'll be relieved to hear that I'm not going to. Instead I'm going to finish the job off by preparing it for print. Currently our image is stored in Photoshop's native PSD file format as this is the only format capable of storing all Photoshop's layer-based information. The universal file image format for print, however, is the TIFF so using the File menu. s Save A Copy (Alt + Ctrl + S) command I'll create a TIFF version. In the process all layer information is automatically flattened and the pixels in the underlying image permanently changed. I can then open this single layer TIFF and apply the one command I've so far held back on. The Unsharp Masking command is only available as a filter and so unlike the adjustment layers permanently alters the current active layer. It works by increasing the colour difference already there between pixels and suddenly brings the image into sharp focus.
Converting to CMYK
Now that all creative work has been done, I'm ready to think about print and converting the image to CMYK ready for professional separation. As we. ve already seen, the RGB and CMYK models are about as different as it. s possible to get, so unfortunately there. s not a simple one-to-one relationship. In particular, in the same way that RGB colour depends ultimately on monitor phosphors and lighting conditions, so CMYK colour depends on ink and paper and these factors have to be taken into account. In Photoshop 5 this is now done through the revamped File> Colour Settings> CMYK Setup command which allows broad choices to be made regarding ink and paper and also offers control over advanced features such as how the black plate is generated. Once all settings are finalised, the image can finally be converted with the Image menu's Mode> CMYK Colour command.
RGB to CMYK conversion depends on parameters such as ink set and paper stock.
Knowing enough to make broad changes between coated and newsprint settings is essential as these have major effects clearly visible in the CMYK and Out of Gamut previews. However, the end user is never going to be able to predict the effect of dot gain or undercolour removal in the same way as the printers themselves. As such, for absolute quality, always discuss appropriate settings with your printer before conversion. An alternative solution, made possible by Photoshop 5's new working space and embedded profile colour management, is to simply hand over your RGB file to let your printer make all settings and create the CMYK file themselves. Before trying this on a serious job, however, make sure that you both know exactly what you are doing and that the system works.
The Future
This shift towards a colour-managed workflow where the average user producing professional print doesn. t need to concern themselves with advanced pre-press issues is clearly the way things are moving. In fact in the long run even the need to explicitly convert images to CMYK is likely to disappear altogether. Many publishing programs can already convert RGB images to CMYK separations on the fly and, by using embedded working space profiles and accurate CMYK outputting profiles, it should be possible to accurately colour manage the entire publishing process from initial scan to final print.
Ultimately, however, there. s no getting around the fact that the professional user producing images for print will always have to build an understanding of CMYK into their work if they want to ensure it is successful. Equally there's no doubt that Photoshop is currently the one program that provides all the production and creative tools necessary to make this possible.
Tom Arah
The Competition
Photoshop might be the industry standard, but for many users it has one inescapable limitation - at a street price of around £400 it. s just too expensive. In fact you can often get your hands on the program - or at least the cut-down LE version - for much less and with a free scanner or printer thrown in thanks to Adobe. s aggressive OEM bundling policy. In any case though you should seriously ask yourself whether you really need, or even want, to be using Photoshop.
This would especially seem to be the case when the latest releases of Paint Shop Pro and Picture Publisher both claim to offer Photoshop-style functionality, including CMYK control, for well under a quarter of the price. Ultimately, however, I would tend to be sceptical about such claims. Being able to convert an image to CMYK is all very well but, as we've seen in the masterclass, there. s a lot more to producing successful professional print than the ultimate conversion. No other program offers Photoshop's minute control over RGB to CMYK conversion together with the ability to preview CMYK or out of gamut colours while working in RGB mode. Likewise none of the budget contenders comes close to offering the same level of creative flexibility through features such as adjustment layers and the history palette.
If you are serious about imaging for commercial print then there is no serious alternative to Photoshop. If you are not producing commercial colour-separated artwork, however, there are plenty of alternatives offering not just better value and ease of use but also their own areas of special functionality.
Macromedia xRes, for example, is essentially a Photoshop clone with a proxy system that allows it to edit huge files in real time. Metacreations Painter takes an artistic approach based on its use of brushes designed to mimic traditional media. The latest 5.5 version also tries to fill the hole left by Photoshop's weakness when it comes to Web imaging, a limitation Adobe has tried to exploit itself with its ImageReady web optimisation program. Ulead's PhotoImpact also majors on web graphics together with a generally more creative approach designed to maximize the impact of its end results. The program that comes closest to Photoshop for professional print handling, but which also recognises the importance of those other areas of bitmap editing, such as natural media brushes, web graphic creation and even video-editing, is Corel PhotoPaint. With its clean and modern interface and integration with Corel's other programs, PhotoPaint is pushing Photoshop hard.
The nearest competition to Photoshop comes from Corel PhotoPaint.
Despite this competition, Photoshop remains the undisputed Rolls Royce of photo-editors thanks to its unrivalled underlying engine. However, if you are just wanting something quick and sporty to run around town in, or are more concerned about petrol consumption, then you would be wise to look elsewhere. You could certainly save yourself a lot of money.
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Don't Believe Your Eyes
In the introduction I said that "to Photoshop" has nowadays become a verb for image manipulation. In fact the word isn' t quite as neutral as that and more often than not it is used to imply manipulation for the purposes of deception. In many ways this project is a typical example. I don't feel too bad as I could point to plenty of other images of the Grand Canyon with rocks and sky of the colour we've ended up with, but the fact is that those colours weren't actually there in the original. More to the point, simply by flipping the image for compositional purposes, I've ensured that you couldn't go to Arizona and actually see the scene exactly as it looks in the image.
The deceptions I've practiced are relatively minor but of course they could easily have been just the beginning. Adding in a rainbow, or striking sunset, or even a waterfall, could all have made the image more attractive and each could have been easily and transparently achieved. The point is that as far as Photoshop is concerned all it is dealing with is a grid of pixel values - there is no underlying truth to the image. In fact with the very first photo-editing command applied to the image, any intrinsic authenticity in the image is immediately and irretrievably lost.
So is there anything that can be done to restore the viewers' trust in what they see? Some photo libraries, such as Corbis, ban all editing of their images and some publications indicate image manipulations in their captions. By putting the word "dreams" in the title I. ve deliberately hinted that all is not necessarily as it seems and so protected myself from being sued by disappointed tourists. Such options aren' t feasible in all cases, however, and not everyone is as honest. Ultimately photo-editing exists and can. t be un-invented so the only way to protect yourself is with a healthy dose of scepticism. Don' t believe your eyes.
Any image is possible to create with Photoshop, the only limit is your imagination.
Rewriting History
Through its various layer-based controls, Photoshop has always offered its users unrivalled bitmap-based flexibility. There was one feature, however, that users were crying out for and which version 5 finally delivered - a multiple undo. Now, as you work on an image, your editing actions are automatically stored. To return to an earlier stage you simply have to click on the relevant command name in the list in the History Palette. The difference this makes to creative freedom is immense as you can experiment knowing that the changes you make aren' t necessarily permanent. Even better, through the History Brush, Photoshop 5 offers arguably the most powerful tool in its entire armoury.
The History Palette automatically stores the last 20 editing actions - memory permitting. You can undo multiple actions instantly simply by clicking on the name of a previous editing state. To ensure that you can return to a particular state use the Snapshot command at the bottom of the palette to store the current editing state as a snapshot at the top of the palette.
You can then experiment with any number of filters and retouching commands to try out effects. If there is a version of the resulting image you like you can store this as a snapshot. You can then swap between the two snapshots to see which you prefer simply by clicking in the History Palette.
If you want features from both snapshots, this is where the History brush comes in. By setting the History Brush option next to the snapshot name in the History palette you can paint the snapshot onto the current image complete with control over transparency and blend mode. In effect you are locally applying the editing changes you made in step 2.
Hot Off The Press
Adobe has responded to the criticism of its implementation of the new colour management system in Photoshop 5 by releasing version 5.02. According to the Adobe web site this offers a new colour management wizard and new defaults, together with the renaming (and so implicit recommendation) of the SMPTE-240M working space as "Adobe RGB (1998)". Perhaps most important of all is the provision of a new 66-page PDF file designed to explain the new colour management system and how to set it up for different work-flows. No apology though for making such a mess of things in the first place.
Other changes include fixes to auto-kerning, better support for the Gamma utility under NT, improved DCS output to enable spot channel output from XPress and support for the latest Illustrator 8 files. More information is available at http://www.adobe.com.
Tom Arah
December 1998
