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A Computer Darkroom Essay


Photoshop 5.0, which was launched back in the early summer of 1998, was the first version of Photoshop to offer a truly color managed workflow. At the time it received mixed reviews, some liking the new device-independent color management system and others loathing it, some thought it over complex and others an unnecessary restriction on their preferred way of working. In some respects the reaction was to be expected, after all some folk don't like change. Anyway, I think it's fair to say that for better or worse Photoshop 5.0 changed the way we thought and worked with color at application level.


So, here we are four versions on and Photoshop CS2 (AKA Photoshop 9.0) has its own list of changes. Thankfully the major changes are for the better, which means that few, if any, existing Photoshop users will be too disgruntled.

OK, so the color management system and associated settings have been tweaked a little, but they'll still be familiar to those who have been using versions higher than 7. All of this is good news if you're migrating from these earlier versions. However, color management and particularly the plethora of options associated with it can leave many new users in a state of confusion. Therefore, the content of this essay, is aimed primarily at new Photoshop users. Also, since it's aimed at the newer user, I think it worth taking a few moments to review the underlying principles of color management.

Color Management Primer

Components of a Color Management System

A typical  imaging system will consist of input and output devices, for example: scanners, digital cameras, monitors, and printer. Unfortunately, with such a range of device types, technologies, and gamut limitations, it's inevitable that at least some of them will reproduce the same color differently (i.e. color is device dependent). Obviously, this will present significant problems when working with documents originating from different sources, and will be further complicated when the same document is destined for different types of output device. Therefore, some means of ensuring that color data is reproduced in a predictable way throughout the entire imaging system is essential. This is where the Color Management System (CMS) comes in, and its job is to maintain the consistent and accurate appearance of color on all of the different devices within the imaging system.

A color managed system comprises three basic components, namely: -

  • A device-independent color space - this is usually referred to as the Working or Reference color space.

  • ICC profiles for each device (i.e. printer, scanner, monitor, digital camera, etc.) that accurately describes the color characteristics of the specific device.

  • A Color Matching Module (CMM) that will interpret the information contained within the device profiles and carry out the instructions on how the color characteristics of each device should be treated.

Color Numbers, their Meaning and ICC Profiles

A digital image will usually comprise many millions pixels, each of which is represented by a numeric value. The value assigned to each pixel will describe many attributes but  in this essay it's the color value or mix (e.g. RGB value) that we're most interested in. I have already mentioned that when a color is device-dependent, then the appearance of  pixels with identical values will very often differ. I have also mentioned that this is because each device has its own unique way of translating the raw color value into visual color. This is where the ICC profiles come into play. The ICC profile ensures that discrepancies that result from the widely differing color characteristics of each device are known to the color management system. In simple terms it's the ICC profile that conveys the meaning of the raw color numbers associated with each pixel. If we were discussing spoken language rather than color, then the ICC profile would be synonymous with a translator.

Device profiles come in two basic forms, i.e. Input and Output. Input profiles typically describe the color characteristics of scanners and digital cameras, whereas Output profiles describe devices such as monitors, printers and film recorders. Input profiles are often referred to as one-way since it is only possible to select them as the source meaning we can never convert an document into the color space of our scanner or digital camera. Output profiles are two-way meaning we can convert From or To them.

Consumer class film and flatbed scanner applications have been  ICC aware for some time now, with the vendors usually choosing sRGB as their preferred color space, which is a bit of a misnomer because sRGB is not a device color space. Clearly, these vendors are doing some work behind the scenes so as to keep things simple for the user, which isn't necessarily as good as it might first appear. The sRGB color space isnít generally regarded as appropriate for high quality image editing, especially when print or film output is required. So, to overcome this some vendors also provide the user with the option of choosing from a small selection of alternatives. For example, printer vendors such as Epson provide generic ICC profiles with their Photo class printers, although generally accepted these profiles are rarely as accurate as we would like. Nevertheless, they are getting better with each new generation of printer. As a rule,  truly accurate color matching usually requires customised ICC profiles for each device and/or media type. These ICC profiles can be created professionally or you can buy your own profiling application.

Why bother with Profiles and Color Management?

Even though color correction and color management are not the same thing they're often confused with each other, especially by the novice Photoshop user. Explaining the difference can very often lead to even more confusion, but hopefully the following explanation provides some help.

We have already established that the color characteristics of most imaging devices tend to be unique to that device. Likewise, it's very rare for them to be truly linear (i.e. R=G=B=Neutral). Sometimes this second characteristic is referred to as the device being badly behaved; with scanners and printers being good examples of badly behaved devices. Obviously, it would be extremely difficult to edit a document where a group of pixels with values of R=G=B=128 (i.e. grey) actually appeared on the monitor to be non-neutral. In such circumstances color correction would an absolute nightmare. To overcome these discrepancies we usually carry out all our editing in color spaces that are well behaved or device independent. In Photoshop well behaved color spaces are more usually referred to as the Working Spaces, and are always characterised by RGB values that appear neutral when all three are equal. These Device Independent color spaces do not behave like, nor are they influenced by, any real world device. So, in this respect it could be argued that Working Spaces are based on synthetic color spaces.

So, we have Device Profiles and Working Space Profiles - how do they interact?

The first thing we need to understand is that for them to be useful to the color management system, then both device and working space profiles must confirm with the ICC standard. In fact you'll more often see such profiles referred to as just ICC profiles. Anyway, without the aid of  device profiles the accurate translation of the document color data (the RGB numbers) from the scanner or digital camera into the Working Space will prove very difficult, if not impossible. Likewise, without the aid of accurate media specific printer profiles, the translation from the Working Space into the color space of a digital printer will prove equally difficult. We also need an accurate monitor profile so as to ensure that what we see on the monitor is a true representation of the document color.

The following flow diagram demonstrates a typical imaging workflow, with the document being passed between devices: - from scanner/digital camera - to - computer - to - monitor - and printer.


Typical Imaging System

So, the main benefit offered by color management is that the process of color correction can be undertaken in the knowledge that the document displayed on the monitor is an accurate visual representation of the original subject, and that the final print will accurately reflect the colors of the document being displayed.

Some Photoshop Revision

Photoshop CS2 continues to use document specific color settings, which means that the color space of each document is independent of others that may be open on the Photoshop desktop. As with previous versions of Photoshop the Working Space that's defined in the Color Settings dialog only has a direct bearing on three types of document, viz.: -

  1. New documents

  2. Existing documents without an embedded ICC profile

  3. Imported documents with no embedded ICC profile (i.e. untagged documents), which might include scanned documents or those emanating from digital cameras.

Document specific color means that it's the ICC profile embedded within the document that determines how it will be displayed (it's appearance) and not the default Photoshop Working Space. With Photoshop CS2 you can have multiple documents, each in its own unique Working Space, open at the same time, and each will be displayed accurately. Of course all of this assumes you're using an accurately calibrated and characterised monitor.

Section 1 - Monitor Calibration and Characterisation

Monitor calibration and characterisation (profiling) is probably the most important aspect of a color managed workflow. So, what is calibration, why is it so important, and why is it different from characterisation?

Calibration is a process whereby a device is brought to a standard state (e.g. a color temperature of 6500K and gamma of 2.2), whereas characterising the monitor is the process of determining how the monitor represents or reproduces color . We characterise the monitor by measuring how it displays known color values, then creating an ICC profile. The ICC profile is simply a data file that includes a description of the monitorsí color handling characteristics (i.e. its gamut). The calibration data will also be written into the ICC profile. As I've already mentioned, Photoshop then uses the monitor profile to automatically optimise the display of documents. It does so by carrying out an on-the-fly conversion between your document profile (e.g. ProPhoto RGB, Adobe RGB, sRGB, ColorMatch) and the monitor profile. This conversion does not alter the actual document in any way; just its appearance on the monitor.

Tip: Adobe no longer supply Adobe Gamma with the Mac version of Photoshop. Nevertheless, Mac users can use Apple Display Calibrator Assistant found within System Preferences as an alternative.

To calibrate and characterise the monitor Windows users should open the Adobe Gamma utility or a third party alternative. If you're not already familiar with Adobe Gamma it's a Control Panel utility that can easiest be accessed from My Computer > Control Panel. However, before running Adobe Gamma, it is best that the monitor has been switched on for at least 30 minutes. It is also a good idea to work in subdued lighting when calibrating a monitor, and remember to set the desktop color to grey.

Tip: Adobe Gamma was designed for visual calibration of CRT type monitors and is unlikely to produce satisfactory results with LCD type monitors. If you're using an LCD type display then I recommend that you purchase a hardware based calibration system such as the X-rite Photo iOne Display 2 or Datacolor SpyderPro3.


Windows Control Panel as is appears when using the Classic Theme

Step-by-Step Calibration

Step 1

When the Adobe Gamma utility is first opened you will be asked to make a choice between the Step-by-Step (Wizard) and the Control Panel method. It's probably easier to use the Step-by-Step (Wizard) method.


Step 2

Using the Load button choose your monitor profile or pick one that's close, but if in doubt choose sRGB,.


Before progressing to the next step, be sure to give the profile a unique description and include the date.

Step 3

Set your monitor contrast control to maximum and then adjust the brightness control until the innermost grey square is only just visible against the black surround. Squinting your eyes helps with this process, as does keeping the room lighting at a low level or off.


Step 4 

If you're using a manufacturer supplied profile for your specific make and model of monitor then in all probability the Phosphors will be listed as Custom. If this is the case leave well alone. If you don't have a monitor profile choose either Trinitron or P22-EBU. I keep getting asked -"how do I decide which is appropriate for my monitor?"  You can tell a Trinitron monitor by simply looking at the display area. A Trinitron type monitor will have two faint lines running across the display area approximately 1/4 from the top and 1/4 from the bottom. If your monitor has these lines choose Trinitron, otherwise choose P22-EBU.


Step 5

You should begin by keeping View Single Gamma selected. However, keep in mind that this option ONLY allows you to adjust the relative brightness of the monitor. Adjust the slider until the inner grey square blends with the outer frame, squinting slightly can help. Finally, deselect the View Single Gamma checkbox.


Step 6

This is the step where you neutralise the color imbalances inherent in your monitor. Adjust each of the sliders in turn so as to blend the inner square with its colored surround. Again squinting is a great help. Green is usually the most difficult to get right, but persevere. The closer you get to a perfect match at this point the more accurate your final profile will be.


Step 7

Depending upon your computer type choose either the Windows Default or Mac Default gamma. In reality, this choice is not as important as it once was and you can choose either in the knowledge that Photoshop will make the appropriate corrections when necessary. Personally, and even though most of my work is now done on the Mac platform I choose gamma 2.2


Step 8

Choosing the White Point for your monitor is pretty much a formality these days. Even the die-hards are in agreement that 6500oK is probably the best option on most systems.

You should have already set the Hardware white point via the dials/buttons on the monitor. Most monitors have a native white of 9300oK; so do check what it has been manually set to.

Choosing 6500oK provides the cleanest and brightest white point and closely matches daylight. If you feel really confident you could select the Measure option. You can choose 5000oK, but this usually produces a dimmer and more yellow white point.


Step 9

Generally, it's better to leave the Adjusted White Point setting at the default - Same as Hardware. Nevertheless, this option is used to choose a working white point for monitor if it differs from the hardware white point set in the last step.

By way of example; if your hardware white point can only be set to 6500oK, but you want to set it at 5000oK then simply choose this value as the Adjusted White Point setting. Adobe Gamma will change the monitor display accordingly.  However, choosing this approach will all cause the graphics card color LUT to be adjusted quite severely, and depending upon the graphics card the screen can look quite ugly on some systems. As indicated above, I recommend that you choose Same as Hardware and thus avoid this problem.


Step 10

That's it, if all has gone well you will have adjusted the brightness, contrast and color settings of your monitor to the optimum values.

Make a quick check using the Before and After radio button. If you're happy that the screen display now looks more neutral than before press the Finish button and Save the profile. Once saved the profile will be available for use by the OS and Photoshop.



Section 2 - Photoshop CS2 Color Settings

The Color Settings dialog is the control room for the Photoshop colour management system, and like all control rooms it can appear complicated. Both the dialog layout and default colour settings have changed slightly from previous versions, but the changes are more aesthetic than functional, so I won't dwell on them. If you already  use Photoshop then you'll likely have this dialog configured to meet your needs, and it's probably best that you stick with those settings. On the other hand new users should begin by clicking on the button labelled More Options

The default RGB colour setting depends upon your location but generally you'll find that it's either: North America General Purpose 2 or Europe General Purpose 2. If you're working with documents that are primarily destined for the web then either is perfectly acceptable. However, if you're documents are destined for print then these settings are generally regarded as being less than ideal. So, if the General Purpose 2 settings are not ideal, what is?

I could answer the above question by simply writing "US or Europe Prepress Defaults", but doing so doesn't really help explain why. Therefore, I will work my way through each section of the Color Settings dialog in turn.

Note the box at the bottom of the dialog labelled Description. As the mouse is moved across the various pop-up menus, etc. you should see a short but informative explanation of what each menu does. Also note the button labelled More Options; it's probably best that you select it now, as it will let you see the complete Color Settings dialog rather than the simplified version.


Figure 1 - Photoshop CS2 Default Color Settings

The first section is labelled Settings, and is a simple pop-up menu with a list of preset Photoshop settings plus any that you may have saved previously. You needn't worry too much about this section just yet.


Figure 2

Working Spaces

The next section is labelled Working Spaces (figure 3), and as I discussed earlier the selections made here will determine the Working Space profiles used for colour handling of your documents.


Figure 3 - Default Working Space Profiles

There are four Working Space types in Photoshop: RGB, CMYK, Gray and Spot (occasionally called Modes because they appear under the Image>Mode menu). Since configuring the others follows a similar process I will concentrate on the RGB Working Space.

Also note that the term Working Space should not be confused with Workspace, which is used by Adobe to describe the layout of palettes, menu bars, etc. Working Space relates specifically to the various colour modes available in Photoshop.

RGB - Working Space

Clicking the RGB pop-up menu with the mouse will produce a list of options similar to that shown below (figure 4). In this example I've selected Adobe RGB (1998) as the RGB Working Space. You'll also notice that it appears grouped with three other Working Spaces, these historically being the most popular choices of Photoshop professionals. Typically, sRGB will be confined to situations were the user is solely interested in web design. ColorMatch RGB was once a favoured choice of many Mac users and Apple RGB is apparently for Mac web design.


Figure 4

If you look just above the four common Working Spaces you should also find options for Monitor RGB, and in the case of Mac systems ColorSync RGB. Monitor RGB is the colour space of your monitor as created by the Adobe Gamma utility or a 3rd party software/hardware combination. Generally, it isn't a good idea to use the monitor profile as your Working Space, but it's important that does appear in the list.

It's often claimed that Photoshop CS2 has no obvious way of informing the user which monitor profile is actually being used. Well, a quick check for Monitor RGB in the RGB Working Space pop-up should be enough to put your mind at rest. If Monitor RGB is showing something other than the profile you created when calibrating the monitor it is essential that you investigate the reason and make the appropriate corrections.

The actual list of options available for selection as Working Spaces different according to whether More Options is activate, or not. If you chose to activate More Options then the list of available RGB profiles will be quite extensive.

CMYK - Working Space

Desktop type inkjet printers from Epson, Canon and HP actually require RGB data rather than CMYK, which means that the choice you make for this particular Working Space will have no influence in their actual output. This is the main reason that I leave it set at the default US Web Coated (SWOP) v2, and if using a desktop inkjet, then I suggest that you do likewise.

So, other than the list of available profiles, the procedure for choosing CMYK Working Space isn't that different to RGB. Again, having More Options activated gives you a more extensive list.

Note: the options available to you may not exactly match those shown in the screenshot!


Figure 5

Grayscale - Working Space

With the Grayscale Working Space we have access to two gamma settings, a series of five preset dot gain curves, the ColorSync Gray Work Space (Mac only) and the ability to customise the dot gain to our own requirements. The Gray Gamma 2.2 is probably the best for most users, but feel free to experiment.


Figure 6

Also note, that if you choose to use a Custom Gamma or Dot Gain this will be the Working Space listed in the Gray Working Space pop-up menu.

Another very important point regarding Grayscale is that itís not tied to the CMYK setup! This is why some legacy grayscale documents might not look quite the same as they did in Photoshop 5.x (does anyone still use Photoshop 5?)

Spot - Working Space

The Spot pop-up menu is broadly similar to the grayscale, but for spot colors. The options that we find include a series of five preset Dot Gain options and the facility for customising the Dot Gain curve if required. The screenshot shown below indicates that I've selected 20% Dot Gain version as my default.


Figure 7

Color Management Policies

Color Management Policies was a new phrase introduced by Adobe with Photoshop 6 and continues with only minor changes in Photoshop CS2. Figure 8 below shows the new default setup, but this hides a lot of important information.


Figure 8 - Photoshop CS2 Default Color Management Policies

Based on feedback, this section of the essay is probably the one that causes new Photoshop users greatest difficulty. Nevertheless, it's an important aspect of Photoshop that is better to understand than ignore. Therefore, the explanation that I give below will appear quite wordy.

Basically, each Working Space will have the same set of three policy options, although you need not configure each identically. The Color Management Policies are: -

(a) Off

In simple terms, the Off Policy ensures that Photoshop does as little as possible when dealing with ICC profiles. In most situations it isn't the ideal choice and contrary to popular believe it's certainly not for new users. The following explanation will give you some idea as to the behaviour of Photoshop when this option is selected.

  • Choosing Off will mean that all new documents will be created without an embedded ICC profile. Likewise, when you save them there will be no embedded profile within the document. Generally, documents that do not contain an embedded ICC profile are referred to as being untagged, which invariably means that their color appearance will vary on different  monitors. 

  • Opening an existing document with an embedded ICC profile that matches the current Working Space means that Photoshop will honour the embedded profile, and that this profile will subsequently be saved with the document.

  • The default Pasting behaviour between documents is to retain numerical values (RGB pixel values), not the appearance. This means that no conversion between color spaces will take place and will often lead to the pasted section of the document taking on a radically different appearance to that of the original.

  • Opening an existing document with an embedded ICC profile that does not match the current Working Space (i.e. profile mismatch) will cause that embedded profile to be stripped out of the document. The document will subsequently be saved with no embedded profile. With this policy you'll find that the Ask When Opening warning checkbox is unchecked for Profile Mismatches, so a warning similar to the following (figure 9) will appear.


Figure 9

The problem with this configuration is that the user either accepts what Photoshop dictates or doesn't open the image at all, not much of a choice. Activating the Don't show again checkbox is generally accepted as a good move, and will ensure that you're no longer nagged.

(b) Preserve Embedded Profiles (Default)

For most situations this policy offers the greatest degree of flexibility and therefore my preferred. The following explanation should give you an idea as to the behaviour of Photoshop CS2 when this policy is selected.

  • Choosing Preserve Embedded Profiles means that when you open an existing document into Photoshop, which has an embedded ICC profile that differs from the current Working Space, then that document and its associated profile will be left intact. In other words Photoshop will make no attempt to convert the document to the current Working Space; the original embedded profile will be retained and subsequently saved with the document. Nevertheless, even though the document and Photoshop are no longer in sync, color space wise, the document preview will still be accurate.

  • When opening an existing image with an embedded ICC profile that matches the current Working Space Photoshop will take no action; the image is opened and saved as normal.

  • The default behaviour when pasting either an RGB or Grayscale document is slightly more complex whereby the appearance of the pasted documented will be preserved but the numbers will change (i.e. the pixel values will change). In the case of CMYK it is the numbers that will be retained, not the appearance.

  • If the document being opened or imported has no embedded ICC profile (i.e. the image is untagged) then Photoshop will use the current Working Space for editing and previewing purposes. However, the profile will not be embedded into the document when it is subsequently saved.

  • Creating a new document with this policy setting means that the current Working Space is used for editing, previewing. The associated profile will eventually be embedded into the file when saved. However, the default Working Space profile for new documents can be overridden in the New document dialog.

(c) Convert to Working Space

This policy behaves in an almost identical fashion to color management Photoshop 5. It's for this reason that many still tend to favour it. Actually this policy isn't a bad choice but does need to be treated with care.

  • If an existing image with no embedded ICC profile is opened or imported into Photoshop then the current Working Space will be used for editing and previewing. However, there will be no profile embedded into the image when it is saved (i.e. the resulting image will be untagged).

  • If an image is opened or imported and has an embedded ICC profile which is found to differ from the current Working Space then that image will be converted into, and subsequently saved in the Working Space. When the image and the Working Space are matched then Photoshop takes no action; the image is opened and saved as normal. New documents will be previewed, edited and ultimately saved in the current Working Space.

  • Finally, the default pasting behaviour is to convert and thus preserve the appearance of the document. However, the user will get the option not to convert the pasted image, hence preserving the numbers if the pasted image doesn't match with the target image.

The following warning (figure 10) will appear if the profile warning Ask When Opening has not been activated for Profile Mismatches. Again, my earlier comment about Photoshop imposing its will on proceedings applies. It's worth reading the text and comparing it with figure 9.


Figure 10

At first glance the above warning appears virtually identical to that shown for the OFF Policy, but there is a subtle difference - the document is converted to the Working Space profile rather than discarding the embedded profile. Compare the text of the two screenshots (figure 9 and 10) if you're in any doubt as to the differences. Again you may wish to tick the Don't show again checkbox so as to stop this warning reappearing in the future.

Overriding the Default Policy Behaviour

The previous section described how your choice of Color Management Policy determined the default behaviour of Photoshop CS2 under various scenarios. However, you need not be confined to these preset outcomes. A much better option would be to configure the Color Management Policies as shown in figure 11 below.


Figure 11

Here we can see that each of the checkboxes for Profile Mismatches and Missing Profiles be set for Ask When Opening or Ask When Pasting as appropriate Basically, the three checkboxes associated with the profile warnings have the following impact on the Color Management Policies: -

(i) Profile Mismatches: Ask When Opening

When this checkbox is active Photoshop has been set to present the user with a warning when the image being opened or imported has an embedded profile that does not match the current Working Space. The warning looks like figure 12, and contains three options with the default settings being dependent upon the actual Color Management Policy in operation at the time. Noticed that unlike the examples shown previously, all the necessary information required to make an informed decision is present.


Figure 12

The above example is preset for how the dialog would appear when the Color Management Policy is set for Preserve Embedded Profile. The user can choose to leave the image as is (default - Use the embedded profile), allow the conversion (Convert document's colors to the Working Space) or strip out the embedded profile and switch off color management (Discard the embedded profile). Had the policy been Convert to Working Space the dialog would have looked almost identical except that it would have been preset for Convert document's colors to Working Space. Basically, the answer to the question: How do you want to proceed? is already decided for you when the Embedded Profile Mismatch dialog appears. However, if you know this answer to be incorrect then by all means make an alternative selection, otherwise leave well alone, and click OK.

I think you will agree that the warning in figure 12 is a lot more user friendly than the one that appears under similar circumstances when Ask When Opening is unchecked. At least with this option you now have the opportunity to assign an alternative profile to the image before it opens.

(ii) Missing Profiles: Ask When Opening

Choosing this option means that Photoshop has been set to present the user with a warning when the image being opened has no embedded ICC profile. The warning looks similar to the following (figure 13) and again contains three options. The preset or default selection is dependent upon the Color Management Policy in operation at the time.


Figure 13

The above example is preset for how the dialog would appear when the Color Management Policy is set for Preserve Embedded Profile. Since no profile is embedded Photoshop will try to assign the Working Space profile to the image. No conversion takes place, just the assignment of the Working Space profile.

The lower Assign Profile (and the associated and then convert to working RGB) checkbox is the best choice if you know the source images' true color space and you want the image to appear correctly in Photoshop. Typically, this option will be used for images from a digital camera or similar device that does not embed a profile in the image file or provide accurate EXIF color space information.

(iii) Paste Profile Mismatches: Ask When Opening

Figure 14 below shows the Paste Profile Mismatch warning that appears in the event of the color spaces of the two images not matching.


Figure 14

Note that the terms preserve color appearance and color numbers relate to the source image, not the destination.

The various warning dialog boxes shown above are only a sample of those that may appear as you open or import images that contravene the defined Color Management Policy. However, I think that the text messages included in each should be more than ample to explain what each option does and will therefore allow you to make the appropriate choice.

Conversion Options

This section will only be present in the Color Settings dialog if the user chooses More Options. Figure 15 shows this section of the Color Settings dialog in its default configuration.


Figure 15

Engine: this is the name of the engine, which will be used for all color space conversions. Unless you have good reason to choose an alternative your should leave it at the default Adobe ACE setting. ACE is the direct equivalent of the Built-in engine used in Photoshop 5. Windows users should not be tempted to choose ICM. Mac users should keep in mind that the option chosen here will override the selection made in the ColorSync setup. Choosing the ColorSync engine is for Mac users as a bad a choice as Windows users choosing ICM.

Intent: this pop-up menu allows the user to select from four different rendering intents, namely Perceptual, Saturation, Relative Colorimetric and Absolute Colorimetric. Typically, most users will choose between either Relative Colorimetric or Perceptual. A short description on each is provided in the Description section of the Color Settings dialog. A more comprehensive explanation can be found in the Photoshop on-line help files.

With Relative Colorimetric it is only those source colors that are out of gamut (i.e. can't be viewed/printed accurately within the destination color space) that will be mapped to the closest in-gamut color, the remainder are left unchanged. This means that in the case of images with lots of out-of-gamut colors the visual relationship between the colors (after conversion) will almost certainly change. With Perceptual, all colors of the source color space will be mapped to the nearest in-gamut color of the destination color space thus maintaining the visual relationship between colors. In other words, with Perceptual the whole image color gamut will be compressed so that it fits within the new color space. The Photoshop default and my recommendation is Relative Colorimetric.

Use Black Point Compensation: this should be kept checked. Black Point Compensation ensures that the darkest neutrals of the source color space are mapped to the darkest neutrals of the destination color space. In most circumstances toggling BPC ON or OFF will result in no obvious change to the image appearance, but in some situations converted images will look horrific if BPC is Off, so be very careful with this setting.

Use Dither (8-bit/channel images): as with Black Point Compensation this should be kept checked. The description box at the bottom of the Color Settings dialog box will give you some clue as to what it does.

Advanced Controls

As with the conversion options, this section will only be present in the Color Settings dialog if the user chooses to activate the More Settings option. Figure 16 shows this section of the Color Settings dialog in its default configuration.


Figure 16

An explanation on what each of these options do is provided in the Description box and on-line helps files. The consensus appears to be that both settings should be left in the default Off condition.

The Desaturate Monitor Color option is the one that has greatest potential to cause confusion, as it will result in the image preview to become progressively less saturated as the percentage is increased. Those choosing to work in very wide color spaces may find it useful, however, the majority of Photoshop users should leave it Off.

Saving Out Your Own Default Color Settings

Select the Save button and give your settings a Name and Description by which you can call them back in the future, if for some reason you make a temporary change. Also note that you can have as many different sets of settings as you wish, although only one can be active at a time. Figure 17 shows my preferred color settings.


Figure 17 - Customised Color Settings Configuration

If you're using Adobe Creative Suite 2 you'll also want to make sure that all color handling within the other application matches with Photoshop. To help you with this task Adobe has provided a feature within Bridge (Edit menu > Creative Suite Color Settings) that enables you to synchronise the color settings for all of the suite applications. Remember, that this feature is only available when you have Creative Suite 2 installed.


Figure 18 - Synchronise Creative Suite Color Settings

Section 3 - Soft Proofing

A frequently asked Photoshop questions is: why don't my prints match the screen? Generally it's down to poor monitor calibration, but on other occasions it's simply the fact that the user has an unrealistically high expectation of what can be printed.

This section will discuss the options and commands associated with the Soft Proof feature. As you work your way through it you'll notice that I haven't included any reference to specific printer driver set-ups. This is because they have been covered in a separate tutorial Photoshop CS2 - Managing color when printing.

So, what's soft proofing?

Basically, soft proofing is nothing more than using your monitor to simulate a printing device. However, accurate soft proofing is dependent upon the quality and accuracy of the monitor profile and the media profiles for each printer/media/ink combination that you're attempting to proof.  Configuring Photoshop for soft proofing is done via the View > Proof Setup > Custom menu as shown below.


Figure 19

Proof Setup only affects the current or active document on your desktop. So, if you want to define your own default Proof Setup (a wise move) you must configure the proof setup via the Custom menu option with no documents open. Alternatively, if you do have a document open then hold down the Alt/Option key to activate the ->Default (i.e. Save proof profile) button in the Customise Proof Condition dialog.

The various proofing options are:

  • Working CMYK - soft proofs the document using the current CMYK working space defined in the Color Settings dialog.

  • Working Cyan, Magenta, Yellow and Black Plate or Working CMY Plates - soft proofs the document using the current CMYK working space defined in the Color Settings dialog.

  • Macintosh RGB and Windows RGB - soft proofs the document using the standard Mac or Windows monitor profile (i.e. Apple RGB and sRGB respectively).

  • Monitor RGB - soft proofs the document using your actual monitor profile. If the document looks bad when this option is selected you know that your monitor profile is broken and needs to be recreated as described in Part 1.

The screenshot below shows a typical view of the new Proof Setup (i.e. Customise Proof Condition) dialog in CS2. In this example, I'm showing the configuration required for simulating an Epson R2400 inkjet printer. From this dialog you can easily select, configure and save your own customised soft proofing setup for any number of different printer profiles.


Figure 20

You begin the process by choosing the Profile from the Device to Simulate pop-up menu. In the example shown above I have selected the Epson profile for Premium Glossy paper (i.e. SPR2400 PremiumGlossy). In your case it will be the profile for the media that you want to simulate on the monitor.

Preserve RGB/CMYK Numbers

This option will only be available when the document and profiles are in sync, i.e. both are RGB or both are CMYK. Selecting the Preserve RGB/CMYK Numbers checkbox will usually result in a quite awful looking display, so don't make the mistake of choosing that option. Basically we are simulating how the document will appear if it's not converted to the actual device profile.

One use of this option is to enable you to see how the document would print if the appropriate media profile is not selected in the Print with Preview dialog. Normally it's best the leave the checkbox unchecked.

Rendering Intent

Rendering Intent is the setting that appears to cause most confusion and it's generally worth trying both Relative Colorimetric and Perceptual. Typically Relative Colorimetric will be best but some highly saturated documents will benefit from choosing Perceptual.

Use Black Point Compensation

I described Use Black Point Compensation previously when discussing the conversion engines. Typically, it will be best to keep it checked.

Display Options (On Screen)

There are two options (or checkboxes) shown in this section of the Customise Proof Condition dialog. The first: Simulate Paper Color allows you to simulate, on the monitor, the shade/color of the paper white. The second: Simulate Black Ink will enable you to simulate, on your monitor, the dynamic range defined by the media profile (i.e. how dark black will appear on the media you're printing to). Note that selecting the Simulate Paper Color checkbox will cause the Simulate Black Ink to be selected and greyed out. Not all profiles will support both options.

The resulting soft proof display can be quite disconcerting at first. By this I mean that the overall tone of the image may tend to look compressed or slightly color shifted (e.g. white takes on a blue cast). This can often occurs when using printer profiles that were created from scanner based profiling applications. In such circumstances it's probably best to leave the Simulate Paper Color and Black Ink options unchecked.

To save the customised proof setup simply choose the Alt/Option+Save button and give the soft proof profile a name that clearly indicates the printer/media combination for which it was created. The name of a saved soft profile will be appended to the bottom of the list immediately below Monitor RGB (Figure 21 below).


Figure 21

Section 4 - Managing the Document Color Space

As with other aspects of the Photoshop CS2 color management system we find that color space conversion and profile-embedding has changed little from previous versions. OK, so I said little had changed, but now I break the news that some things have changed. The  Assign Profile and Convert to Profile commands are now  found under the Edit  menu, which isn't a dramatic change, but it does have the potential to leave those already familiar with Photoshop a little confused.

Assign Profile

So what does Assign Profile do and when do we use it?  Assign Profile allows you to assign any profile of your choosing to a document. The command is intended for only a few limited uses, typically with documents that have been imported into Photoshop using a Twain module or a scanner package that has no means of embedding an ICC profile.

Assuming that the color management policy is not set to Off then a document imported into Photoshop without an embedded profile will be assigned, previewed and subsequently saved using the current Photoshop Working Space profile. Obviously, this may not be the most appropriate color space in which to edit or even save the document, so assuming the you have the correct source profile you can assign it to the document after you open/import it.

Itís important to note that assigning a profile does not change the document (i.e. it will not change the RGB/CMYK numbers or pixel values). Assign Profile simply provides Photoshop with a description of the actual color space that you wish to edit and view the document in. In other words it changes the document appearance or meaning of the RGB/CMYK numbers.


Figure 22

  • The Don't Color Manage this Document: option is used to instruct Photoshop to remove an existing embedded profile (sometimes referred to as untagging).

  • The Working RGB: option tags the document with the current default working space profile as defined in Color Settings.

  • The Profile: popup option allows us to assign a profile other than the default Working Space profile. In the above example I chose to assign a customised profile for a Nikon scanner.

Other potential uses for Assign Profile include the removal of an embedded profile (i.e. don't color manage the document).

Convert to Profile

Convert to Profile is basically an enhanced version of the old Photoshop 5.0 Profile-to-Profile command, the main difference being that with Profile-to-Profile you were able to define the source color space. In Photoshop CS2 this cannot be done since the source profile for the image is predefined and locked. The only way that the source profile can be changed is via the Assign Profile command discussed above.


Figure 23

In the above screenshot I show a document with the Adobe RGB (1998) profile embedded (Source Space) being converted to sRGB (i.e. the Destination Space). Whenever we make this conversion it will be the profile for the destination space that is embedded within the document when saved. Convert to Profile changes the RGB/CMYK numbers (i.e. pixel values) in order that the document appearance is maintained. The Preview checkbox allows the user to compare the conversion with and without Black Point Compensation, Dithering, and any one of the four rendering Intents. The ability to preview the conversion is a real boon and shouldn't be ignored, so use it to your benefit.

Also notice that the screenshot shows the Intent set to Relative Colorimetric. This was the default Intent I chose when I configured the Color Settings dialog earlier. However, as with many Photoshop setting the Intent is "sticky", which means that if I was to change it to Perceptual then the next time I choose Convert to Profile the Intent will be set to Perceptual.

Section 5 - Print with Preview

Whilst printing from within Photoshop is discussed in separate tutorial it's still worth providing a brief overview to round off this essay on color management.

The screenshot shown below shows the color management options within the Print with Preview dialog box that enable you to define the source and destination (target) color spaces along with the rendering intent used to convert the document between the two.


Figure 24 - Print with Preview

If you've been using a previous version of Photoshop you'll immediately notice that we now have a more extensive and very different  list of options available. You'll also notice that Color Management is now the default view for this dialog. Anyway, to keep things simple I will focus on only those settings that fall within the Print and Options area in figure X above. I will also explain the meaning of each option and hopefully give you better idea why certain combinations will work and others don't: -


  • Document: denotes the ICC profile embedded within or assigned to the source document. The example shown in figure X shows ProPhoto RGB, but it could be any number of user specified alternatives (e.g. sRGB, Adobe RGB (1998), ColorMatch). If the document has already been converted  to a printer/media profile using the Convert to Profile command, then the printer profile color space will be reflected here.

  • Proof: this field will normally display as (Profile: N/A). Once it's activated via the radio-button it tells Photoshop to convert the document on-the-fly from the source documents color space to the ICC profile shown in brackets. You can only alter the destination profile from within the Proof Setup dialog (see: Photoshop View menu). Also, note that you'll only ever need to use this option if you are intending to make Hard Proofs or Match Prints (i.e. emulating another printer such as a press), therefore I don't intend to discuss this workflow further in this tutorial.


  • Color Handling  - this is the new pop-up menu  from which you choose the preferred method of managing color when printing from Photoshop CS2. By adopting this approach Adobe have separated the workflow aspects of  printing from the media choices. In theory, this should make life easier for the user, but only time will tell us whether it has. There are four different choices: Let Printer Determine Colors, Let Photoshop Determine Colors, Separations, and No Color Management. Each of these choices has its own associated preset configuration in the Print with Preview dialog thereby helping you avoid erroneous settings.

  • Printer Profile - as its name implies this is the pop-up menu form which you choose the ICC profile associated with the printer/media combination you'll be using. This pop-up will only be active when the Let Photoshop Determine Colors is selected in the Color Handling pop-up.

  • Rendering Intent and Black Point Compensation - again, depending upon your choice in Color Handling one or both of these settings may be greyed out.

  • Proof Setup Preset - by default this pop-up menu is greyed out and will only be activated when the Proof radio button is selected. As mentioned above this option is normally only used when simulating or proofing other output devices such as a Press.

  • Description - this is a useful addition to the Print with Preview dialog in so far as it provides short explanations for each of the settings and options. The description itself is triggered when you hover the mouse over the various buttons and pop-up menus (e.g. Color Handling, Rendering Intent, Black Point Compensation, etc).

Section 6 - Saving Documents

Save As

Again, whilst not necessarily part of the color management system the process of saving your documents does involve Save As dialog throws up a host of useful features. The Embed Profile checkbox is very important and will reflect your choice of Color Management Policy. You can switch it ON or OFF as you please although the latter option is a bad idea in most instances. Notice that the dialog even informs us which profile is being embedded.

The screenshot shown below is how the dialog appears on a Windows XP system; the Mac OSX version looks slightly different, but they are functionally identical.


Figure 25

The other save options present in the dialog are those associated with Layers, Alpha Channels, Annotations, etc. Again, you can choose to uncheck them and so save the image without the layers, etc. The Save As a Copy feature is engaged by default as soon as you uncheck Layers; this prevents you trashing a lot of hard work.

Hopefully the material presented in this essay has been helpful and improved your understanding of Adobe's approach to managing color in Photoshop CS2. As noted throughout the essay there is vast body of material to be found all over the internet.

September 2005

Whilst on the subject of things Color Management I think it's worth mentioning a book "Color Management for Photographers" by Andrew Rodney (aka as the Digital Dog). This book contains a wealth of useful information, tips, tricks and tutorials. Better still it's right up to date in that it covers all of the changes made in Photoshop CS2. I was privileged to have the opportunity to review the book prior to publication and would have no hesitation in recommending it to anyone interested in learning more about the practical issues of color management facing photographers. Copies can be obtained from Amazon



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