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A Computer Darkroom Essay

In mid December 2006 Adobe broke new ground with Photoshop in that they provided users with a free Pre-release version of CS3.  QE and Engineering still had a lot more tweaks and additions to make before everything was ship-shape and ready for serious use, but to all intents and purposes it was feature complete. In the meantime the Photoshop community got to use an array of  new "bells and whistles" features much earlier than they expected.

 

So, now the final version is beginning to hit our desktops and the more observant will probably have noticed some functionality that falls under the banner of color management has been tweaked a little further. Actually, most aspects of Photoshop color management should still "look" and "function" very similar to what they have done since version 6. All of this is good news if you're migrating from an earlier version. Nevertheless, the differences between CS3 and previous versions are still sufficient that some explanation might proof useful.

A Swedish language translation of this essay is available here

Section 1 - 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 printers. Unfortunately, with such a diverse range of device types, technologies, and gamut limitations, it's inevitable that they will each 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 the purpose of a Color Management System (CMS).

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 will accurately describe the unique color characteristics of  each 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. As I have already mentioned, when a color is device-dependent, the appearance of  pixels with identical values will very often differ because each device has its own unique way of translating the color "value" or "number" into visual color. The role of  ICC profiles is to ensure that discrepancies that result from the widely differing color characteristics of each device are known to the color management system. 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 they represent the source device. For obvious reasons we can never convert a document into the color space of our scanner or digital camera. Output profiles on the other hand are two-way meaning we can convert From or To them. For example, we can convert a document with an embedded monitor profile into a document that has a  color profile describing a printer, or vice versa.

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 wise 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 its generally accepted these profiles are rarely as accurate as users 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 will provide 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 significantly 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  independent of any specific device. 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 any color profile to be useful to the color management system, they must conform 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.

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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.

Document Specific Color

Just like its more recent predecessors Photoshop CS3 continues to use document specific color settings, Actually, the Working Space that's chosen in the Color Settings dialog has a direct bearing on only three types of document, viz.: -

  1. The default color space of new documents created via the New command found in the File menu

  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 CS3 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 2 - Monitor Calibration and Characterisation

Monitor calibration and characterisation (profiling) is probably the most important aspect of a color managed workflow; yet many users seem oblivious to issues poor monitor calibration, etc can have on their documents. 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 your monitor profile. This conversion does not alter the actual document in any way; just its appearance on the monitor.

Adobe stopped shipping Adobe Gamma with the Mac version of Photoshop a few versions back, but kept it for Windows mainly because there was no software only alternative. Since Apple Display Calibrator Assistant was still installed within System Preferences Mac users never really found the absence of Adobe Gamma to be a problem because. However, given that Windows Vista doesn't play well with certain utilities, it was inevitable that Adobe Gamma would eventually be dropped from the Windows version of Photoshop. So, it comes as no surprise that CS3 is the first ICC aware version of Photoshop not to include its own monitor calibration utility, which means that some Windows users will have to find an alternative to Adobe Gamma.

Obviously, software only monitor calibration applications use the human eye to determine tone and color differences between a series of white/grey/black/color patches. However, it  should go without saying that the eye isn't the most accurate method of measuring these differences. Therefore, my recommendation would be to use a hardware based system such as the Datacolor SpyderPro3, X-rite Photo ColorMunki or X-rite Photo i1 Display 2.

Tip for Mac OSX users: a tutorial describing the process of calibrating a display with the Apple Display Calibrator Assistant can be found here.

Check out the following links for more information on the Xrite Eye-One and ColorVision Spyder

Useful Information on location of  ICC/ColorSync Profiles

Photoshop CS3 is only compatible with Windows XP with Service Pack 2 or Windows Vista on the PC platform and OSX 10.4.8 or higher on the Mac platform. The upside of this is that the ICC and ColorSync profiles are more easily found.

Profile locations:- 

  • Windows XP and Vista - sub-folder named Windows\system32\spool\drivers\color

  • Mac OSX - ColorSync profiles are generally located in either the Library/ColorSync/Profiles or Users/~/Library/ColorSync/Profiles  folder

Section 3 - Photoshop CS3 Color Settings

The Color Settings dialog is the control room for the Photoshop color management system, and like all control rooms it can appear complicated. If you already  use Photoshop CS or CS2 you'll likely have Color Settings configured to meet your needs, and it's probably best that you stick with those settings. On the other hand new users should pour themselves a cup of strong coffee and pull up a chair because what follows is not always easy to understand, and may take a few attempts to sink in.

Whether you use Mac or Windows  the appearance and list of options within the Color Setting dialog, and elsewhere within Photoshop CS3, is to all intents and purposes identical. So, begin by opening the Color Settings, which is found towards the bottom of the Edit menu.

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Figure 1 - Photoshop CS3 Default Color Settings

The first thing that I will draw your attention to is 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.

The default RGB color 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 nor would it be strictly true. Therefore, I will work my way through each section of the Color Settings dialog in turn.

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.

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Figure 2

Working Spaces

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

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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 color 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 four other Working Spaces, these historically being the most popular choices of Photoshop professionals, but not necessarily the best. 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. Notice the inclusion of ProPhoto RGB, which was previously only available from the extended list of profiles. ProPhoto RGB has been my preferred working space for a few years now. It's actually a very wide color space that encompasses the entire range of colors that your likely to encounter. For this reason it's now generally regarded as the optimum color space when your output is destined for dye-sub, inkjet photo printers or Hi-fi color. However, be warned that opening or viewing documents that use this color space in non color savvy (non ICC compliant) applications can result in colors appearing significantly different from those shown in Photoshop.

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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 color space of your monitor as created by your calibration utility or hardware calibration device. 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 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 differs 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!

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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.

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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.

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Figure 7

Color Management Policies

Color Management Policies was a new and very important feature that was introduced by in Photoshop 6. Its importance continues in CS3, which is why I tend to spend so much time trying to explain the various options. Figure 8 below shows the new default setup, but this hides a lot of important information.

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Figure 8 - Photoshop CS3 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 the panacea for new users that some would have them believe. 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 and even within different applications on the same computer. 

  • 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 once you've completed editing same.

  • 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.

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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 CS3 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. If you're unclear as to why this should be then see explanation of document specific color in Section 1.

  • 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 and 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 some Photoshop dinosaurs 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 warning shown below (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.

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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 CS3 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.

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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.

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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.

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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.

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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.

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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 you 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.

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 documents containing 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 document color gamut will be compressed so that it fits within the new color space. The Photoshop default 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/print horrible 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.

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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.

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Figure 17 - Customised Color Settings Configuration

If you're using Adobe Creative Suite 3 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 3 installed and activated.

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Figure 18 - Synchronise Creative Suite Color Settings

Section 4 - 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 CS3 - Managing Color When Printing".

So, what is 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.

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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 need to 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). Both options assume that the simulated monitor will display your document without using color management.

  • Monitor RGB - soft proofs the document using your actual monitor profile. Again, this option assumes that the simulated monitor will display your document without using color management.

The screenshot below shows a typical view of the new Proof Setup (i.e. Customise Proof Condition) dialog in CS3. In this example, I'm showing the configuration required for simulating Premium Glossy Photo Paper on an Epson R2400 inkjet photo printer. From this dialog you can easily select, configure and save your own customised soft proofing setup for any number of different printer profiles.

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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). A comprehensive tutorial describing the technique of soft proofing can be found at the following link: here

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Figure 21

Section 5 - Managing the Document Color Space

As with other aspects of color management we find that color space conversion and profile-embedding hasn't changed in Photoshop CS3. I suppose you could say that since it wasn't broken in CS2 there was no need to fix it. Either way, for many Photoshop newbies it's difficult to appreciate the difference between  embedding a profile and converting to a profile..

Assign Profile

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

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.

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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 all subsequent versions of Photoshop, which includes CS3, 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.

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Figure 23

Figure 23 above shows 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 6 - Printing

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 new Print dialog box that enables you to define the source and destination (target) color spaces along with the rendering intent used to convert the document between the two.

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Figure 24 - Print dialog

Even if you've been using a version of Photoshop as recent as CS2 you'll immediately notice that the Print dialog has undergone a radical rework. We now have a more extensive and very different  list of options available.  You'll also notice that Color Management is still the default view for this dialog, but the preview window is now fully color managed with the ability to soft-proof images.  Anyway, to keep things simple I will focus on only those settings that fall within the Print and Options area in figure 24 above. I will also give a brief summary of each option and hopefully give you better idea which combinations are best suited to particular print tasks:

Print:

  • Document: denotes the ICC profile embedded within or assigned to the source document. The example shown in figure 24 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 elaborate on this workflow.

Options:

  • Color Handling  - this is the pop-up menu  from which you choose the preferred method of managing color when printing from Photoshop CS3. By adopting this approach Adobe have separated the workflow aspects of  printing from the media choices. It was first adopted in CS2, and the theory at the time was that it would be a lot more intuitive. However,  I'm not so sure that it actually achieved this. Anyway, there are still four different color handling options, but the names used by CS3 are slightly different  from CS2. Also note that each has its own associated preset configuration within the Print dialog thereby helping the user avoid erroneous settings.

  1. Printer Manage Colors - with this option Photoshop instructs the printer to carry out the conversion between the document color space and the printer vendors preferred color space. Photoshop will not change (convert) the document if this option is selected. This is the most appropriate option when you don't have ICC media profiles for your particular printer/media combination.

  2. Photoshop Manages Colors - with this option Photoshop will convert the document to the printer/media profile selected that you have selected in the Printer Profile pop-up. Many desktop printers are now supplied with generic media profiles, but much more accurate prints can be obtained if custom profiles are used. However, for this option to work correctly color management must be switched off in the printer driver.

  3. Separations - this option is used when printing CMYK images where each channel is handled separately. If your document is RGB the option will be greyed out.

  4. No Color Management - with one important difference, this option is similar to the Printer Manages Colors option described above. The difference being, that with this option, Photoshop will not instruct the printer to change to convert the document. This option is intended for special cases such as printing custom profile targets that require document color management to be turned off in both Photoshop and the printer driver.

  • Printer Profile - as its name implies this is the pop-up menu from which you choose the ICC profile associated with the printer/media combination you'll be using. This pop-up will only be active when Photoshop Manages Colors is selected in the Color Handling pop-up. By default, it will actually show the document color space, so make sure that you don't forget to choose the appropriate printer/media profile before hitting the Print button.

  • Rendering Intent and Black Point Compensation - again, depending upon your choice in Color Handling one or both of these settings may be greyed out. Irrespective of whether it's greyed out or not, most desktop photo printers (inkjets) will ignore these two settings when Printer Manages Colors is selected from the Color Handling pop-up.

  • Proof Setup - 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. The Simulate Paper Color and Simulate Black Ink work in the same way as they do in the Customize Proof Condition dialog described in Display Options, Section 4 above. However, it is important to note that they are tied to Proof printing, so don't expect them to be available when Document is selected.

  • Description - this is a useful addition to the Print 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).

The last item I want to mention is new and very welcome Match Print Colors checkbox that you'll find tucked away at the bottom of the Print dialog. With this checkbox activated the Preview display will show a screen rendered soft-proof of the document - the preview shown in Print dialog is now color managed (Whoopee!).

Section 7 - Saving Documents

Save As

Again, whilst saving your documents is not directly related to color management the 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, which was discussed earlier. The option to profile embedding ON or OFF can come in handy in a few situation. but  is generally not a good idea. Notice that the dialog even informs us which profile is being embedded.

The screenshot shown below (figure 25) is how the dialog appears on a Windows XP system; the Mac OSX version looks slightly different, but they are functionally identical.

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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 CS3. As noted throughout the essay there is vast body of material to be found all over the internet. A simple search using "google.com" and the key words Color Management is all that is required.

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. The book predates Photoshop CS3, but this shouldn't matter a lot since very little other than the Print workflow has changed since CS2. Copies can be obtained from Amazon

 

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