Soft-Proofing Other Color Spaces
If you're sane, you probably want to get some sense of what your images are going to look like before you commit to a $50,000 print run. There are three ways to proof your pictures: traditional (print film negatives and create a laminated proof such as a Matchprint), on a color printer (such as one of the new breed of inkjet printers), or onscreen. Proofing images onscreen is called soft-proofing, and Photoshop offers soft-proofing capabilities limited only by the accuracy of the profiles involved.
One of the hardest and most important tasks in Photoshop is proofing your final output on your screen or on a color printer. Photoshop gives you very fine control over both. We discuss this in more detail in "Optimizing an Image for Print" in Chapter 8, "The Digital Darkroom," but here's the quick version:
- The Proof Setup command (View > Proof Setup) gives you full control over onscreen proofing simulations. You can simultaneously view the same file with different simulations in different windows.
- You can view how different rendering intents will convert an image to a destination space before actually making the conversion.
- You can see how an image prepared for one output process will behave when sent to another output process without adjustment: This is particularly useful when you're faced with the prospect of repurposing CMYK files made for one printing condition to work with another.
- You can work inside an accurate output simulation to optimize your image for a particular output process.
For this to work, you must calibrate and profile your monitor, and we highly recommend that you also take steps to control your viewing environment (see the sidebar "Creating a Consistent Viewing Environment," later in this chapter).
In Photoshop, soft-proofing has its own set of controls separate from the Color Settings dialog. These allow you to preview your output accurately, whether it's RGB or CMYK. This is a huge advantage for those who print to RGB devices such as film recorders or to photorealistic inkjet printers that pretend to be RGB devices. Soft-proofing is also a big improvement for those who print CMYK. We can soft-proof different conversions to CMYK while we're still working in RGB and have them accurately depicted onscreen. For example, you can quickly see how the same image would look on newsprint and in your glossy brochure.
The View > Proof Colors command lets you turn soft-proofing on and off. Soft-proofing changes only the onscreen display for the current document window, without altering other windows or saved image data. By default, Proof Colors works as follows:
- It first simulates the conversion from the document's space to working CMYK, using the rendering intent and black-point compensation settings specified in Color Settings.
- It renders that simulation to the monitor, using relative colorimetric rendering. If Use Black Point Compensation is turned on in Color Settings, it's also applied to the rendering from the proof space to the monitor.
The default Proof Setup settings probably don't represent the output you're trying to preview, so to really benefit from soft-proofing, you need to be more specific. Your first stop is the Proof Setup submenu (see Figure 4-14), which governs exactly what Proof Colors shows you. If your actual output conditions are represented by one of the menu items, choose it so that Proof Setup will use those conditions when it shows you the soft-proof.
Figure 4-14 The Proof Setup submenu lets you choose a wide variety of soft-proofing options, including your own custom settings.
However, chances are that the output conditions listed by default on the Proof Setup submenu aren't specific enough to represent your output conditions. To unleash the power of soft-proofing, you need to use the Customize Proof Condition dialog, which gives you the tools you need to nail your soft-proofs precisely and list them on the Proof Setup submenu.
Customize Proof Condition Dialog
The Customize Proof Condition dialog lets you independently control the rendering from the document's space to the proof space, and from the proof space to the screen. It allows you to preview accurately just about any conceivable kind of output for which you have a profile. You can open the Customize Proof Condition dialog (see Figure 4-15) by choosing View > Proof Setup > Custom.
Figure 4-15 You can control color conversions from the document space to the proofing space and from the proofing space to the monitor.
Custom Proof Condition. The Custom Proof Condition pop-up menu lets you recall setups that you've saved in the special Proofing folder. (On Mac OS X, this folder is in harddrive\Library\Application Support\Adobe\Color\Proofing. In Windows, it's in the Program Files\Common Files\Adobe\Color\Proofing folder.) You can save proof setups anywhere on your hard disk by clicking Save, and load them by clicking the Load button, but the setups you save in the Proofing folder appear on the list automatically. (Even better, they also appear at the bottom of the Proof Setup submenu, where you can choose them directly.)
Device to Simulate. The Device to Simulate pop-up menu lets you specify the proofing space you want to simulate. You can choose any profile, but if you choose an input profile (for a scanner or digital camera), the Preserve Numbers check box becomes checked and dimmed, and all the other controls become unavailable. Generally, you'll want to choose an RGB, CMYK, or grayscale output profile.
Preserve RGB/CMYK/Gray Numbers. The Preserve Numbers check box tells Photoshop to show you what your file would look like if you sent it to the output device without performing a color-space conversion. It's available only when the image is in the same color mode as the selected profile (such as when both are in RGB); when you turn it on, the Rendering Intent pop-up menu becomes unavailable, since no conversion is requested.
This feature is particularly useful when you have a CMYK file that was prepared for some other printing process. It shows you how the CMYK data will work on your output, which can help you decide whether you need to edit the image, convert it to a different CMYK space, or just send it as is. It's also useful for seeing just how crummy your image will look if you send it to your desktop inkjet printer without converting it to the proper profile (see "Converting Colors When You Print," later in this chapter).
Rendering Intent. The Rendering Intent pop-up menu lets you specify the rendering intent you want to use in the conversion from the document's space to the proof space. Since the correct intent depends on individual images, it's good to be able to test it. It defaults to the rendering intent specified in the Color Settings dialog. If you change it, it remembers your change. Saving a new proof condition also saves your selected rendering intent, so if you're continually being tripped up by the wrong intent, you can just save a proof setup with your preferred rendering intent and make sure to use it.
Black Point Compensation. When turned on, this option applies black-point compensation when converting from the document's space to the proof space. Keep this option turned on; the only exceptions are some obscure printing workflows that will tell you when it should be turned off.
Display Options (On Screen). The check boxes in the Display Options section—Simulate Paper Color and Simulate Black Ink—control the rendering of the image from the proofing space to the monitor. When both Simulate Paper Color and Simulate Black Ink are turned off, Photoshop does a relative colorimetric rendering (with black-point compensation if that option is turned on in Color Settings). This rendering maps paper white to monitor white and ink black to monitor black using the entire dynamic range of the monitor. If you're using a generic monitor profile, this is probably as good as you'll get (of course, with a canned monitor profile, you can't trust anything you see onscreen anyway). With a good monitor profile, though, you should check out the alternatives.
- When you turn on Simulate Black Ink, Photoshop turns off black-point compensation when rendering from the proofing space to the monitor, so the black you see on the monitor is the actual black you'll get on output (within limits). If you're printing to a low-dynamic-range process, such as newsprint or inkjet on uncoated paper, Simulate Black Ink will give you a much better idea of the actual blacks you'll get in print.
Turning on the Simulate Paper Color check box makes Photoshop do an absolute colorimetric rendering from the proof space to the display. (Simulate Black Ink becomes checked and dimmed, since black-point compensation is always disabled in absolute colorimetric conversions.) In theory at least, turning on Simulate Paper Color should give you the most accurate soft proof possible.
In practice, the most obvious effect of selecting Simulate Paper Color isn't that it simulates the color of the paper, but rather that you see the compressed dynamic range of print. If you look at the image while turning on Simulate Paper Color, the effect is dramatic—so much so that we look away from the monitor when we turn it on, then wait a few seconds before looking at the image to allow our eyes to adapt to the new white point. More importantly, we also make sure that we hide all white user interface elements, so that our eyes can adapt.
Obviously, the quality of the soft-proofing simulation depends on the accuracy of your monitor calibration and on the quality of your profiles. But we believe that the relationship between the image on the screen and the final printed output is, like all proofing relationships, one that you must learn. We've never seen a proofing system, short of an actual press proof, that really matches the final printed piece—laminated film proofs, for example, often show greater contrast than the press sheet, and may have a slight color cast too, but most people in the print industry have learned to discount the slight differences between proof and finished piece.
It's also worth bearing in mind the limitations of the color science on which the whole ICC color management effort is based. We still have a great deal to learn about color perception, and while the science we have works surprisingly well in many situations, it's only a model. The bottom line is that each of the different soft-proofing renderings to the monitor can tell you something about your printed images. We recommend that you experiment with the settings and learn what works for you and what doesn't.
Proof Setup Submenu
The Proof Setup submenu (under the View menu) contains several other useful commands. For instance, when you're viewing an RGB or grayscale image, you can view the individual CMYK plates (or the CMY progressive) you'd get if you converted to CMYK via the Image > Mode command. You can also use these commands to view the individual plates in CMYK files, but it's much faster and easier to either use the keyboard shortcuts to display individual channels or click on the eyeball icon in the Channels panel.
The next set of commands—Macintosh RGB, Windows RGB, and Monitor RGB—is available only for RGB, grayscale, and indexed color images, not for CMYK or Lab. They show you how your image would appear on a "typical" Mac monitor (as defined by the Apple RGB profile), on a "typical" Windows monitor (as defined by the sRGB profile), and on your personal monitor (as defined by your monitor profile) if you displayed it on these monitors with no color management. These commands might be useful when producing Web graphics, for instance. The rest of the menu lists custom proof setups saved in the Proofing folder.
The soft-proofing features let you see how your image will actually appear in the output, so you can optimize the image for the best possible rendition in the selected output space. They also help you see if the same master file can produce acceptable results in all the output conditions to which you plan on sending it, relying on color management to handle the various conversions. So whether you're a driven artist seeking perfection or a lowly production grunt doing the impossible on a daily basis, the soft-proofing tools in Photoshop will become an invaluable addition to your toolbox.