Soft-Proofing an Image for Print
Thanks to the wonders of color management, the digital darkroom offers a key advantage over the traditional, analog darkroom: You can see what will happen in the print before you actually produce it.
The naïve view of color management is that it makes your prints match your monitor. If you’ve read this far, you’ve probably realized that this is an impossible goal—printers can’t print the range of color that a good monitor can display. Instead, color management tries to reproduce the image as faithfully as the limitations of the output process will allow. In other words, you can’t really make the print match your monitor, but you can use your monitor to tune the print for the specific printer you’re using. What makes this possible is the output profile, which describes the printer, ink, and paper.
But color management knows nothing about images, only about each image’s color space. No output profile, however good, does equal justice to all images. When you convert an image from a working space to the gamut and dynamic range of a composite printer, the profile treats all images identically, using the same gamut and dynamic range compression for all.
Fortunately, the soft-proofing features in Photoshop let you preview exactly how the profile will render your images, so that you can make the necessary corrections. If you want great rather than good, optimize images for different output processes, because each image requires its own compromises.
You can use layers, layer groups, or Smart Filters to optimize the same master image for printing to different printers, or to the same printer on different paper stocks. This technique uses three basic elements:
- A reference image. Duplicate the image with Edit > Proof Colors turned off to serve as a reference for the image appearance you’re trying to achieve.
- A soft-proof. Use the Proof Setup command to provide a soft-proof that shows how the output profile will render the image.
- A layer group. Group each set of optimizations for a specific output condition (printer, paper, ink) into a layer set, so that you can turn them on and off conveniently when you print to different devices.
Make a Reference Image. Choose Image > Duplicate to create a temporary copy of the image in another window. The duplicate will serve as a reference for the appearance you’re trying to achieve in the print.
You need to make a duplicate rather than simply open a new view, because you’ll be editing the master image to optimize it for the print, and the edits would show up in a new view. The duplicate isn’t affected by the edits you make to the master file, so it can serve as a reference—a reminder of what you want to achieve in the print.
Arrange Windows. Click the Arrange Documents button on the Application bar and then click the 2-up icon (see Figure 8-25). This arranges the reference and output documents side by side. If the Application bar is off, choose Window > Arrange > Tile.
Figure 8-25 Arranging the two images using 2-up view
Set Up the Soft-Proof. In the image you’ll be editing, choose View > Proof Setup > Custom (see Figure 8-26). Load the profile for your printer and check Simulate Paper Color.
Figure 8-26 Setting up a soft-proof
All of the soft-proof views (using the different combinations of Paper Color and Black Ink) tell us something useful, but checking Simulate Paper Color is, in theory, the most accurate because it uses Absolute Colorimetric to account for the paper color. That doesn’t change the Rendering Intent you specified above that; both still apply. For example, if you create a soft-proof for a particular paper profile using the Relative Colorimetric rendering intent, Photoshop performs the following two stages of processing:
- Figure out the printed colors. Photoshop takes the document and uses the selected Device to Simulate profile and the selected Relative Colorimetric rendering intent to calculate how the document’s colors must be adjusted for the output conditions represented by the selected profile.
- Figure out the monitor preview. Photoshop takes the print colors it just calculated, applies the Display Options (and the Absolute Colorimetric rendering used by Simulate Paper Color), and runs all of that through your monitor profile to calculate exactly how to represent the document’s print appearance on your monitor.
Together, those two stages form the soft proof, and you can tell how important it is that each profile in the chain is accurate. Upon switching to the soft-proof view, you’ll probably see the following:
- Simulate Paper Color makes the image appear much worse. A soft-proof typically shows washed-out shadows, compressed highlights, and an overall color shift caused by the difference between the white of your working space and the white of your paper. Don’t despair—Photoshop isn’t wrecking the image, it’s previewing the unavoidable dynamic range compression and gamut compression that occurs when printing.
- White appears dimmer. Photoshop can show you the gamut and dynamic range compression only within the confines of your monitor color space, and it can do so only by turning things down, so white in the image is always dimmer than your monitor’s white.
- Black may be slightly lighter than it will actually appear in the print, because in many monitor profiles, black has a Lightness value of 0 in Lab. But because most monitors actually have a Lightness of 3 or higher, we tend to call a Lightness value of 0 a black hole black point.
- Some profiles, particularly older ones, may not be built with soft-proofing in mind. They do a good job of converting the source to the output, but they don’t do nearly as good a job of round-tripping—converting the output back to a viewing profile. A good third-party profiling tool can create custom profiles that tend to round-trip very well, as do many vendor-supplied profiles for recent professional-quality desktop printers.
Problems with profiles aside, the soft-proofs offered by Photoshop are not, in our experience, any less accurate than those offered by traditional proofing systems. You simply need to acclimate to them.
Make Your Edits. Start by viewing the soft-proof and the reference image side by side. After you’ve edited the soft-proofed image to more closely resemble the reference image within the limitations of the soft-proof, fine-tune your edits while looking at the soft-proofed image in Full Screen view.
Figure 8-27 shows an example of an image that looked fine on the monitor, but a soft-proof indicated that we needed to bring the shadow detail up into a range where the printer could reproduce them. We can accurately show only the final results, because the printing process for this book can’t show you the full tonal range of the reference image. In this example, we applied Image > Adjustments > Shadows/Highlights as a Smart Filter (see Chapter 11) so that we could later turn it off, since the adjustment was made only for a specific printing process.
Figure 8-27 Using soft-proofing to make output-specific edits
Handling Multiple Versions. It’s common to make output-specific edits as adjustment layers whenever possible, to keep them separate from the full-range image. (In Figure 8-27, we applied Shadows/Highlights as a Smart Filter because it isn’t available as an adjustment layer.) If there are a number of adjustment layers, we put them in a layer group named for the print process it addresses. That way, we can easily optimize the master image for different print processes by turning the layer sets on and off without having to create a new file for each print condition. Using this technique, we can keep a single RGB master file with built-in optimizations for each print condition, and let Photoshop do the conversion from RGB working space to printer space at print time. It’s also valuable when preparing images for CMYK output, which often involves greater compromises. We may do a final fine-tuning on the converted CMYK image, but we make heavy use of soft-proofing to get the RGB image into the best possible state to withstand the CMYK conversion before we actually convert it. Figure 8-28 shows a Layers panel with layer groups optimized for two types of output.
Figure 8-28 Using soft-proofing to make output-specific edits
Once we’ve edited the soft-proofed image to match the reference image, we use Full Screen view to take a final look at the soft-proofed image prior to printing. (We prefer the gray background, with the menu bar hidden—the black background makes the shadows look too light.)
When You Print. It’s important to remember that the choices in the Customize Proof Condition dialog don’t actually change the image—they merely simulate how it will look if you print under those conditions. Use the same profile, Rendering Intent, and Black Point Compensation settings for both the soft-proof and the final print. For example, if you made your edits viewing a soft-proof using the Relative Colorimetric intent, be sure you also choose Relative Colorimetric in the Print dialog. Don’t duplicate all of the Customize Proof Condition settings in the Print dialog; the rest of the settings are for proofing only.
Also, make sure you’ve enabled any layers, layer groups, or Smart Filters that apply to the output you’ve currently targeted. If an image contains a layer group of corrections for your exhibition-quality inkjet printer and another layer group of corrections for eventual conversion to CMYK, when you print to the inkjet printer you must remember to turn on the inkjet corrections layer group and turn off the layer group with the CMYK corrections. For the rest of the details about printing, see “Printing from Photoshop” in Chapter 12, “Image Storage and Output.”