It happens all the time. You tweak the image on your monitor until its colors are perfect. But when you print, perfect becomes puzzling as colors shift and your royal blue turns a common navy. An accurate soft proof -- a reliable on-screen preview of your printed output -- would have saved you from swearing.
With a good soft proof, you can more accurately manage color to optimize images for the print process, thereby avoiding surprises, saving paper, and ultimately making a much better print than you can achieve by trial and error. Soft-proofing isn't easy, but Adobe's $609 Photoshop 6.0 (800/833-6687, www.adobe.com ) can help you through the process. While other applications offer soft-proofing tools, none is as accurate and powerful as the latest edition of Photoshop.
You can apply the soft-proofing techniques in this article to any output process, but they're particularly useful for making color-accurate prints on desktop ink-jet printers. Unlike commercial presses, most desktop ink-jet printers produce colors that don't tend to vary over time.
Why Manage Color?
Many people think that the goal of color management is to make their prints look like the images on their monitors. But unless you live someplace where the laws of physics don't apply, that's not possible.
Monitors display many colors that ink on paper can't reproduce, whether the ink is applied by a desktop printer or a commercial press (see "Color Gamut Differences"). Monitors also show a wider dynamic range -- the range of brightness from black to white -- than printing can achieve. Since color management can't change the physical limitations of your printer to make it match your monitor, you need to make the image on your monitor match the limitations of your printer.
Every color in a Photoshop file is represented by a number. Color management changes those numbers as you send files from scanner to monitor to printer, so that the color you see remains as consistent as the physical limitations of each device allow. This is necessary because RGB and CMYK numbers represent shifting colors -- they produce different colors when you send them to different devices (they're often called device-dependent color models).
Color management can automatically convert images from your Photoshop color numbers to your printer color numbers, but automatic conversions won't handle every image optimally. When you squeeze a monitor's wide color gamut and dynamic range into a printer's smaller gamut and range, you have to sacrifice what isn't important in the image. You wouldn't make the same compromise for an image of a black cat in a coal cellar as you would for a polar bear in the snow -- but automatic conversions do. Great prints still take intelligent human intervention.
Step 1: Make a Profile
After you understand what color management can do for you, it's time to put it into action. The accuracy of the whole process depends on the accuracy of your monitor and printer profiles . Profiles describe a monitor's or printer's color space with numbers. Color management employs profiles to determine what colors the numbers represent and to calculate the new set of numbers you'll send to your printer to make it reproduce those colors.
Most of today's vendor-supplied profiles for desktop printers are accurate only if you use the printer vendor's inks and papers, because the printers, ink, and paper are consistent from unit to unit and batch to batch. But monitor profiles are another story. Manufacturing variance, lighting conditions, and user-adjustable brightness and contrast controls conspire to make every monitor unique, and no generic profile will describe your monitor's behavior accurately. If you want an accurate soft proof, you must make a custom profile for your monitor.
Software Calibration Software-only monitor calibrator systems, such as Apple's Default Calibrator (included in Mac OS) and Adobe Gamma (part of Photoshop), are better than nothing. Still, our eyes' ability to adapt to different lighting conditions, although normally a blessing, becomes a curse when we're trying to keep our monitors stable over time.
Hardware Calibration Instrument-based calibration tools, such as ColorVision's $399 OptiCal (800/554-8688, www.colorcal.com ), can keep your monitor in a more consistent state than a software-only visual calibration system ever will. Before you spring for an instrument-based monitor calibrator, though, check to see if your monitor has enough life left to make the investment worthwhile. Here's a simple test: In your normal viewing environment, turn the monitor's contrast all the way up. If the result isn't uncomfortably bright, your monitor is on its last legs and is a likely candidate for replacement.
For detailed information on how to calibrate your monitor, see www.bigpicture.net/main/features/systems-supplies/front_end/monitorcolor991212.html.
Step 2: Control Color Conversions
Color-managing an image for print should be your final step, so be sure you've made all your other tweaks before you start the soft-proofing process. Then duplicate the image; it can remind you of the way the image looked without soft-proofing, which helps guide your editing for the final print.
Now it's time to open Photoshop's Proof Setup dialog box (View: Proof Setup: Custom) to control color conversions. This is one option-packed dialog box (see "Forest for the Trees"), so a little explanation is in order.
Setup Menu The Setup menu lets you load saved setups. You can open multiple views of the same image (choose View: New View) and apply a different proof setup to each window. You can save setups for the papers you most commonly use and then apply them to different views, to decide whether an image will benefit more from the compressed tone and lesser saturation of a matte paper, or from the higher contrast and greater saturation of a glossy stock.
Profile Menu Choose the vendor-supplied profile for your printer and paper from the Profile menu. Output profiles are paper-specific, so make sure that you choose the correct one for the paper you're printing on.
Intent Menu This menu lets you choose the rendering intent Photoshop will use when converting from the working space to the print simulation. Rendering intents control the way Photoshop maps out-of-gamut colors in an image into the limited color space of an output device. It's best to use Perceptual rendering for images with strong saturated colors and Relative Colorimetric for images without. To see the effect of different rendering intents, select the Preview option and change the rendering intent, or open new views of the image and apply a different rendering intent to each one. Then pick the one closest to the result you want.
Preserve Color Numbers Option Selecting this option shows what will happen if you send the image to the output device with no color conversion. Mostly, it provides a dramatic illustration of why you need color management -- if you select it, your image will suddenly look very different, and almost certainly much worse.
Ink Black and Paper White Options By default, the Ink Black and Paper White options are both not selected; this creates a preview that maps paper white to monitor white and printer black to monitor black. The preview does not show either the paper color, which is usually grayer than the monitor's white, or the true printer black, which is often lighter than black on the monitor.
Select the Ink Black option to see the actual black you'll get on a print. You might not notice much difference if you're printing to a glossy paper, but with matte paper, checking the Ink Black check box shows you the slightly washed-out black you'll get on the printed page.
Select the Paper White option to see the effect of both the paper color and the dynamic-range compression that takes place going from the working space to print. (When you select Paper White, Photoshop dims the Ink Black check box.)
The most obvious effect you see when you select the Paper White option is the dynamic-range compression -- the highlights become darker because the paper isn't as bright as the monitor. Look away from the monitor while selecting Paper White. If you don't see the change taking place, it's easier for your eye to adapt to the new white point.
You can once again use different views of the image to look at the print simulation in different ways. With both the Paper White and Ink Black options not selected, you can gauge what's happening to the saturation. With only the Ink Black option selected, you're able to focus on shadow detail.
Save Proof Setup Once you've configured Proof Setup, you can click on the Save button in the Proof Setup dialog box to keep your proof setup for use on other images. If you save the setup in the Proofing folder (System Folder: Application Support: Adobe: Color: Proofing), it will appear on the Proof Setup submenu, and you won't need to revisit the dialog box.
Once you configure these settings properly, you're done with the Proof Setup dialog box, so you can click on OK to close it.
Step 3: Make Your Final Edits
Now you're working in an on-screen simulation of how your image will print. You can make final edits to optimize the image for the print process. Typically, you'll make small adjustments to saturation and to the highlight (and perhaps also the shadow) areas. If your paper white is very different from your working-space white, your soft proof will show the color shift that the paper causes, so you might also want to adjust the overall color balance.
A good way to accomplish these edits is to use the Adjustment Layers feature in conjunction with the new Layer Sets feature in Photoshop 6. Store all your optimizations in a layer set named after the print process that they're intended for, and you can easily turn them off when you want to print the image to a different type of paper or printer. Your master image will remain unchanged.
Step 4: Print the Image
Finally, it's time to print the image. I prefer to open the Print dialog box, choose Document as the Source Space, and set the Output Space and Intent to the profile and intent I used in Proof Setup. This ensures that the conversion that happens at print time is the one you've been simulating. Turn off all color management in the printer driver so you don't get a double correction that will result in a bad print.
The Last Word
Once you've learned the correspondence between the monitor image and the print, you'll be able to nail your prints the first time around, saving time, frustration, and money spent on ink and paper. That's the real goal of color management.
BRUCE FRASER is a coauthor of Real World Photoshop 6.0 (Peachpit Press, 2001).Color Gamut Differences: This image approximates the differences between color gamuts. The smallest figure represents a printer; the middle triangle demonstrates a monitor's wider gamut; and the largest triangle denotes the Lab color space, which comprises all colors in the RGB and CMYK gamuts.Make a Profile: Accurate monitor calibration is the first step toward accurate soft-proofing. You'll get the best results with a calibrator such as this one from ColorVision.Control Color Conversions: Compare the original image (left) with the color-managed version (right) to see the need for color correction. The printer shifts the image slightly toward blue and diminishes some saturation and contrast.Make Your Final Edits: Use a series of Curves and Hue/Saturation adjustment layers to shift the colors back from blue, increase the saturation, and restore as much of the lost contrast as the printer can reproduce.Forest for the Trees: Photoshop 6.0's Proof Setup dialog box has a bewildering number of options.