103. About Color Management
66 Print an Image
104 About Adobe Gamma
105 Ensure That What You See Is What You Get
What you see onscreen when you view an image is often very different from what you get when you print an image on paper. Not only do your monitor, printer, and even your scanner use different methods to render color images, each device works with its own separate range of possible colors (also called a gamut). What this means is that, when representing an image onscreen, your monitor might display a grayish red for an area of an image, which is not reproducible by your printer as an exact match. The printer, in such a case, simply substitutes a close match to the grayish red from similar colors in its gamut. So, when the image is printed, you get something that's close to what it looked like onscreen, but not exactly. The best way you can deal with this messy situation is to create an environment that simulates onscreen (as nearly as possible) what an image will look like when it's finally printed. To do that, you use color management.
Why Manage Colors?
One of the tasks of color management is to match the gamut of colors your monitor uses with the gamut of colors your printer is capable of reproducing so that, in the best of all worlds, what you see onscreen as a "pale shade of greenish-blue" approximates that shade when printed. If the color of your son's shirt is a bit off when you print a photo, you might not even notice, but if his skin tone carries a slight greenish cast, it'll stick out like a sore thumb and the whole image will look "off."
When what you see onscreen is not what you get when an image is printed, you need color management (in this example, the girl's skin tone, hair color, and even the color of the tractor is different). See the Color Gallery to compare these two images.
Microsoft Windows has the unenviable task of translating colors from one device to another using specific ICM (Image Color Management) profiles for the devices involvedcommonly called ICC color profiles. All devices that use color should have one of these profiles installed (your monitor, printer, and scanner). Typically, the profile is located on the manufacturer's disc, and you install it at the time you install the device driver and other software. With a profile installed, Windows shifts its color gamut to match the device's specifications, so that "rosy red" shows up as exactly that on your monitor, printer, and scanner.
In the absence of an ICC color profile for a device (if you haven't installed one for your printer, for example, or you simply couldn't find one on a disc or at the manufacturer's Web site), Windows uses its own color gamut instead. The video card then takes over the job of trying to represent colors on the screen with accuracybasically by overriding the Windows default gamut with the one in the monitor's ICC profile. Photoshop Elements takes this one step further by making minor adjustments to these colors with some help from a program called Adobe Gamma.
Digital Cameras, Printers, and EXIF Data
Photoshop Elements uses information from separate camera ICC color profiles, when they are available. But both the Editor and the Organizer typically rely on EXIF information embedded within each of the images being imported, about how the camera perceived color at the time it took the picture. It is this information, specifically, that describes the camera's gamut. This is why proper photographic practices, including white balancing, are so important: When white looks the way it should for your digital camera, a calibrated monitor will precisely re-create that shade of white so that you won't make color adjustments to photos that might not really need them. For most digital cameras, the gamut used is sRGB. If you turn color management on within the Editor, the gamut used by the digital camera (and included in an image's EXIF data) is then used to translate that same information to the screen. For images that don't have a gamut listed in their EXIF data, you can choose which gamut to use. Again, sRGB is the gamut typically used by most digital cameras, so it's a good choice for use in the Editor when opening an image.
The color gamut information attached to image files follows a standard adopted by all major camera manufacturers (and some scanner manufacturers) called Exchangeable Image File Format (EXIF). EXIF data helps Photoshop Elements (and other graphics editors) determine where the camera's interpretation of "pure" red, green, and blue (the optical primary colors) are located on a theoretical chart of all visible colors. Photoshop Elements can then compare these coordinates to where its own "pure" primary colors are located on the same theoretical chart. After the program knows how to adjust these three pure colors, it can mathematically determine how to adjust all the other colors so that it displays onscreen what your camera saw when the image was recorded. The EXIF data is in turn used by most photo printers when an image is printed, so again, you get a pretty good printout of what the camera saw when the photo was taken.
You can view the EXIF data attached to an image using the Editor or the Organizer.
Some printers do not interpret EXIF data. Instead, they rely on Windows to provide them with a standard set of colors to use when printing an image that has EXIF data. This set of colors, by the way, has been re-interpreted at least once by the imaging program (such as Photoshop Elements) that imported the image file from the camera. This system is pretty good, but printer manufacturer Epson decided to do it one better.
Recently, Epson has engineered a system for its inkjet and photo printers that gives the printer the EXIF data for an image directly, by way of a bypass driver. Epson calls its system Print Image Management (PIM), and it enables its printers to see with a high degree of accuracy (albeit through two translators) what a PIM-enabled digital camera saw when it recorded an image. This way, "black" in the digital image (which optically is comprised of no red, green, or blue whatsoever) translates into "black" on the printed page (which, for pigment, generally involves a mixture of black ink with equal parts of cyan, magenta, and yellow inks). Essentially, PIMand its successor, PIM IIensure that both the Epson printer and the PIM-enabled digital camera interpret color and present EXIF data in the same way. If you plan to use the PIM feature of your printer as it was intended, you should purchase or use a digital camera that explicitly supports PIM as welland thankfully, many do, but you do have to look.
When PIM is involved, the color management scheme changes. Software called the PIM plug-in bypasses Windows color management and the ICC color profile, presenting EXIF data from an image directly to Photoshop Elements. The status of the PIM coalition changes often; as a result, other printer brands (such as Canon) might also be PIM enabled. Consult your printer's documentation to learn whether it is PIM enabled.