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Tuesday, January 4, 2011

Color Printing Technique

The leap from computer monitor to printed output is where most professionals experience issues of color shift and a loss of punch in a photograph. Los Angeles-based pro Lee Varis takes us through the steps to get perfect prints.

This Article Features Photo Zoom

What Is A Color Profile?

Figure A
Understanding what a profile is will help you fully comprehend what happens in color-managed transformations. An ICC profile is a standard way of numerically defining the way a particular device (a scanner, camera, printer or monitor) renders color for a human observer under average daylight conditions. Color management involves linking these various device profiles together in a way that allows us to control the appearance of colors from one device to another. In order for this to work, a profile must reference the observable colors from a device to a device-independent model, a sort of absolute definition of color. Profiles are static definitions, and the dynamic calculations that move an image file through various profiles to arrive at the final output are handled by a color management module (CMM) that’s the mathematical engine for all the transforms.

Therefore, a profile is a special number transformer, a kind of black box called a lookup table (LUT), or more often a color lookup table (CLUT), which takes a set of numbers and returns another set of numbers. The first set of numbers can be from any kind of color device (RGB, CMYK or grayscale); the second set of numbers is the LAB definition of the color represented by the first set (Figure A). A profile “looks up” the LAB value for a color in a specific color space.

Figure B
You can think of LAB numbers as being independent of any particular device but representative of colors observable under D50 graphics industry-standard lighting. Therefore, a profile gives us a real color definition of the numbers from a digital file—in D50 light.

Some profiles are relatively simple rules based on a matrix with a few points defining a larger set of colors. Other profiles are larger plots of all possible colors in a particular set. Matrix profiles are commonly used for Photoshop’s working spaces and monitor profiles. Printer profiles are most commonly larger CLUTs, sometimes referred to as table-based profiles. The math surrounding all this is staggering. For the artist, a profile is merely a definition of the color rendered by a device translated into LAB. When photographers need to transform one set of device numbers into numbers for another device, they use profiles to “look up” the LAB colors and generate new numbers for the next device based on those colors (Figure B). LAB Color is the link between the two device numbers.

When the profiles for the devices you’re using are installed, you simply have to select the appropriate profile at the right time to manage the necessary color transforms.

Canon PIXMA Pro9500 Mark II

Canon PIXMA Pro9500 Mark II
The rubber meets the road in the final print. This is where all of your work and attention to detail in creating a perfect file with ideal color pays off. The print is, simply, the ultimate expression of a photograph. As a professional, you constantly need to be making high-quality prints, and more often than not, you need to make them fast to send them out to clients and prospective clients. The Canon PIXMA Pro9500 Mark II is ideally suited to the high-pressure studio environment. Capable of printing up to 13x19, the printer uses a 10-color LUCIA pigment-based ink set and has a maximum printer resolution of 4800x1200 dpi. Because speed is always of the essence these days, the PIXMA Pro9500 Mark II is also designed to keep up. Borderless 8x10 color prints come out in four minutes and five seconds, and 11x14 prints on 13x19-inch paper come out in seven minutes and 55 seconds. Estimated Street Price: $849. For more information, contact: Canon, www.usa.canon.com.


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