-----While input profiles help scanners “see colors accurately,” output profiles
make sure colors printed to one printer look the same as the same colors printed to a different printer.
-----Sounds like something that ought to happen automatically, doesn’t it?
Unfortunately, there are many different types of printers, and each prints color a little differently.
-----While most printing devices print CMYK (Cyan, Magenta, Yellow, and Black) inks, some want to be fed RGB (Red, Green, and Blue) information. Some printers use powder toners, others use liquid inks, others transfer dyes from ribbons, and some actually use melted Crayons - and they all print colors differently. There are actually even more variables in this problem, but you get the general idea…what sounds simple, simply ain’t simple! This is the basic reason why
printing the same picture to different machines delivers different results. Sad but true.
-----If you’ve ever viewed a number of types of televisions all displaying the same channel in a department store and noticed that of all the various displays very few pictures look the
same, you know the problem. Different manufacturers use unique electronic components, and each produces its own look.
-----High definition televisions look different than CRTs, plasmas, and rear projection televisions look different than LCD televisions. And so on. Different televisions use different technologies, and therefore look… different.
-----The television department manager’s job (lucky guy) is to make all these different televisions look as similar as possible Let’s call his job “Color Management.” How does he accomplish his feat? First he shows a common test pattern on every screen. This test “target” contains the full rainbow of colors from red to orange to yellow to green to blue to purple, and a truckload of different shades of gray.
-----He then starts tuning the color adjustments on each television, one at a time, trying to display the test target as faithfully as possible on each. He works on each one until he is convinced that he has tuned-in the best possible color settings for that television. If all the televisions are optimally tuned to the test target, each television’s picture display should look very similar to the others.
-----Although this is an extremely simplistic metaphor, the basic principle is accurate. If we are to produce the same color from different printing sources, we must “tune” the basic image uniquely for each device
-----While we visually adjust a television to accurately portray colors, we tune a printing device by an electronic color adjustment tool. The color adjustment tool is known as a profile.
-----As described earlier, a profile is simply an evaluation report… a color performance evaluation of a unique machine. A profile assesses the capabilities of a single machine so that color pictures sent to that machine, consider those capabilities, and portray color images as accurately as possible.
-----In the case of output profiles, a test target (much more detailed version of the one used for the television) is printed from the printer. That printed test target is then carefully analyzed by very sensitive measurement devices called spectrophotometers to see how accurately the device produced the colors in the test.
-----From the measurements taken, color limitations are discovered (and recorded) about each device. Truth is… no machines print all colors perfectly. Special software then uses these limitations to create a characterization of that particular printer called a profile.
-----Each profile is like a rap sheet for a specific printer. A profile tells any color file sent to a printer exactly what the limitations of that printer are, and how to best compensate for its limitations, producing the most accurate, consistent results.
