Color separation and color conversion Spectrophotometric and Lab value
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The value we touched in the printing environment is the value of CMYK. In the general public, the value combination of each CMYK must represent an actual color. Therefore, many customers believe that the printing house should not modify the files they come from. But in fact, why can the same set of CMYK values be printed in different colors?
For example, if a customer handed in a set of four-color film, he said that he would print 20,000 copies, but there is no printed or drafted paper for reference. Would you take the risk to print 20,000 copies without using the color draft? Under normal circumstances, we will first make a draft to confirm the color of the customer. Because the customer only has four black and white films, the color is not visible at all, and printing on different papers or different solid density and dot gain will directly affect the color change.
In fact, the above situation is equivalent to today's customer handed over the disc, there is no color sample, the file is CMYK value, and there is no actual color information. When opening these files, you must specify an appropriate ICC Profile as the color display.
Remember the last three questions about the three "C" and Lab values of ICC color management? Why do you want to use the Lab value as the color space for the intermediate conversion, because the commonly used CMYK value for printing is the device-dependent color, which means a set of CMYK values, with different outputs, such as different papers. Ink will have different color effects.
In order to make it easier for everyone to understand the ins and outs of color, start with the basics of color. In terms of color science, the most accurate description of the color is the spectral curve. Scientist Newton discovered that the sun's light will be red, orange, yellow, green, blue, blue and purple, so the color we see is from "Light".
We will refract the light reflected from the object and then measure the light of different wavelengths to obtain the spectral reading. The reading will be connected to obtain the spectral curve.