Profiling and Gamut Ranges
In this section I will measure the error in the scanner’s interpretation of the colors of the original IT8.7/2 color target with the help of a color management system. In other words, I will learn the coefficient of the color distortion introduced by the scanner into the image. Below are the gamut range diagrams for opaque (reflective) and transparent (emissive) originals.
The triangle-outlined gamut range is a projection on the plane and shows the scanner’s palette in the visible light spectrum. Knowing the coordinates of the vertexes of the triangles, it is possible to calculate their areas for comparison.
For the comparison’s sake, there are the gamut ranges of the standard sRGB and Wide Gamut RGB color spaces in the diagram (the former is used for the majority of monitors and the latter is the maximum area in the CIE La*b* space).
The next diagram is constructed by calculating the difference between the colors of the color target and of its scan. Note that Color Difference values above 5.0 are discernable by most people, i.e. evident for the “average” human eye.
The diagram suggests that the Perfection 3490 represents the colors more realistically – they are closer to the original colors of the color target. This is an advantage of the tested scanner, of course.