The most commonly reference target used for scanner profiling is the standard IT8.7 target which was first developed by Kodak . In actual fact, the color gamut of the scanning target is much smaller than the actual gamut that the scanner is capable of.
Gamut extrapolation
With the captured image of the color target, the profiling utility extents the color gamut to outside that of the reference target so that brighter and saturated colors will be contained in the gamut for the generated profile. Profiling programs that can better "predict" such behaviour yield higher accuracy in overall color reproduction.
By incorporating additional white points into the reference and captured data during profiling with PM5, color gamut, tone linearity and color matching, all were improved.
ΔE2000
average 90% 95% max
Profile
Monaco MP 1.69 2.21 2.31 2.70 (ver 4.8)
standard PM5 1.99 2.63 2.79 3.23 (ver 5.0.10)
Epson generic 2.15 3.39 3.93 5.77
PM5 with added
1 white point 1.62 2.10 2.57 3.43 see note1 -added WP #265
2 white points 1.21 1.78 2.26 3.08 see note1 -added WP #265 & #266
note1: white points were added
Data was extracted by scanning the dtp41 calibration strip, where Lab was the measured value of the white reference with a spectrometer, RGB was the device RGB value of the same white point extracted from the no-color-managed scanning data.
b) Patch ID#265
Similarly, this was the white point from the x-rite color-checker SG target where Lab value was taken from the reference set and RGB was extracted from the scanned image.
Comparing the Linearity of the 3 primaries
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