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Figure A-4 Correcting Native Display Characteristics
It can be shown that the required transform (T) may be implemented as a pair of appropriately-sized
look-up tables (LUTs), on either side of a 3 x 3 matrix multiplication. The LUT preceding the matrix
multiplication (the “pre-LUT”) implements the desired standard transfer function or gamma response
curve, such that input values are correctly mapped per that standard into a “linear light” space. The
required matrix for the color remapping (which is referred to as R) is a combination of the matrix that
transforms R′G′B′ to X′Y′Z′ values under the target standard (A
S
), and the inverse of the corresponding
matrix for the existing display device (A
D
). In other words,
R = A
D
-1
A
S
This stage must then be followed by a second look-up table (the “post-LUT”), which linearizes the
existing display device; specifically, it contains the inverse of the display’s transfer functions γ
D(R,G,B)
.
The complete transform block (plus the LCD module) as implemented in the LP2480zx monitor is then:
Figure A-5 Color Space Conversion Hardware in the LP2480zx
36 Appendix A Advanced Color Management Features and Usage