The header file ImfRgbaYca.h declares this function:
Imath::V3f computeYw (const Chromaticities &cr);
Given a set of chromaticities, it returns the vector
V3f (w_r, w_g, w_b). If you are interested in how the
values are computed, take a look at the function definition
in ImfRgbaYca.cpp and at the function RGBtoXYZ() in
ImfChromaticities.cpp.
By the way, ImfRgbaYca.h defines a set of functions will
perform a high-quality conversion from RGB to luminance/chroma
(with sub-sampled chroma) and back to RGB. See the comments in
the file for more information.
Florian
Hồ Châu wrote:
For luminance/chroma images, if have chromaticities and white point
coordinates, what algorithm should my program use for calculate w_r,
w_g, w_b for this equation?
Y = R × w_r + G × w_g + B × w_b
from EXR Technical Introduction document.
Châu
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