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In the headers and documentation for ippiRGBToHLS (both for ipp v9 and v2017) the following pseudo-code is given
if R = M2 then H = Cb - Cg
if G = M2 then H = 2 + Cr - Cb
if B = M2 then H = 4 + Cg - Cr
referring to
David F.Rogers
Procedural Elements for Computer Graphics
1985.pp.(403-406)
However, in that book (2nd ed. 1998) on page 629 I read
if R = M1 then H = Cb - Cg
if G = M1 then H = 2 + Cr - Cb
if B = M1 then H = 4 + Cg - Cr
and this does give different results. I haven't checked what ipp actually does, but at least there is a discrepancy in the documentation and headers.
Regards,
Adriaan van Os
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Hi Adriaan:
It should be the mistake of document. I tested RGBToHLS function with simply code. The result is correct.
For instance, I tested with value of RGB is {56,45,36}, the output of MKL ippiRGBToHLS_8u_C3R function is like below:
And you could calculate the get value of H,L,S:
H=19/255*360=26.8 same as 60*(G - B)/(Max-Min)
L=46/255*100%=18
S=55/255*100%=21.6
Thank you for posting the mistake of developer guide document. We will fix it.
Best regards,
Fiona
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Hi Adriaan,
The problem has been fixed in document, please refer to have a check.
Best regards,
Fiona

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