The UT is a great place.

Thank you Carlos, and all the ones who shared :)

In the end, the minimal code looks like:

FUNCTION sepia_tone

LPARAMETERS iColorId,iColorCount

DECLARE INTEGER ColorAdjustLuma IN shlwapi.DLL SHORT iRGB, SHORT iLuminance, SHORT iRelativeColor

RETURN GETCOLOR(ColorAdjustLuma(RGB(112,66,20),INT(iColorId*1000/iColorCount),0))

As long as dependancies do not get in the way, the shorter the better.... I'll take that at this stage:)