Name: GRXHLS Purpose: convert RGB color to HLS color Category: GRAPHICS File: pgplot.src Author: T.J. Pearson Use: see description below. Description: SUBROUTINE GRXHLS (R,G,B,H,L,S) GRPCKG: Convert a color specified in the RGB color model to one in the HLS model. This is a support routine: no graphics I/O occurs. The inverse transformation is accomplished with routine GRXRGB. Reference: SIGGRAPH Status Report of the Graphic Standards Planning Committee, Computer Graphics, Vol.13, No.3, Association for Computing Machinery, New York, NY, 1979. Arguments: R,G,B (real, input): red, green, blue color coordinates, each in the range 0.0 to 1.0. Input outside this range causes HLS = (0,1,0) [white] to be returned. H,L,S (real, output): hue (0 to 360), lightness (0 to 1.0), and saturation (0 to 1.0). Updates: Oct 16, 1998: JPT automatically extracted from source.