RGB
All of us know about RGB. RGB is a color space in which, colors are represented by Red, Green and Blue components. Each component can vary from 0-255 in value. See the RGB color space below. (Thanks to MSDN for the pic)

HLS
HLS is also a Color space similar to RGB. But instead of red, green and blue components, HLS contain Hue, Luminance & Saturation components. Its a color space in which the Hue, saturation and luminance of a color can be separated and modified. See the HLS color space below.( Thanks to Wiki for the pic. )

Well, how can you convert RGB color to HLS and vice versa? You can use the api’s – ColorRGBToHLS() and ColorHLSToRGB(). See the sample code snippet below.

#include "Shlwapi.h"
...
// Red color in RGB
COLORREF RgbColor = RGB( 255, 0, 0 );

// Convert to HLS Color space
WORD Hue = 0;
WORD Luminance = 0;
WORD Saturation = 100;
ColorRGBToHLS( RgbColor, &Hue, &Luminance, &Saturation );

// Its converted to Hue, Luminance and Saturation.
// You can adjust the parameters according to your wish.

// Now convert back to RGB.
RgbColor = ColorHLSToRGB( Hue, Luminance, Saturation );

You can generate a wide variety of effects by adjusting HLS parameters which cannot be done by using RGB. Designers always use these HLS components for generating creative images. Take Photoshop and have a try!

BTW, don’t forget to add Shlwapi.lib to project settings.

Targeted Audience – Intermediate.