The term 'saturation' describes the intensity of a color's hue, i.e. how dark the color is. Zero saturation shows a gray image while the highest saturation shows an intense and vividly colored image. To change saturation of an image,

select Image: Adjustments: Saturation from the Origin menu.

For more specific information on this function, see documentation provided for the X-Function imgSaturation in the Origin X-Function reference file. This can be accessed from the Command Window by typing

help imgsaturation