What is saturation?

mercphoto

I'm asking this question mainly from a mathematical perspective, not from a visual perception perspective. I'm a very mathematical person and I found that I understood exposure, shadows and contrast much better once I understood the math behind the moves. So I'm wondering what exactly does saturation mean? If I tell ACR to go +15 on the saturation what does that do to the numbers? Can anyone give me a sample curve, for example, that shows increased or decreased saturation? Thanks. For that matter, is +15 considered a big or small move in saturation?

jfriend

A start

mercphoto wrote:

I'm asking this question mainly from a mathematical perspective, not from a visual perception perspective. I'm a very mathematical person and I found that I understood exposure, shadows and contrast much better once I understood the math behind the moves. So I'm wondering what exactly does saturation mean? If I tell ACR to go +15 on the saturation what does that do to the numbers? Can anyone give me a sample curve, for example, that shows increased or decreased saturation? Thanks. For that matter, is +15 considered a big or small move in saturation?

Here's one place to start reading: http://en.wikipedia.org/wiki/Saturation_%28color_theory%29. This includes a formula for saturation in the RGB color space. And, you may want to read about the HSV color model with more directly includes saturation.

Here's my simplistic explanation. Saturation is a measure of the difference between the various color channels. No difference between the color channels is zero saturation and is a gray color. A high difference between the channels is a vivid color.

If you have a pixel of a given R, G and B value, you can reduce the color saturation to zero, by calculating the luminosity of that RGB value and setting all three color components to that value. A pixel with the same R, G and B values will be some shade of gray (no color). That's how you reduce the saturation.

High difference between the color channels is high saturation. To increase the saturation, the color is intesified and moved even further away from gray by creating more difference between the color channels. Dominant colors are increased, less dominant colors are decreased, still attempting to preserve the luminosity, but intensifying dominant colors.

mercphoto

jfriend wrote:

High difference between the color channels is high saturation. To increase the saturation, the color is intesified and moved even further away from gray by creating more difference between the color channels. Dominant colors are increased, less dominant colors are decreased, still attempting to preserve the luminosity, but intensifying dominant colors.

That makes sense. Thanks!