Mr. Fancy-pants,
I’m new here and relatively new to the concept of color channels and using them to adjust overall color in an image. I’m afraid that I just don’t get this. I’ve read the article from earlier in this thread and I’ve Googled and read several other articles that attempt to explain color channels but none of them make any sense to me. The article referenced above immediately clicks the monochrome check box once it gets to the channel mixer so it neglects to answer my questions.
I get that there are different color models and color spaces and that an image can be broken down into red, green, and blue elements. What I don’t get is how the “red channel” can have a green and blue element or value or level. Every explanation I’ve found about color channels starts by explaining color models and then goes on to break down an image into three colors. When they explain RGB they show that pixels are made up of three colors and changing the intensity of any one of those three colors in a pixel results in a different shade. I get that. It makes sense. But then when they talk about color channels they all explain it as if the red color channel is only the red value of each pixel. So if there is no red in a certain pixel than the red channel would be black. If the red channel is only the red value in a pixel, then how can you adjust the green or blue in the red value? And, why would adjusting the blue value of the red channel cause blues to turn purple. I realize that it does work, I just don’t get why and nobody seems to be able to explain it. All that anyone can do is use examples to show that, for example, blue turns to purple when you increase the blue in the red channel. I guess if I experimented with this long enough I could just train myself to know what effect changing these levels will have, but that still won’t help me to understand why they have the effect they do.
What is a channel? Clearly it’s not what I think it is. There is some major abstraction taking place here and none of what I’ve read seems to explain it. I apologize if I’m being really hard headed about this but I really want to understand it. I think what would be helpful would be for it to be explained on a pixel by pixel basis. For example, if I have a pixel with an RGB value of R50-G200-B10 and I change the blue level of the red channel, what will I end up with? It’s been pointed out that just adjusting RGB levels can’t achieve the same results as using the channel mixer but after you’ve made adjustments using the channel mixer, your pixels will still have an RGB value and I assume it will be different in some way from the original. I imagine that the algorithms used to make those adjustments are very complex but in the end, isn’t that all that is really happening? Are the channel mixer adjustments not just changing the RGB values in individual pixels?
I guess it’s really just the abstraction that’s confusing me. How can adding blue to the red channel make blue colors look more red? That’s counter-intuitive.