Questions about separating RGB components

[engjoneer]

Richard, I discovered your website and your book as a result of a google search and immediately bought it from Amazon. I'm working my way through it and learning so much, not only about PE4 but also about color theory and RGB. Your book has begun to answer many questions I had about digital color. I appreciate your efforts.

I'm fooling around with RGB Color Components and have gone through the manual process as well as using the Power Tool. I have this question:

The layers named Red Component, Blue Component, and Green Component all employ the Screen blending mode. However, it seems that a blending mode does not actually change the pixels on a particular layer, it only changes the way that the pixels appear as they blend with the pixels on the layer underneath. Therefore, what is the "Green Component"? Is it the "Green Component" layer itself (Normal blend mode), or is it the "Green Compenent" layer with Screen blending merged with the "Red Component" layer underneath (also screened). Does this question make sense? Here's another way of asking: If I copy the Green Component layer to a new file it looks completely different since it's blending mode is "Normal" and there is no other layer for it to blend with. Does it still represent the "Green Component" of the original image??

Thanks!
Jon

[Richard_Lynch]

That's a pretty good question...and hopefully i can make sense in the breif answer here.

The components are representations of light in grayscale. If you copy the layer to another image and change to Normal, the representation is the same as a channel; the intensity of the component is stronger where the pixels are brighter.

Screen mode acts like light...it will only brighten a dark background. if the background is white, you will see nothing because there is nothing to brighten. My composite layers act like black screens to project light on with the component layers. all screened layers will merge for a result. I believe there is an RGB.psd file on the CD that helps you explore this. If you move the circles of light, the light combines and produces new colors...that is exactly what happens with visual light and color.

does that help?