Find detailed descriptions of Photoshop functions?

I've been looking all over for an exact definition of how Layer/blending mode/difference works, that is, what does it do when applied to one or more layers? My manual doesn't say, it only says how to access it, nothing showed up on my web search, nor anything in the Adobe websites.

The actual operation I'm trying to do is compare two images and see the differences in color and luminance.

I'm using version 6 on a WinXP machine.

Thanks for any help and I'd appreciate a direct reply, if you don't mind.

Frank

kolwicz at minetfiber dot com

Frank,

You can copy the layer to a new layer, and view them in Difference Mode. BTW, direct replies defeat the purpose of a public forum.

Rob

Have you seen those links?
<http://www.arraich.com/ref/tool_blend_modes.htm>

Technical, but not always accurate when it comes to the math: < http://www.pegtop.net/delphi/articles/blendmodes/difference. htm>

Another good resource: < http://www.adobeevangelists.com/pdfs/photoshop/Blendmodemagi c.pdf>

Direct replies are Evil.