how do color channels get damaged?

[fatimzz]

Hey all,
Well, Im a newbie and I am sure there will be some eyes rolling when I ask this question :p But I have been wondering, when you guys talk about some xyz channel being damaged and workign around it to get a good result...how do some channels get damaged in the first place? Is it during scanning of a picture or even when the pic is taken by a digital camera? I tried googling it but I got things like how to color your hair :p Anyway, if someone can suggest a good/simple book on the subject, that would be very nice.
TIA
fatima

[Xaran]

It's not so much that a channel gets damaged as the damage shows more in a particular channel.

Christine

[Doug Nelson]

Channels aren't literally "damaged". What that means is that there is some fault in the image that is more noticable in one channel. Typically this will mean a color shift in an image caused by one channel (each channel being a color component) being weaker, noisier, or less accurate than the others.

[bart_hickman]

As the other's noted, it's really just a matter of isolating damage based on its color which is often distinct from most of the colors in the image itself.

However, I've seen damaged prints that you could say literally had damage to a channel because the photo was exposed to something (humidity, moisture, sun, age) and damage primarily occured to only one of the pigments in the print (perhaps because that pigment was less stable.) Since prints are done using primary colors, such damage tends to line up pretty well with color channels.

Do you want a book that describes how to fix these problems, or a book on the chemistry involved? You probably won't find a whole book on just that type of repair--maybe a small part of a chapter.

Bart

[fatimzz]

Thanks everyone for your replies.
Bart, your point about some particular pigment was the answer i was looking for.... i merely asked for the book reference in case ppl thought it was a stupid question and to go read it up