Colour channel
Refers to the Red, Green and Blue components from which colours are created.
Infrared cleaning works by collecting an infrared channel from the scan at the same time as the visible colour channels (red, green, and blue).
You can select each colour channel separately and adjust them until you get the correct overall colour you desire. Next you can 'saturate the image'. This makes the colours more vibrant - a bit like using Fuji Velvia instead of Kodak Ektachrome.
Artwork is scanned then separated in the CMYK colour channels onto 4 printing plates, printed in succession to create a full colour image.
Colour channels explained.
File formats Raw, Tiff, Jpg and Psd evaluated and explained.
Working with 16 bit files.
HDR to cope with high contrast images.
Interpolation explained.
Useful retouching tools.
Make the Densitometer your friend.
I copy and paste the colour channels into layers. Choose the preferred (new) layer as the "original" and hold it @ 100%. That's the base layer.
But you can also use it to tone your black and white photos by making adjustments within the individual colour channels.
This type of electronic IS works by combining an underexposed-then-boosted luminance channel with a colour channel that's probably somewhat blurred, so it's no surprise that it can give some slightly ropey results.
32-Bit colour
A digital image format that incorporates 256 shades in 8-bits for each of the three-colour channels (RGB) and includes a mask (alpha) channel with a possible 256 levels of opacity.
Search SWPP and BPPA ...
You can, however, simulate the effect of using traditional black and white film by desaturating colour channels independently in Photoshop or some other image editing program.
To modify contrast you can usually click anywhere on the line and pull it in any direction. You can usually also select one of the colour channels and modify contrast on just that channel which will affect the colour balance.
 See also: Digital, Channel, Image, Camera, Light
  
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