Archived posting to the Leica Users Group, 2002/03/26
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On 3/26/02 3:38 PM, "Austin Franklin" <darkroom@ix.netcom.com> wrote:
>> If you don't agree with this consider the fact that *all* images output to
>> consumer printers are reduced to 8 bits before being printed.
>
> GRAYSCALE images, yes...but color images are 8 bits/color...and there are
> three colors per pixel, so color is actually 24 bits/pixel...which is why
> you can manipulate color images in an "8 bit space" without getting into any
> trouble...and grayscale in 8 bits is far more "sensitive".
Correct, but we are used to talking about '8 bit color images' I think.
Your point about the flexibility with color image manipulation is a good
one, but you occasionally run into images which confound you. For example,
take an image where most of the detail is in one or two colors, such as this
one:
http://www.pinkheadedbug.com/paw/pages/week8alt2.html
Because the red and green tones are so dominant, and relatively uniform in
tone, this image can become posterized very easily with manipulation. For
example, converting it to grayscale reveals very ashy tonalities in the
green highlights. When you look at the green channel in the histogram, it's
a disaster area. In this case, either converting to 16-bit before
manipulating, or using a 12-bit scan (which I didn't do) would reap real
benefits.
- --
John Brownlow
http://www.pinkheadedbug.com
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