RE: Re Gamma, dithering and device calibration
RE: Re Gamma, dithering and device calibration
- Subject: RE: Re Gamma, dithering and device calibration
- From: "michael shaffer" <email@hidden>
- Date: Sun, 4 Aug 2002 15:49:20 -0230
Bruce J. writes ...
>
Resampling in Photoshop simply averages the pixel values. So a 0/255
>
checkerboard or striped image would properly average down to 128. This
>
calculation *does not* depend on the gamma of the image data.
>
>
The original writer (Mark Ward) was asking about matching the apparent
>
brightness on a monitor, which is entirely different. Unlike
>
resampling, the
>
answer to his question *does* depend on the image gamma.
Although I threw the post away, I believe he did ask (2nd part of his
query) why resampling is not with respect to gamma. That is ... it would
imply that if you were to resample 2 identical images, 'cept that one was in
Colormatch and the other in AdobeRGB, you'd end up with different colors
because both are simple numeric averages but are contextually in different
tonal spaces. That is, averaging the tones is different than averaging the
numeric values ... UNLESS you are in gamma=1.0 space (... hopefully not
raising a corollary to the "Timo" argument ...)
cheerios ... shAf :o)
Avalon Peninsula, Newfoundland
www.micro-investigations.com (in progress)
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