Subject | Re: Is RGB to Lab lossy? - was(Re: Lenses and sharpening) |
From | Eric Stevens |
Date | 10/06/2014 23:27 (10/07/2014 10:27) |
Message-ID | <f8063at26v6f058q2k4eb6riov4mkisimv@4ax.com> |
Client | |
Newsgroups | rec.photo.digital |
Follows | Alan Browne |
Followups | Alan Browne (15m) > Eric Stevens Martin Brown (10h & 17m) > Eric Stevens nospam (23h & 59m) |
Alan BrowneBut hang on: we do accept a certain degree of quality loss as part of the normal process of editing. It doesn't take much manipulation to turn a smooth histogram into something like http://pe-images.s3.amazonaws.com/basics/adjustment-layers/fix-white.gif Push things a bit harder and you can get http://www.snoopy.me.uk/misc/365project/histogram/comb3.jpg or even https://aperture64.files.wordpress.com/2014/09/combing.gif
On 2014.10.05, 20:55 , PeterN wrote:PeterNAlan Browne
On 10/5/2014 6:57 PM, Alan Browne wrote:Alan BrownePeterN
On 2014.10.05, 14:42 , PeterN wrote:We went through all this some many months ago. I demonstrated clearly that the amount of 'loss' was negligible in practical terms.PeterNAlan Browne
I would use the terem "color change." anstead of loss.
Any change is a quality loss. Whether that is colour difference, tone, brightness, sharpness ... whatever, it's a loss.
Then you are using a different definition of quality.
Not at all. A non lossy process would have:
RGB-A -->X-format -->RGB-B
with RGB-A identical to RGB-B
But - the fact is that with Lab
RGB-A -->Lab -->RGB-B
RGB-A =/= RGB-B, therefore there was quality loss.