Subject | Re: Any Minolta/Sony users using UFRaw and GIMP? |
From | PeterN |
Date | 04/21/2014 15:57 (04/21/2014 09:57) |
Message-ID | <lj38530269d@news1.newsguy.com> |
Client | |
Newsgroups | rec.photo.digital |
Follows | nospam |
nospamThen use a MacBeth color chart.
In article <jvOdnVF7m_WVFs_OnZ2dnUVZ_tadnZ2d@giganews.com>, Alan Browne <alan.browne@FreelunchVideotron.ca>wrote:nospamthe conversions are also not lossless, something which is trivial to prove. make the conversion and subtract from the original. if they're identical, the result will be zero, which it definitely is not, and on an image i randomly picked, it's noticeable without subtracting.Alan Browne
Post before and after shots and the subtraction.
the random image was one i shot a month ago at a dance performance and it's not for public consumption. one performer in the image was holding a guitar and that is where the visible change was. there was also some minor differences on her clothing.
the key is that anyone who claims converting to lab is lossless is mistaken.Alan Brownenospam
Name each process step from start to finish.
open image, duplicate (image/duplicate), convert to lab and back to rgb in the second image (image/mode) then subtract (image/calculations). look at the histogram to see the extent of the changes.