Google| Subject | Re: Any Minolta/Sony users using UFRaw and GIMP? |
| From | Eric Stevens |
| Date | 04/19/2014 03:50 (04/19/2014 13:50) |
| Message-ID | <j0l3l9hp5d82kr0djjqinnghltbn07uo98@4ax.com> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | nospam |
| Followups | nospam (12h & 9m) > Eric Stevens |
On Fri, 18 Apr 2014 19:41:33 -0400, nospam <nospam@nospam.invalid> wrote:
nospamI won't repeat the first time I asked but the second time it came up, it went like this:
In article <6993l9tk1g43mg0ejt2v6jks1tgaoufaq9@4ax.com>, Eric Stevens <eric.stevens@sum.co.nz>wrote:nospamEric StevensEric Stevensnospam
Fraser, Murphy and Bunting (Color Management) regard Lab as the work horse of color management systems.
it is, but photoshop doesn't work the way you think it does.
Maybe so but you have yet to explain how you think it works and how working inLab mode requires twice as many conversions as working in RGB.
i quoted from andrew rodney's book which explained it.nospamEric StevensEric Stevensnospam
Wikipedia http://en.wikipedia.org/wiki/Lab_color_space says
"Because Lab space is much larger than the gamut of computer displays, printers, or even human vision, a bitmap image represented as Lab requires more data per pixel to obtain the same precision as an RGB or CMYK bitmap. In the 1990s, when computer hardware and software were limited to storing and manipulating mostly 8-bit/channel bitmaps, converting an RGB image to Lab and back was a very lossy operation. With 16-bit/channel support now common, the loss due to quantization is negligible."
But none of this explains why you think Lab requires extra color conversions.
yes it does.
As above: please explain why.
the answer to that was given in what i quoted.Eric Stevensnospam
This is the third or fourth time of asking. I'm not trying to argue. I'm trying to find out.
then read what was posted.
But doesn't the Adobe color engine work in Lab anyway?internally, but that's not the same as making a conversion of the image twice."
My questions are intended to learn why you think working in Lab mode requires making a conversion twice. Your quotation above doesn't address that question at all and certainly it doesn't explain why you think converting an image to Lab mode in PS needs twice as many conversions as leaving it in RGB. After all, PS processes the image in Lab mode. All the conversion to Lab mode actually does is give the user a set of controls which work more directly on the color engine. --
Regards,
Eric Stevens
04/05/2014-
