sYCC (was Re: Digicam, sRGB and Photoshop)
sYCC (was Re: Digicam, sRGB and Photoshop)
- Subject: sYCC (was Re: Digicam, sRGB and Photoshop)
- From: Kevin Connery <email@hidden>
- Date: Tue, 26 Aug 2003 06:17:20 -0700
Jarkko Viljanen wrote:
>
What bothers is why Photoshop says it's sRGB if it's not?
That's a known feature/bug in PS and/or the EXIF spec; there's a flag in the EXIF data that denotes whether the file is
profiled, but no profile actually has to be present. The choice appears to be 'on' or 'off', with (an unstated?
unspecified? specified by the default?) assumption that if it's 'on' that it's sRGB. Adobe as a plug-in "Ignore EXIF
Color Space plug-in" to get around the case where a camera generates a profiled file that isn't sRGB. (See
http://www.adobe.com/support/downloads/detail.jsp?ftpID=1882 )
YCC is a color model more comparable to LAB or YUV than RGB or CMYK; it splits the information into a luminance section
(Y), and two chrominance channels (usually a Red-based and Blue-based ones as in Kodak's PhotoYCC, or the YCrCb used in
JPEG). In that light, it's only comparable to sRGB
Roger Breton wrote:
>
Isn't YCC the native encoding space for Kodak PhotoCD?
>
It looks like Kodak is trying to breathe life a product that has not met
>
with the expected market acceptance when offered as part of the PhotoCD
>
package for color pros. I presume the 's' stands for 'standard'?
YCC is a color model more comparable to LAB or CIEXY than RGB or CMYK; it splits the information into a luminance
section (Y), and two chrominance channels (usually delta-Red and delta-Blue-based ones as in Kodak's PhotoYCC, the YCrCb
used in JPEG, or the YCC used for TV). In that light, it's only comparable to sRGB in that the 's' supposedly stands for
'standard', and that they can both be described by a profile. sRGB, however, is a color space using the RGB color model,
while sYCC is a color space using a completely different color model. (Like SWOP vs sRGB -- both can be described with a
profile, but they're different color models, not just color spaces.)
Thoroughly confused yet?
The EXIF-Print consortium's companies DO have a number of info pages that say that digital cameras capture into the sYCC
space; that's not correct either, though it's possible that a low-level interpretation is taking place from the RGBG
bayer pattern to that before it gets saved as 'raw'. Of course, they also say that their printers can print in excess of
sRGB, which is the opposite of what those same companies say in other documents, where they tell you to use sRGB because
that's what the printer prints. :(
Don't you love standards? There are soooo many to choose from....
--kdc
--
"Learning is not compulsory. . . neither is survival."
Dr. W. Edwards Deming
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