2009.02.23 18:01 "Re: [Tiff] losslessly wrap jpeg file into TIFF", by Toby Thain

On 23-Feb-09, at 12:01 PM, Joris Van Damme ((AWare Systems)) wrote:

Toby,

• There's at least one JPEG colorspace that I know of that has no equivalent in TIFF, being YCCK. These files might not be too rare, I guess Photoshop likely uses this colorspace when saving CMYK imagery to JPEG.

>

> I'm sure Chris Cox will chime in here, but no colour space conversion > is applied by Photoshop when saving CMYKs. Such behaviour would be

> catastrophic to prepress workflows. I can't speak for details, but > the C,M,Y,K planes are stored independently in JPEG, as in TIFF or

> PSD - a de facto "separated CMYK" colour space similar to that > defined for TIFF.

> While I still think it likely YCCK in JPEG is/can-be/could-at-some- > time-be

produced saving CMYK imagery as JPEG in Photoshop,

That would not mesh with my 20 year experience with Photoshop, but I welcome a final word from Chris Cox.

--Toby

the exact origin is not the issue. The issue is, we have at least one JPEG colorspace that I know of that has no equivalent in TIFF, being YCCK. There's no doubt about that, I've several items in my JPEG testfile library to prove it, and a codec handling them that proves my understanding of these files.