AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

1997.05.20 10:40 "unknown field with tag 34377 (0x8649)", by Christoph Kukulies
1997.05.20 14:23 "Re: unknown field with tag 34377 (0x8649)", by Tom Lane
1997.05.20 18:59 "Re: unknown field with tag 34377 (0x8649)", by Helge Blischke
1997.05.21 10:09 "Re: unknown field with tag 34377 (0x8649)", by John Cupitt
1997.05.21 08:23 "Re: unknown field with tag 34377 (0x8649)", by Adrian Baldwin

1997.05.20 18:59 "Re: unknown field with tag 34377 (0x8649)", by Helge Blischke

I got a file coming from some Apple Mac scanner program and when I want to look at it using xv 3.10a I'm getting

unknown field with tag 34377 (0x8649)
and
unknown photometric: 5

tifftopnm gives the same error.

The tag 34377 is an Adobe reserved proprietary tag used by Adobe's Photoshop program to store information internal to the program (like information on paths and layers etc.); libtiff and many other programs give just a warning and ignore this tag and the associated data.

Photometric 5 means CMYK (see section 16 of the TIFF6 spec), which cannot be handled by xv (as far as I know).

Try to convert the image by photoshop (on Mac, PC or UNIX (e.g.Solaris). If you don't have access to any photoshop or equivalent program, you could hack a little libtiff based program to do the conversion. the simplest method is: R = 255 - C; G = 255 - M; B = 255 - Y; ignore K. Of course, the resulting RGB colors might not be axact; there are a couple of different algorithms used for this conversion in prepress systems; and I do not know how photoshop does this.

Hope this helps,
Helge

--
H.Blischke@srz-berlin.de
H.Blischke@srz-berlin.com
H.Blischke@acm.org