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October 2000
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2000.10.05 00:20 "Old-style JPEG and HP 9100C Digital Sender", by Tim Bell
Hi,
We've got an HP 9100C Digital Sender (network connected scanner) and
it seems to be producing Old-style JPEG TIFFs, which libtiff says it
can't read. (We're using Linux for this.) I thought I'd check here
before I sent a detailed bug report to HP tech support.
Running tiffinfo on one of the files gives:
qcf6.tif: Warning, unknown field with tag 512 (0x200) ignored.
qcf6.tif: Warning, unknown field with tag 513 (0x201) ignored.
qcf6.tif: Warning, unknown field with tag 514 (0x202) ignored.
qcf6.tif: Warning, unknown field with tag 519 (0x207) ignored.
qcf6.tif: Warning, unknown field with tag 520 (0x208) ignored.
qcf6.tif: Warning, unknown field with tag 521 (0x209) ignored.
TIFF Directory at offset 0x17898
Subfile Type: (0 = 0x0)
Image Width: 1654 Image Length: 2339
Resolution: 200, 200 pixels/inch
Bits/Sample: 8
Compression Scheme: Old-style JPEG
Photometric Interpretation: YCbCr
FillOrder: msb-to-lsb
Orientation: row 0 top, col 0 lhs
Samples/Pixel: 3
Rows/Strip: 2339
Planar Configuration: single image plane
Page Number: 0-0
(From looking at the file, I realised that stripping off the first 8
bytes would give a JPEG, and that resulting file seems fine.)
Now, the HP tech support assure us that the 9100C produces "Compliant
TIFF6.0 files". As I understand it, this is strictly true, because the
DRAFT TIFF Technical Note #2 which redefines JPEG handling under TIFF is
not actually part of a TIFF standard yet. However, TN#2 does include
this: "TIFF writers are strongly discouraged from using the 6.0 JPEG
design", so we should be able to use this to tell HP that they've
implemented the wrong JPEG spec for TIFF.
The HP tech support people want to recreate our problem. I'm going to
point them in the direction of the libtiff web page and software. Are
there pre-compiled Windows binaries available? I don't know whether
they'd go to the trouble of compiling their own.
Am I on the right track with all this? I'd really like HP to fix their
product to use the revised JPEG encoding, and I figure giving them as
much accurate info as I can can only help.
Thanks.
Tim.
--
Tim Bell - bhat@trinity.unimelb.edu.au - System Administrator & Programmer
Trinity College, Royal Parade, Parkville, Victoria, 3052, Australia