1994.06.03 23:57 "libtiff", by Cameron Kellough
I am an engineering student at Harvey Mudd College working on a project on accessing the pictures taken by Logitech Fotoman digital cameras. My ultimate goal is to be able to read the tiff files outputted by the cameras using XV on hp 9000 series workstations. XV uses libtiff and is sending me some cryptic error messages from it. The version of libtiff that I am using is 3.21 apparently with no patches.
Here are the 7 messages I am getting:
- Warning, invalid tiff directory: tags not sorted in ascending order.
- Unknown field with tag 33909 (0x8475) ignored.
- Unknown field with tag 33908 (0x8474) ignored.
- TiffReadBufferSetup: No space for data buffer at scanline -1.
>From reading the hex dump of the tiff, I know that there should be four strips in it which should account for the 4 copies of the last message. From reading the sourcecode to libtiff, I know that it can deal with the incorrectly sorted tiff directory. By talking with Kevin Mackey, a developer support engineer at Logitech, I found out that tags 33908 and 33909 contain information about whether the camera's internal flash was used and for how long. The only one I am completely baffled by is number 4.
One of the nuances in this is that logitech stores a preview image in the file after the real image. I experimentally tried setting the IFD Offset in bytes 4-7 to point to the preview image and I was able to read it although it is too small to do a lot of good. If this little preview image reads, I can't see why the big one would be structured so much differently that it does not.
Thank you for any information you might be able to provide.
Student Engineering Computer Systems Manager
Harvey Mudd College
P.S. I can mail or make available by ftp a sample of the file format.