2020.02.13 22:23 "[Tiff] Tiff Thumbnail questions", by acorn12

2020.02.14 00:24 "Re: [Tiff] Tiff Thumbnail questions", by Olivier Paquet


I have removed a few duplicate questions and tried to provide some answers.

I have looked at the thumbnail utility I found as part of gnuwin32, presumably associated with libtiff, but it seems that, while it does create a thumbnail image, and apparently attaches it to the existing file - my assumption from the description and the resulting file size - tiffinfo & tiffdump don't seem to give me any information about two images - or I just don't know how to interpret the data

SubIFD (330) LONG (4) 1<71663894>

The above line is an indication of more images (IFD = Image File Directory). Unfortunately, it looks like neither tool lists the contents of SubIFDs. SubIFDs were not part of the original TIFF spec so it is possible the tools predate them and nobody ever thought to update them with better support.

The questions I have not found answers to - after googling for the best part of a couple of days:

There are but most likely none of them are relevant here.

Not that I know. Perhaps others can be of more help here. But I think tiffinfo and tiffdump should be fixed too.

More questions:

That is decided by the thumbnail generating software which wrote the file. I would have expected the inverse as well, so that software which does not support SubIFDs would read the main image.

tiffinfo and tiffdump are low level utilities which only list tags. They don't do much validation about whether the image is correctly structured.