1996.12.17 18:44 "Changing ORIENTATION of a TIFF", by Michael J. Callahan

1996.12.17 18:44 "Changing ORIENTATION of a TIFF", by Michael J. Callahan

I have learned about and solved all my other problems with some TIFF image file work I have been doing, thanks to the people who have helped me from here.

The problem I have now concerns the fact that the TIFF images I am working with are saved such that their orientation value is 3. So the users are unhappy that the images come up in thier viewers with the right side on the left (reversed). The fact that they can flip them to read correctly in their viewers is not an appropriate solution for them/us.

I have learned a lot about TIFFs in the last 2 weeks, but I am unclear on the specifics of the orientation value. I have read the specs on 4.0, 5.0. It seems to say that an image with orientation of 3 was saved with the top left hand corner at the bottom right side. Why is that done? Should a viewer recognize this orientation value and perform rotation needed before displaying the image so that top is top and right is right? XV doesn't, Tiffview doesn't, none I've tried do. Besides, I will not be able to dictate the viewer used by our users, so that is not the answer anyway.

It seems I most likely need to be able to read the existing image file, convert the TIFF data such that it's orientation will be an un-reversed value of 1, and then write a new TIFF file as a result.

Can LibTiff be used for this? Has anyone done this? Do you have any insight as to how to accomplish this with that library? I have preliminarily looked at some documentation on it and it was not immeadiately clear to me how to begin, perhaps with more study.

I am trying to track down where the images are originating and will see if the scanner cannot scan them and save them in orientation 1, but I am not hopeful so far...

Thanks in advance...