2000.06.10 13:15 "Add: Resized version", by Ivo Penzar
I recently ran across an MRI (Multi Resolution Image) TIFF file, created by "optirastoras: 1.6.0, 2" from "Optigraphics Corporation".
Observe that resized versions are missing PhotometricInterpretation and both TileWidth and TileLength tags. As the detailed analysis shows, they share these attributes from the IFD 0, so the "optirastoras 1.6.0, 2" probably thought it would not be necessary to repeat them for IFDs 1 to 5.
In fact, Compression tag is also missing for IFDs 1 to 5. libtiff concluded uncompressed data (default), but "optirastoras" meant Fax4 - as specified for the full size bitmap stored in IFD 0. That was actually the cause for TIFFReadTile() to fail with IFD 5 (should have debugged it).
Anyway, I am still asking for your opinions about "industry standard" usage and support for multiresolution TIFF images. E.g., which standard apps would create them, do they allow for user to specify what resized bitmaps to create, of which photometric type, etc. Also, do you know of multiple page TIFF files containing resized versions for some/all of its pages. I.e., some IFD tags would have bit 0 raised up, some bit 1 raised up, and some both (?!) - not to mention their possible masks: NewSubfileType bit 2 raised up. I am still not sure would that be compliant with TIFF rev. 5 (6), not to mention which standard apps would support them. Specially I am not quite sure which standard TIFF readers actually use those resize bitmaps to speed up stretching and so. And for TIFF editors: would they then really update both the original image and its resized version(s)?!