2005.12.12 22:19 "[Tiff] Writing EXIF data?", by Paul J. Lucas

2005.12.13 21:08 "Re: [Tiff] Writing EXIF data?", by Andrey Kiselev


On Tue, Dec 13, 2005 at 09:31:52AM -0800, Paul J. Lucas wrote:

I want to "inject" the EXIF data and have libtiff set the correct offset to it in the EXIF_IFD tag. This is exactly the same as, say, setting the ICC profile via TIFFSetField: I already have the ICC profile data as a blob. How I created it is irrelevant.

These two are different cases. ICC tag is self defined, it always can be read, even if know nothing about profiles and how to work with them you can read and copy this tag and even dump it to user. But the thing which we usually call custom directory is not defined by its tag. ICC tag contains data offset, count and type, so we can read the whole chunk without knolege about its internal structure. EXIF tag contains offset to EXIF directory and nothing more. How can we read or write this chunk without parsing it? Ok, we can introduce a function to write it as a binary object, but how to read it afterwards? EXIF IFD may have any length.



Andrey V. Kiselev
ICQ# 26871517