2005.06.06 13:25 "Re: [Tiff] tifflib read/write question", by Quart-EDV
I want to write a IPTC Tag into an existing tiff file. Do I need to load the image first and then write a new image, or is there a way to read/write a tiff like this: open tiff, change tag, close tiff (-> write/excange tag).
Yes, you can do it that way. But every time after tag update you will need to rewrite the whole directory, so the size of your TIFF file will be increased.
The tiffset utility from the libtiff package does exactly what you need, so you can take it as a sample code.
as I see it is only possible to change the offset of a tag and write the changed directory with tiffset utility. But if this tag is not in a tiff this way is not the right one.
It seems to be, that I have to get all informations of a tiff, change/embedd iptc-photoshop and write a new tiff. There is a good source code coming with tiff_3.7.1 named tiffcp what is doing what I need.
I extended this source by adding iptc-photoshop embedding. If someone is interested in this source-code please write me a mail.