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December 2005
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2005.12.13 17:31 "Re: Writing EXIF data?", by Paul J Lucas
On Tue, 13 Dec 2005, Joris wrote: > > You do realize the 'blob' is an IFD, as I tried to explain? Yes. > Most people want to use LibTiff to read and write the tags in that IFD, too. I *could* do it that way, but, since I knew from the very beginning that doing such is currently impossible with libtiff, I asked about merely setting the entire EXIF metadata as a binary blob in a single shot. I've already constructed it. > But if you've done all that in another way, already, things may be easier, > and someone here may be able to point you in the right direction if a right > direction exists. That's what I've been hoping for since my initial post. > May I ask how you wrote that IFD that you refer to as 'blob'? I have other software that created it. > ... but apart from understanding there's little I can do. Then you had/have no reason to reply. > I recommend you explain how you wrote the 'blob' Why is that relevant? > and convince the right persons that all you want is to set the EXIF tag value > to a particular known offset. No, I don't want to set it to a particular known offset. If that's all I wanted, I wouldn't be posting here in the first place. As the TIFF is being created, data is being "streamed" to it. The libtiff library is keeping track of things like its current offset. This information is hidden from users of the library (as it should be). 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. - Paul