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April 2006
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2006.04.11 08:33 "Re: application supplied JPEGTables", by Joris Van Damme
Gerben, Gerben Vos wrote: > I agree that it would be nice to be able to specify the quantisation > tables using a pseudo tag. I've not had time yet to dive into tif_jpeg.c, but I will soon. Meanwhile, why are you refering to a pseudo tag? Would it not suit these needs, if the actual JpegTables tag can be set, and when next LibJpeg is used to compress, in this case, the application supplied tables that are set in this tag are used? > However, maybe for your application at this moment it would be easier > to do the JPEG compression yourself, and then use the raw strip/tile > writing functions? You can do that, because the tables inside the strip/tile are supposed to overwrite the tables inside the JpegTables tag, if there are tables in both. But a) are you sure LibTiff reads back like it is supposed to, in this case? b) that would be a (very small, perhaps negligable) waste of storage space. Or am I misunderstanding? Joris Van Damme info@awaresystems.be http://www.awaresystems.be/ Download your free TIFF tag viewer for windows here: http://www.awaresystems.be/imaging/tiff/astifftagviewer.html