2006.04.07 07:34 "[Tiff] LibTiff Suggestion, Need help to support application supplied JPEGTables.", by Kelvin Zhong

2006.04.11 08:33 "Re: [Tiff] LibTiff Suggestion, Need help to support application supplied JPEGTables.", by Joris Van Damme

Gerben,

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

  1. are you sure LibTiff reads back like it is supposed to, in this case?
  2. 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/
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