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2005.03.29 16:08 "Re: tif_jpeg.c and 12bit JPEG Files", by Bob Friesenhahn
On Tue, 29 Mar 2005, Jean-Yves Le Ridant wrote: > > Yes, but the problem of a "clean" release > with jpeglib for 8 and 12 bits samples ? > As said by other contributors, I agree that's much a burden to carry. > JSAMPLE, JSAMPROW, GET_JOCTET .... that parse the code. > And 12 bits compression by jpeglib *must* be two pass mode ... > > I use Jpeglib v6 in the way of Joris, 12 bits CIELAB, > with JCS_UNKNOWN ... , and it work very fine. > The only matter, for a 'clean' release, is having 2 build of the Jpeglib, > includes/typedef, .... and it's a matter. > The less changes, would be having a 12 bits jpeglib build, > and feed 8 or 12 bits data in a 16 bits JSAMPLE ... ? That is what the "MK1" library currently does. However, last I heard, David Gilbert was off creating a dual interface version of the library so that 8 bit users would not pay the "penalty" of 16-bit JSAMPLE, but 8/12 bit users could still support 12 bits from one library. I have heard nothing regarding progress with this approach. To me, the 16-bit JSAMPLE is really only a performance impact for 8-bit users who expect to memcpy() directly to and from libjpeg's buffers. Applications which iterate through the JSAMPLE array in order to copy to/from their own format should see little performance difference. Bob ====================================== Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/