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May 2017

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2017.05.11 17:35 "JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka
2017.05.11 18:15 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Kemp Watson
2017.05.11 18:32 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka
2017.05.11 18:45 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by <jcupitt@gmail.com>
2017.05.11 18:55 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Even Rouault
2017.05.11 19:37 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka
2017.05.11 20:48 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by <jcupitt@gmail.com>
2017.05.22 11:53 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka
2017.05.22 13:13 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by <jcupitt@gmail.com>
2017.05.22 13:39 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Bob Friesenhahn
2017.05.22 16:41 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka
2017.05.22 15:31 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Kemp Watson
2017.05.22 16:42 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka
2017.05.22 19:18 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Roger Leigh
2017.05.22 19:42 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka

2017.05.11 18:55 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Even Rouault

On jeudi 11 mai 2017 19:45:23 CEST jcupitt@gmail.com wrote:
> Hi, this took me a while to work out too.
> 
> Just set TIFFTAG_JPEGCOLORMODE to JPEGCOLORMODE_RGB. This is a
> pseudo-tag -- it means you are going to supply RGB data, but that the
> encoder is free to convert to YCBCR and subsample in the usual way.

Yes, for encoding, use both TIFFTAG_JPEGCOLORMODE  = JPEGCOLORMODE_RGB and  
TIFFTAG_PHOTOMETRIC = PHOTOMETRIC_YCBCR. By default this will use h_samp_factor = 
v_samp_factor = 2.

> 
> You need to set it on decompress too I think to make libjpg convert
> the YCBCR back to RGB for you.
> 
> John
> _______________________________________________
> Tiff mailing list: Tiff@lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/tiff
> http://www.remotesensing.org/libtiff/


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