AWARE [SYSTEMS] Imaging expertise for the Delphi developer
AWare Systems, Imaging expertise for the Delphi developer, Home TIFF and LibTiff Mailing List Archive

LibTiff Mailing List

TIFF and LibTiff Mailing List Archive
May 2017

Previous Thread
Next Thread

Previous by Thread
Next by Thread

Previous by Date
Next by Date

Contact

The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems



Valid HTML 4.01!



Thread

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 18:32 "Re: JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka

Unfortunately no.

If we set PHOTOMETRIC_RGB and COMPRESSION_JPEG then libtiff retains the
libjpeg's default h/v_samp_factors set to 1, which result in
full-resolution chroma and much larger files. Neither it supports
overriding them for anything other than PHOTOMETRIC_YCBCR. There is a
comment in the code that says "TIFF 6.0 forbids subsampling of all other
color spaces".

First, I doubt that this comment is correct. I looked at the TIFF 6.0 spec
and it does not seem to have any restrictions on the JFIF stream internals,
only on the TIFF metadata. So why couldn't the encapsulated JFIF data be
chroma subsampled?

Second, even if such TIFF wouldn't be a standard baseline TIFF, it seems
that libtiff would be able to read it without any problems, so why can't I
explicitly generate such streams? I'll try to compile a modified libtiff
version that would lift this restriction and see if it works later.


On Thu, May 11, 2017 at 9:15 PM, Kemp Watson <kemp@objectivepathology.com>
wrote:

> Isn’t that just libtiff built with libjpeg?
>
>
> *W. Kemp Watson*
> *kemp@objectivepathology.com <kemp@objectivepathology.com>*
>
>
> *Objective Pathology Services Limited*
>
> 8250 Lawson Road
> Milton, Ontario
> Canada  L9T 5C6
>
> www.objectivepathology.com
> tel. +1 (416) 970-7284
>
>
> From: <tiff-bounces@lists.maptools.org> on behalf of Yakov Galka <
> ybungalobill@gmail.com>
> Date: Thursday, May 11, 2017 at 1:35 PM
> To: TIFF mailing list <tiff@lists.maptools.org>
> Subject: [Tiff] JPEG compressed RGB tiled TIFF with chroma subsampling
>
> Dear all,
>
> Is there a way to create a tiled tiff such that each individual tile is
> chroma sub-sampled but the responsibility on that YCC conversion and
> subsampling is on the JPEG encoder/decoder rather than the target
> application?
>
> Thanks,
> --
> Yakov Galka
> http://stannum.co.il/
> _______________________________________________ Tiff mailing list:
> Tiff@lists.maptools.org http://lists.maptools.org/mailman/listinfo/tiff
> http://www.remotesensing.org/libtiff/
>



-- 
Yakov Galka
http://stannum.co.il/