2017.05.22 16:41 "Re: [Tiff] JPEG compressed RGB tiled TIFF with chroma subsampling", by Yakov Galka

On Mon, May 22, 2017 at 4:39 PM, Bob Friesenhahn < bfriesen@simple.dallas.tx.us> wrote:

Libtiff does provide dummy/abstraction interfaces, but they do result in increased resource consumption, loss of performance, and sometimes loss of original image quality, compared with use of lower-level interfaces which deliver more directly into the using application's preferred internal storage format.

The JPEG issue is a bit different from the rest (like number of samples, bitness or sample format) -- because the conversion to YCC is usually seen as a detail internal to the JPEG encoder. Thus it's problematic that it leaks to to the TIFF container level.

I would avoid those 8-bit RGBA interfaces because I do care for the higher bitness and non-RGB data in my applications. But, I expect my TIFF to be declared Photometric RGB and still have every tile compressed with YCC subsampled JPEG.

Yes, I did read the TIFF specification and that technical note before opening this thread, and I don't see such arrangement contradicting the spec.

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