2018.02.21 18:56 "Re: [Tiff] Pull request to add ZStandard/ZSTD codec", by Kemp Watson

Hi Leonard - yes, found it in my spam, of course…

This clarifies the TIFF situation a lot, thanks. I’ll need to read up on TIFF/EP.

Your point about the registry is well taken.. I, and others, have registered tags in the private area. This is largely because there’s been no real mechanism to register new public tags (and, for backwards-compatibility, maybe there should not be..), but that doesn’t negate the fact that they should be _private_.

If the spec is in the hands of ISO, what do you think of turning over the maintenance of the private tags to them? The current danger is that without access to the existing list, tags might be double-used and potentially make a real mess.

W. Kemp Watson

kemp@objectivepathology.com

Objective Pathology Services Limited

8250 Lawson Road
Milton, Ontario
Canada L9T 5C6

www.objectivepathology.com
tel. +1 (416) 970-7284

On 2018-02-18, 10:14 AM, "Leonard Rosenthol" <lrosenth@adobe.com> wrote:

>Kemp - I thought I answered this already, but maybe my message didn't >make it to the list (or to you). Here it is again (sorry for any >duplicated posts):

>
>

>Adobe has worked with various ISO committees to make (most of) the TIFF >specification an open standard through that process. I believe that >TIFF/EP (ISO 12234-2) encompasses all of the core TIFF spec as well as >many extensions - and that it does not prohibit others. If there are >specific things that TIFF/EP prohibits that are currently in use, that >would be the place to take your requirements as we see that as the open >standard version of TIFF.

>

>As for the registry - I am not familiar with the contents of the TIFF >registry, but as the maintainer of the equivalent for PDF, I can speak to >why we haven't done that for the PDF registry and perhaps the same >applies. In the case of the PDF registry, we cannot release the >information publicly as it contains information that was provided to >Adobe directly and without any permission to make it public - as such, it >may contain "trade secrets" or other information that we cannot disclose.

>
>Hope that helps.
>
>Leonard
>
>-----Original Message-----
>From: Kemp Watson [mailto:kemp@objectivepathology.com]
>Sent: Sunday, February 18, 2018 8:37 AM

>To: rleigh@codelibre.net; Leonard Rosenthol <lrosenth@adobe.com>; Even >Rouault <even.rouault@spatialys.com>

The previous system required no review to request or allocate private tags. Re new tags or compression schemes, including ZSTD, do note that the resultant files may NOT have a .tif or .tiff file extension, as the codec is not part of Baseline TIFF 6.0.

One of the issues, however, with that open approach, is the duplication of codec tags. There are at least three now for JPEG 2000; I registered PNG and JPEG XR some years agoŠ by necessity in the private tag area, as there was no one to talk to about official adoption, Adobe did not

>res