[NTG-context] Re: JPEG 2000 extensions

[Jim <zlists+context@jdvb.ca>]

Hi Hans,

On Sat, Jan 11, 2025 at 11:48 (+0100), Hans Hagen wrote:

> On 1/11/2025 1:47 AM, Jim wrote:
>> Hi,

>> in .../tex/texmf-context/tex/context/base/mkiv/grph-inc.lua I see (at line
>> 333)
>>              ["jp2"]    = { list = { "jp2" } },

>> That is (AIUI) the proper extension for JPEG2000 (Part 1) images.
>> The JPEG2000 (Part 2) images I looked at have the same magic bytes as
>> listed in line 349 of that file.

>> AIUI, JPEG2000 (Part 2) images should have the extension .jpx.  Is it
>> possible to change line 333 to read

>>              ["jp2"]    = { list = { "jp2", "jpx" } },

>> ?

>> (I hope this is the only change needed.)

>> I may be the only (vocal) person using .JPX files right now, but in the
>> years to come, who knows how many people will use it?

>> Thanks.

>> Jim

>> P.S.  I know that I can use
>>          \definegraphictypesynonym [jpx] [jp2]
>> but in the interest of helping others who may run into this issue in
>> the future, ...

> did you check if pdf viewers can handle both? or is it just a suffix issue

All the PDF viewers (and other tools) I tried can handle JPX files.  These
include
- (ancient) Adobe acroread for Linux
- evince
- kpdf
- firefox and chromium's PDF viewers
- emacs' pdfview
- xpdf
- diffpdf
- ghostview
- mupdf
- qpdfview
- okular
- zathura
- xournal
- xournalpp
Admittedly, the list isn't exhaustive, but large enough that I think it
makes sense to provide support for JPX.

It is more than a suffix issue, as (for example) the "file" program knows
the different between Part 1 and Part 2 versions of JPEG2000 files.

Further, the tool I access to create Part 2 images from (ordinary) JPEGs
creates considerably smaller images than the tools I have to create Part 1
images (with no apparent loss of quality).  I do not know enough about the
differences to comment on the likelihood that a viewer will handle Part 1
but not Part 2, but I can say I haven't seen such a thing yet.

(In about a year and a half of using Part 2 images in a monthly newsletter
I edit, I have only had one person complain once about not being able to
see the images; this person is known to have ancient software on his
computer, and he only mentioned it once, which makes me think he used a
different program to look at the newsletter one month.)

Cheers.
                                Jim
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