gnuplot-beta

SVG pixelation (was pdfcairo terminal seams between bars in the colorbox)

[Ethan A M. <me...@uw...>]

> The svg terminal currently produces images with no image-rendering
> annotations. And most browsers render images with bilinear interpolation
> by default, which makes low-res images look very wrong.

> My friend figured out how to get svg to work
> in both firefox and chrome, and I'm attaching a patch that does that.
> The description is in the patch.

[snip patch that adds attributes
 <image image-rendering='crisp-edges' style='image-rendering: pixelated' ...
]

Thanks.  That's a good start.

As tested here those attributes are indeed honored by firefox and chrome.
Mixed success on other svg handling programs.

Works:
   chrome
   firefox
   inkscape/inkview
   ImageMagick

Fails:
   konqueror
   LibreOffice / soffice
   gwenview
   gimp

Unknown (did not try):
   eog
   geeqie

	Ethan

Re: SVG pixelation (was pdfcairo terminal seams between bars in the colorbox)

[Dima K. <gn...@di...>]

Ethan A Merritt <me...@uw...> writes:

> As tested here those attributes are indeed honored by firefox and chrome.
> Mixed success on other svg handling programs.

I'm guessing that adding support for either image-rendering=crips-edge
or image-rendering=pixelated into librsvg and QSvg would make all of
these work. But it looks like these two libraries simply don't support
either option yet.

I'll file feature-request bug reports for those two projects.

But the patch should probably still go in: supporting firefox and chrome
is much better than supporting nothing.

Re: SVG pixelation (was pdfcairo terminal seams between bars in the colorbox)

[Ethan A M. <me...@uw...>]

On Sunday, 18 June 2023 23:55:07 PDT Dima Kogan wrote:
> Ethan A Merritt <me...@uw...> writes:
> 
> > As tested here those attributes are indeed honored by firefox and chrome.
> > Mixed success on other svg handling programs.
> 
> I'm guessing that adding support for either image-rendering=crips-edge
> or image-rendering=pixelated into librsvg and QSvg would make all of
> these work. But it looks like these two libraries simply don't support
> either option yet.

I looked into it a bit further.

The thing is, the two hinting properties you found are not part of the
SVG standard (version 2).  They are instead CSS style hints to the browser.
Chrome and Firefox apparently dive into an included SVG file and extract
the CSS style hints from there. SVG-aware programs that are not browsers,
like inkscape or gimp, could do the same but the motivation for doing
so would come from imitating Chrome or Firefox rather than adhering to
the SVG standard.  Inkscape does, but gimp doesn't. 

> I'll file feature-request bug reports for those two projects.
> But the patch should probably still go in: supporting firefox and chrome
> is much better than supporting nothing.

For me personally, the support from inkscape is just as important as
from the browsers.  I use it to prepare figures for publication.
And it's still true that you can work around this
by using "with image pixels" for gnuplot heat maps. 

What about lobbying the SVG working group to add an equivalent
to the SVG spec?  All the various support libraries would then
eventually fall in line.  As of SVG 2.0 you only get a choice
between "optimizeSpeed" and "optimizeQuality", both of which
are so vague as to be useless for our purpose.

    https://svgwg.org/svg2-draft/painting.html#ImageRendering

Re: SVG pixelation (was pdfcairo terminal seams between bars in the colorbox)

[Dima K. <gn...@di...>]

Ethan A Merritt <me...@uw...> writes:

> I looked into it a bit further.
>
> The thing is, the two hinting properties you found are not part of the
> SVG standard (version 2).  They are instead CSS style hints to the browser.
> Chrome and Firefox apparently dive into an included SVG file and extract
> the CSS style hints from there. SVG-aware programs that are not browsers,
> like inkscape or gimp, could do the same but the motivation for doing
> so would come from imitating Chrome or Firefox rather than adhering to
> the SVG standard.  Inkscape does, but gimp doesn't. 
>
>> I'll file feature-request bug reports for those two projects.
>> But the patch should probably still go in: supporting firefox and chrome
>> is much better than supporting nothing.

> For me personally, the support from inkscape is just as important as
> from the browsers.  I use it to prepare figures for publication.
> And it's still true that you can work around this
> by using "with image pixels" for gnuplot heat maps. 
>
> What about lobbying the SVG working group to add an equivalent
> to the SVG spec?  All the various support libraries would then
> eventually fall in line.  As of SVG 2.0 you only get a choice
> between "optimizeSpeed" and "optimizeQuality", both of which
> are so vague as to be useless for our purpose.
>
>     https://svgwg.org/svg2-draft/painting.html#ImageRendering

That's interesting. Not sure what it means for us in practical terms.
The patch in this thread should cover most browsers. Most non-browser
applications I've seen use rsvg: bug report here

  https://gitlab.gnome.org/GNOME/librsvg/-/issues/985

I guess QT has its own implementation too; I ran out of steam, and
haven't pestered them. I don't know what libreoffice does, but it does
the right thing on my machine. And I don't know how to lobby the SVG
working group.

I would merge the patch in this thread, maybe file a bug report against
QSvg, and move on.

Re: SVG pixelation (was pdfcairo terminal seams between bars in the colorbox)

[Dima K. <gn...@di...>]

Dima Kogan <gn...@di...> writes:

> Most non-browser applications I've seen use rsvg: bug report here
>
>   https://gitlab.gnome.org/GNOME/librsvg/-/issues/985

Just an FYI. The rsvg upstream has fixed the issue, and closed the bug
report (allegedly; I couldn't easily try it). But if it's fixed, then
most non-browser client applications will show our pixelated images.

Re: SVG pixelation (was pdfcairo terminal seams between bars in the colorbox)

[Ethan A M. <me...@uw...>]

On Thursday, 13 July 2023 09:26:25 PDT Dima Kogan wrote:
> Dima Kogan <gn...@di...> writes:
> 
> > Most non-browser applications I've seen use rsvg: bug report here
> >
> >   https://urldefense.com/v3/__https://gitlab.gnome.org/GNOME/librsvg/-/issues/985__;!!K-Hz7m0Vt54!k39HeEQ9zt5kuFFtV54jBNfoBJvfqILRmzHarDU6bxyPm-2JXE1ruwmzZkCnARQ0hIggFA3zaJa59Jm0EojHJg$ 
> 
> Just an FYI. The rsvg upstream has fixed the issue, and closed the bug
> report (allegedly; I couldn't easily try it). But if it's fixed, then
> most non-browser client applications will show our pixelated images.

Except, apparently, on MacOS.
See discussion on 
   https://sourceforge.net/p/gnuplot/feature-requests/558/
   https://www.userlandia.com/home/2021/11/the-mystery-of-mac-os-mangled-image-interpolation-implementation

I'm in the process of combining suggestions from
Hiroki Motoyoshi (problems with MacOS)
and Alexander Täschner (problems with MSVC)
to hopefully end up with something that works for everyone.

    thanks

	Ethan