GNU bug report logs - #27086
perhaps always use a white background when viewing transparent PNGs etc.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: bug-gnu-emacs <at> gnu.org
Subject: perhaps always use a white background when viewing transparent PNGs
 etc.
Date: Fri, 26 May 2017 21:37:11 +0800

With this color,
(add-to-list 'default-frame-alist '(background-color . "DarkSlateGray"))
looking at
http://jidanni.org/location/directions/qingfujie_slope.png
is tough for the words outside the graph.
So perhaps always use a white background when viewing transparent PNGs, etc.

Message #8 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 27086 <at> debbugs.gnu.org
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Fri, 02 Jun 2017 23:25:17 -0400

[Message part 1 (text/plain, inline)]

積丹尼 Dan Jacobson <jidanni <at> jidanni.org> writes:

> With this color,
> (add-to-list 'default-frame-alist '(background-color . "DarkSlateGray"))
> looking at
> http://jidanni.org/location/directions/qingfujie_slope.png
> is tough for the words outside the graph.

I don't see any problem.  It looks like that png has a non-transparent
white background?

[bug-27086-default-frame.png (image/png, attachment)]

[bug-27086-gray-frame.png (image/png, attachment)]

[Message part 4 (text/plain, inline)]

> So perhaps always use a white background when viewing transparent PNGs, etc.

Seems to me if a PNG needs a certain background colour to be readable,
then it shouldn't be transparent.  What if you had a transparent PNG
with white words?

Message #11 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: npostavs <at> users.sourceforge.net
Cc: 27086 <at> debbugs.gnu.org
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Wed, 07 Jun 2017 03:40:33 +0800

[Message part 1 (text/plain, inline)]

Here's what I see when I save
http://jidanni.org/location/directions/qingfujie_slope.png
to disk and use C-x C-f on it with my
(add-to-list 'default-frame-alist '(background-color . "DarkSlateGray"))
color.

[d.jpg (image/jpeg, attachment)]

Message #14 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 27086 <at> debbugs.gnu.org, Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 04:27:10 +0200

積丹尼 Dan Jacobson <jidanni <at> jidanni.org> writes:

> Here's what I see when I save
> http://jidanni.org/location/directions/qingfujie_slope.png
> to disk and use C-x C-f on it with my
> (add-to-list 'default-frame-alist '(background-color . "DarkSlateGray"))
> color.

I can't reproduce this on current master using:

0. emacs -Q
1. Evaluate:
(add-to-list 'default-frame-alist '(background-color . "DarkSlateGray"))
2. C-x 5 2
3. C-x C-f qingfujie_slope.png RET

Result is a gray background, but the image displays just fine.

Are you still seeing this?

Best regards,
Stefan Kangas

Message #17 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: 27086 <at> debbugs.gnu.org, Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 12:23:24 +0800

>>>>> "SK" == Stefan Kangas <stefan <at> marxist.se> writes:

SK> Result is a gray background, but the image displays just fine.

Well I got rid of all the transparency on my website. So you will need a
different transparent test file.

Message #20 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Kangas <stefan <at> marxist.se>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 27086 <at> debbugs.gnu.org, Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 06:29:50 +0200

Dan Jacobson <jidanni <at> jidanni.org> writes:

> SK> Result is a gray background, but the image displays just fine.
>
> Well I got rid of all the transparency on my website. So you will need a
> different transparent test file.

Could you please provide an image where you can reproduce this issue?

Best regards,
Stefan Kangas

Message #23 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: 27086 <at> debbugs.gnu.org, Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 12:59:33 +0800

[Message part 1 (text/plain, inline)]

OK. Let's start fresh.
Something I'm doing in https://www.jidanni.org/comp/configuration
makes

[N.png (image/png, attachment)]

[Message part 3 (text/plain, inline)]

render like

[Yuck.jpg (image/jpeg, attachment)]

[Message part 5 (text/plain, inline)]

just as ugly as it does in chromium.

But it looks great in firefox, and emacs -Q.
So there is something in my above configuration causing it to look ugly.

emacs-version "26.3"

Message #26 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 27086 <at> debbugs.gnu.org, Stefan Kangas <stefan <at> marxist.se>,
 Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 12:27:00 +0200

積丹尼 Dan Jacobson <jidanni <at> jidanni.org> writes:

> OK. Let's start fresh.
> Something I'm doing in https://www.jidanni.org/comp/configuration
> makes

I'm guessing it's an image rendered towards white, but with a
transparent background?  And you have a black background in your Emacs?

Then there's nothing we can do here -- the PNG itself is badly made
(instead of using alpha channels it's just marking pixels as either
fully transparent or fully opaque).

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #29 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: Stefan Kangas <stefan <at> marxist.se>
Cc: 27086 <at> debbugs.gnu.org, Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 23:33:40 +0800

>>>>> "LI" == Lars Ingebrigtsen <larsi <at> gnus.org> writes:
LI> you have a black background in your Emacs?

Yes.

LI> Then there's nothing we can do here -- the PNG itself is badly made
LI> (instead of using alpha channels it's just marking pixels as either
LI> fully transparent or fully opaque).

Well looks great in Firefox.
Firefox always does the right thing.

Message #32 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 27086 <at> debbugs.gnu.org, Stefan Kangas <stefan <at> marxist.se>,
 Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 18:00:43 +0200

積丹尼 Dan Jacobson <jidanni <at> jidanni.org> writes:

> LI> Then there's nothing we can do here -- the PNG itself is badly made
> LI> (instead of using alpha channels it's just marking pixels as either
> LI> fully transparent or fully opaque).
>
> Well looks great in Firefox.
> Firefox always does the right thing.

Sounds like Firefox defaults to white backgrounds on these images, but
if the PNG had been constructed the other way (towards black), then that
would have looked equally bad.

So it doesn't seem like there's anything we can do here.

Did you forward the original PNG file to the bug tracker?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #35 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 27086 <at> debbugs.gnu.org, Stefan Kangas <stefan <at> marxist.se>,
 Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Mon, 30 Sep 2019 00:08:30 +0800

Well then you are supposed to use a checkerboard pattern I suppose.
https://bugs.chromium.org/p/chromium/issues/detail?id=991197
Not just leave things up to chance so they look good for Mr. X, but not
when sent to Mr. X's boss or later during a conference.

(LI> Did you forward the original PNG file to the bug tracker?
Just use the latest attachment I added.)

Message #42 received at 27086 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: 積丹尼 Dan Jacobson <jidanni <at> jidanni.org>
Cc: 27086 <at> debbugs.gnu.org, Stefan Kangas <stefan <at> marxist.se>,
 Noam Postavsky <npostavs <at> users.sourceforge.net>
Subject: Re: bug#27086: perhaps always use a white background when viewing
 transparent PNGs etc.
Date: Sun, 29 Sep 2019 18:11:45 +0200

積丹尼 Dan Jacobson <jidanni <at> jidanni.org> writes:

> Well then you are supposed to use a checkerboard pattern I suppose.
> https://bugs.chromium.org/p/chromium/issues/detail?id=991197
> Not just leave things up to chance so they look good for Mr. X, but not
> when sent to Mr. X's boss or later during a conference.

Heh, I don't think so.  Most transparent images look nice.

> (LI> Did you forward the original PNG file to the bug tracker?
> Just use the latest attachment I added.)

Oh, I thought that PNG was to demonstrate how it looked in Emacs.  If
you want to look what it looks like with a checkerboard, open it in
gimp.

(Spoilers: It looks horrible.)

So there's no bug on Emacs' side -- the image is just badly made.
Closing.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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