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From: Lars Ingebrigtsen <larsi@gnus.org>
To: "Clément Pit--Claudel" <clement.pitclaudel@live.com>
Cc: 22253@debbugs.gnu.org
Subject: bug#22253: Background of transparent PNG images uses default background color, instead of current one
Date: Thu, 01 Aug 2019 18:59:55 +0200	[thread overview]
Message-ID: <87mugskeic.fsf@mouse.gnus.org> (raw)
In-Reply-To: <5680A252.8040109@live.com> ("Clément Pit--Claudel"'s message of "Mon, 28 Dec 2015 03:45:38 +0100")

Clément Pit--Claudel <clement.pitclaudel@live.com> writes:

> When no :background is specified for a transparent PNG, the background color of the 'default face is used. This causes aliasing effect to appear then e.g. the image is highlighted (transient-mark-mode).
>
> To reproduce (on latest emacs-25):
>
> * Save https://i.stack.imgur.com/BqrLK.png as ~/rooster.png
> * emacs -Q
>   M-: (insert #(" 🐤" 1 2
> 	  (display
> 	   (image :type imagemagick :file "~/rooster.png" :ascent center :mask heuristic :height 150))))
> * Notice that the picture looks perfectly antialiased against the default white background
> * C-x h
> * Notice the aliasing

The only way to fix this would be to re-generate the images whenever the
background colour of the image changes, I guess?  Or to support alpha
channels directly in the display engine, and I don't think we have
support for that?

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





  reply	other threads:[~2019-08-01 16:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-28  2:45 bug#22253: Background of transparent PNG images uses default background color, instead of current one Clément Pit--Claudel
2019-08-01 16:59 ` Lars Ingebrigtsen [this message]
2019-09-26 16:22   ` Lars Ingebrigtsen

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