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[Bug 11431] should mention that .toDataURL() for image/jpeg acts as if the image was composited against black

From: <bugzilla@jessica.w3.org>
Date: Wed, 15 Dec 2010 07:23:17 +0000
To: public-html-bugzilla@w3.org
Message-Id: <E1PSlhl-0001fH-R8@jessica.w3.org>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=11431

--- Comment #5 from Noel Gordon <noel.gordon@gmail.com> 2010-12-15 07:23:17 UTC ---
(In reply to comment #4)

My results running http://philip.html5.org/demos/canvas/jpeg-alpha.html

Firefox 3.6.12 win32
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,63,255,1)
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,63,255,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,62,255,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,62,255,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(1,59,255,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(1,59,255,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(0,0,0,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(0,0,0,1)

Chrome 10 dev win32
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,63,255,1)
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,63,255,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,62,255,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,62,255,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(1,61,255,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(1,61,255,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(0,0,0,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(0,0,0,1)

Safari 5.0.2 win32
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,63,255,1)
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,63,255,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,62,255,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,62,255,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(1,61,255,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(1,61,255,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(255,255,255,1) 
<-- bug composites on white
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(255,255,255,1)  

Opera 10.63 Win32
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,64,253,1)
 Input: rgba(0,63,255,1.0); format: image/jpeg; output: rgba(0,64,253,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,63,252,1)
 Input: rgba(0,63,255,0.5); format: image/jpeg; output: rgba(0,63,252,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(0,56,244,1)
 Input: rgba(0,63,255,0.1); format: image/jpeg; output: rgba(0,56,244,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(0,0,0,1)
 Input: rgba(0,63,255,0.0); format: image/jpeg; output: rgba(0,0,0,1)

For alpha != 0.0
 results are the same neglecting rounding effects.
For alpha == 0.0
 composites on black (except safari, that is a safari bug).


Philip, can you add your full results for IE9?

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Received on Wednesday, 15 December 2010 07:23:20 UTC

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