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Issue 831254 link

Starred by 1 user
Status: WontFix
Owner:
█ zakerinasab@chromium.org
Last visit > 30 days ago
Closed: Oct 11
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 2
Type: Bug

Blocking:
issue 634542



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Canvas round trip through toDataURL broken with transparency+jpeg+float16

Project Member Reported by junov@chromium.org, Apr 10 2018 
When encoding a canvas in float 16 format to a jpeg file, semi-tranparent pixels are not handled correctly

Steps:
1) start chrome with --enable-experimental-web-platform
2) run attached test

Result: Third column (corresponding to JPEG) looks lighter for the right half (semi-transparent pixels).

Expected: All squares look the same
toDataURL-color-managed-round-trip.html
1.4 KB View Download

Comment 1 by junov@chromium.org, Apr 10 2018 

Note: jpeg, does not encode the alpha channel.  We basically encode the result of compositing the semi-transparent image over black.  This should give results that are visually identical to this source canvas which has a black background.

Comment 2 by junov@chromium.org, Apr 23 2018

Status: Assigned (was: Untriaged)

Comment 3 by junov@chromium.org, Apr 23 2018 

IT is possible that this is not a bug, and just the result of "composite over black" happening in linear space, which might be expected behavior (TBD).

Comment 4 by zakerinasab@chromium.org, Sep 25

Blocking: 634542

Comment 5 by zakerinasab@chromium.org, Oct 11

Status: WontFix (was: Assigned)
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