[whatwg] toDataURL image/jpeg composition

Charles Pritchard chuck at jumis.com
Thu Dec 2 15:06:46 PST 2010

Currently, Firefox and Safari output image/jpeg in a way that differs 
from the spec:

As Philip quotes:
"For image types that do not support an alpha channel, the image must be
composited onto a solid black background using the source-over operator, and
the resulting image must be the one used to create the data: URL."

I'd prefer the spec were followed. In a similar case, I have noticed 
with getImageData that OS X clients do
not always follow the spec when it comes to color management.

Anyway, I'm trying to see that image/jpeg is implemented across browsers:
this current divergence from the spec means delays for other canvas 
implementations waiting on a resolution.

Is there a policy decision out from Apple / Mozilla about this 
particular technical issue?

I'd prefer to see a change in subsequent releases of those browsers, and 
stay with the current standard as written.


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