[whatwg] Image resize API proposal

David Levin levin at google.com
Tue May 25 11:39:18 PDT 2010

I've improved the accuracy of the canvas (resize/copy/rotate) perf test:

Here are some results in a similar format to what Mike posted (

Firefox 3.7a4 (no D2D)

Direct image copy: 39ms
Indirect copy with (via ImageData): 160ms
Copy with 2x scale: 646.5ms
Copy with 0.5x scale: 42.5ms
Copy with rotate: 358ms

Firefox 3.7a4 (D2D)

Direct image copy: 115ms
Indirect copy with (via ImageData): 365.5ms
Copy with 2x scale: 246ms
Copy with 0.5x scale: 48.5ms
Copy with rotate: 100.5ms

Chrome (45376)

Direct image copy: 32.5ms
Indirect copy with (via ImageData): 207.5ms
Copy with 2x scale: 378.5ms
Copy with 0.5x scale: 27.5ms
Copy with rotate: 367ms

While the GPU does help in some scenarios, unfortunately it must still take
some time to do its work, so it doesn't enable us to do sync apis that don't
hang the UI.

Feel free to run the test yourself and look at the code.

Best wishes,
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