On Tue, 17 Dec 2013, David Flanagan wrote:
>
> Once a large image is decoded and downsampled into a smaller
> ImageBitmap, the only thing that we can do with that ImageBitmap is to
> copy it into a Canvas, either for display to the end user (as an
> alternative to an <img>) or for re-encoding with Canvas.toBlob() (when
> creating thumbnails for large images). The motivation for this
> downsampling feature is memory use. But having to copy an ImageBitmap
> into a canvas in order to use it immediately doubles the amount of
> memory required. So for this reason, I also want to propose that
> ImageBitmap have a transferToCanvas() method akin to the
> transferToImageBitmap() and transferToImage() methods proposed at
> http://wiki.whatwg.org/wiki/WorkerCanvas.  transferToCanvas would
> transfer the image data into a new Canvas object and would neuter the
> ImageBitmap so that it could no longer be used.