[whatwg] Add EXIF metadata support in Canvas.toBlob?

Mark Callow callow.mark at artspark.co.jp
Thu Jun 13 20:06:12 PDT 2013

On 2013/06/08 5:42, David Flanagan wrote:
> [A related, but perhaps too ambitious, proposal is to allow direct
> read/write access to EXIF metadata via HTMLImageElement.  The primary
> use case for read access is to enable web apps to trivially determine
> when, where, and how a photo was taken and also to determine
> authorship and copyright information for an image.  The primary use
> case for write access might be for selectively stripping metadata. It
> would be nice to be able to protect user privacy with code as simple
> as |delete image.metadata.geolocation| for example.]
I enthusiastically second this. I think the primary use case is to make
it trivial for JS to be able to orient an image according to its EXIF
orientation when displaying it on the page. And this use case is huge.
The vast majority of cameras today tag images with the camera's
orientation when a picture is made.  Today you have the following
choices in order to have the image displayed correctly:

 1. create a copy of the image rotated to a top-left orientation
 2. manually apply a CSS style that rotates the image according to its
    specific orientation
 3. A hack using BinaryBlobs, extensive knowledge of the EXIF metadata
    format and I don't know what else.

None are appealing.



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