On Fri, 7 Jun 2013, David Flanagan wrote:
>
> I would like to propose the addition of a fourth argument [for
> toBlob()] (for the JPEG case only) that would specify EXIF metadata
> to be included in the JPEG blob. (I have not tried yet, but I'm
> assuming that we could define some suitable JSON serialization
> format for EXIF data. If not, then even allowing a binary blob of
> EXIF data as the fourth argument would be helpful.)
>
> The use case for this feature is image editing applications, like
> the Gallery app on FirefoxOS devices. Whenever that app crops or
> edits a photo it encodes the edited photo with Canvas.toBlob(), and
> the process strips all metadata from the photo. Reading EXIF data
> from a JPEG blob is relatively straightforward can can be done with
> JavaScript, but inserting EXIF data into an existing blob is much
> harder: this is a task that is best done when the JPEG blob is being
> created, which means that it is a feature that belongs in toBlob and
> can not be done efficiently with an external library.

On Fri, 7 Jun 2013, Jonas Sicking wrote:
>
> If someone goes through the work of defining an EXIF <-> JSON mapping
> then this is something I'd be interested to see added to the spec.
>
> It definitely would be nice to enable modifying EXIF metadata without
> having to re-encode the pixel data since that leads to loss of
> quality.

On Wed, 12 Jun 2013, Alexandre Morgaut wrote:
>
> We have a JS API for that in Wakanda
> http://doc.wakanda.org/Images/Image-Class/meta.303-660131.en.html
>
> It use the saveMeta() meta method to apply potential changes:
> http://doc.wakanda.org/Images/Image-Class/saveMeta.301-661057.en.html