Rotation exif data lost after resize

[metalaureate]

Does imageproxy preserve EXIF data? When users upload portrait photos under some conditions that haven't been able to nail down, they are rotated incorrectly after imageproxy has processed them, even though they render correctly in the browser natively.

I seem to be having the same problem as described here: http://stackoverflow.com/questions/13971491/captured-photo-automatically-rotated-during-upload-in-ios-6-0-or-iphone

Any ideas how to solve? Thanks!

[willnorris]

As far as I know EXIF data should be preserved. I certainly don't do anything to actively strip it out. If you can come up with a reproducible case, that would certainly be helpful. I haven't observed anything like this myself.

[metalaureate]

Here's an example:

http://s3.amazonaws.com/co.ifwe.heartbeat.photos/bd6c353f-ce72-4bac-84b8-9ad32e54fc2a.jpg

vs.

http://domain:8080/600/http://s3.amazonaws.com/co.ifwe.heartbeat.photos/bd6c353f-ce72-4bac-84b8-9ad32e54fc2a.jpg

[willnorris]

Interesting. So when you proxy it with no resizing, it is oriented properly: http://pulseconnection.com:8080//http://s3.amazonaws.com/co.ifwe.heartbeat.photos/bd6c353f-ce72-4bac-84b8-9ad32e54fc2a.jpg

However, when I run it through my server it gets rotated, even with no resizing: https://willnorris.com/api/imageproxy/sYwItOwfiXif7JTX5qVF3j0YyoDMTblWn1h6O8M97YlA/https://s3.amazonaws.com/co.ifwe.heartbeat.photos/bd6c353f-ce72-4bac-84b8-9ad32e54fc2a.jpg

Definitely something I'll need to dig into.

[metalaureate]

I think you must be inadvertently stripping out the EXIF tags. Is there maybe an option to preserve them? I will experiment with node-exif to verify and post back. Otherwise I have to store the correct orientation before the photo is uploaded and apply the rotation programmatically--lame! :)

[willnorris]

So yeah, the image decoding and encoding process is definitely dropping EXIF tags. I confirmed this by parsing out the tags before and after transform, but this is also discussed at golang/go#4341 and golang/go#12202.

Ideally, I'd want to completely preserve EXIF data through the transform, but that seems to be difficult since most libraries only support parsing the data, but not writing it back out (from what I can see). The best we can probably do is to just apply the appropriate transform ourselves to orient the image properly, similar to what camlistore does.

Incidentally, this also revealed a separate bug (#64), so that's kinda nice.

[metalaureate]

All of us resizing mobile phone uploads will be grateful for the orientation fix. If I weren't such a noob I'd gladly propose the fix myself.

[willnorris]

You can see this live with the test image noted in the comments above at https://willnorris.com/api/imageproxy/300x,sYwItOwfiXif7JTX5qVF3j0YyoDMTblWn1h6O8M97YlA/https://s3.amazonaws.com/co.ifwe.heartbeat.photos/bd6c353f-ce72-4bac-84b8-9ad32e54fc2a.jpg