Incorrect image transformation for few EXIF orientations

[davpsh]

The problem is reproduced on any version of the module.

I tested auto-rotation using an image with all possible EXIF orientations and found that some of them are not handled (transformed) correctly.

Here is a list of EXIF orientations from my tests with handle results and original image without EXIF orientation:

ID	Orientation	Image	Correctly transformed
1	Horizontal (normal)	orientation-1	✔️
2	Mirror horizontal	orientation-2	✔️
3	Rotate 180	orientation-3	✔️
4	Mirror vertical	orientation-4	✔️
5	Mirror horizontal and rotate 270 CW	orientation-5	✔️
6	Rotate 90 CW	orientation-6	❌
7	Mirror horizontal and rotate 90 CW	orientation-7	✔️
8	Rotate 270 CW	orientation-8	❌

[davpsh]

After some research, I found that the problem is more complex than few incorrect transformations.

Presented data are invalid and should be ignored.
I'll try to describe problem detailed as soon as possible.

I'll close referenced PR that doesn't fixes problem.

[ericnograles]

Thanks @davpsh -- if you have sample images that you can share, I can help troubleshoot this

[mei23]

Maybe the images published below are useful.

https://github.com/recurser/exif-orientation-examples
Landscape_[0-8].jpg

In my test, 2-8 seems to give wrong results.

[otaviosoares]

I fixed it here otaviosoares@31c6a93

It's a very poor implementation tho. I wanted to open a PR but I didn't have the time.

[tamaina]

Is there any progress? Or should I fork it?

[tamaina]

I forked: https://github.com/misskey-dev/browser-image-resizer

[ericnograles]

Will take a look at these, just bumped the library to the latest ExifReader so I'm wondering if the old one had some idiosyncracies.

[ericnograles]

@davpsh Looks like it may have been the older version of ExifReader we were using. I see the autoRotate transformations working (used your samples above):

90 CW

270 CW

If you grab the latest from NPM (v2.3.0) it should reflect these changes. lmk if you continue to see any issues, thanks!

[ericnograles]

Correction, latest is v2.3.2

[ericnograles]

Update: It appears we may not need ExifReader anymore, all browsers should now auto rotate images based on their EXIF. Will be testing a branch without ExifReader so we can really pare down the size of this library https://aws.amazon.com/blogs/machine-learning/how-an-important-change-in-web-standards-impacts-your-image-annotation-jobs/

The above was "fixed" because orientation from ExifReader would never resolve (it's now promise-y when you directly load a file) and it would never pass in the orientation value. And because my browser automatically rotates based on EXIF above, it should always resolve.

TL;DR: It appears web standards have saved us, we may not need ExifReader anymore.

[ericnograles]

Tested across all browsers, all engines autoRotate by default, exifreader and related logic removed.