Convert Proof images to WebP ?

[raphodn]

Story

We currently store as-is the proof images that we receive (and we also create a thumbnail, thanks to #340 )

The frontend currently converts on the fly the user images to .webp before sending them to the server. done here
But the mobile integration sends the raw images.

Should we convert images in the backend ? Should we push the mobile to convert locally as well ?

Why WebP ?

• reduces by x3-4 (?) the weight of the image, without impact on the quality (?)
• https://caniuse.com/webp

Alternatives to WebP ?

AVIF

• https://caniuse.com/avif (not as widesspread as webp)

[raphael0202]

For information, we get a ~30% file size decrease when using webp: https://developers.google.com/speed/webp.

[raphodn]

When using the web app "proof upload" workflow, I get a decrease by a factor of 6-7 👀

	JPG 100%	WebP 80%	JPG 80%
Stats	.jpg 4608x3456 7.5 MB	.webp 4608x3456 987 kB	.jpg 4608x3456 1.8 MB
Raw image	https://ibb.co/HF4RrQ6	https://ibb.co/n67J75R	https://ibb.co/gdPWqHY
Zoomed in screenshot

[raphael0202]

That's impressive!

[raphodn]

As discussed, priority is rather to have the mobile app send us a .webp directly (will speed up contribution, and bandwith).
Edit: issue created here: openfoodfacts/smooth-app#5952

We can postpone to later the decision to convert in the backend the non-webp images that we receive.

[raphodn]

Related: it doesn't seem we retain EXIF data (both from WebP images coming from the web app, and JPEG images coming from the mobile app).

I created an issue related to the frontend to understand why (i thought EXIF was kept): fengyuanchen/compressorjs#196

Edit : moving the discussion here: openfoodfacts/open-prices-frontend#1092