Doesn't work with our image.
We wanted to make sure the compression algorithm for lossless was powerful enough (30% announced sounds quite low in comparison to tools like TinyPng), so we ran a trial on one specific product.
We optimized all images, lossless at first, then a few with lossy compression.
The app says xx% compression, but Google Page Speed says nothing changed.
Ok, we downloaded the so said "compressed" images, from Shopify (changing the ?variable to make sure we have the latest version)... Nothing changed.
So, let's try to download the preview image displayed on screen that is supposed to show a comparison between the old and the new image.
Surprise... Same image, same size.
The comparison tool is very fancy, but both images are not on the same layer, the second image has a small offset of a few pixels, so it gives the impression the image is not identical, but it is.
Again, it might just be a bug, but the fact the tool says the image was compressed by "xx%", and that the comparison tool second image is offset a bit is not reassuring.
I'm suspending my judgment temporarily. We've been in touch with the developers and it looks like our image are already too optimized for their app to have any significant effect on one hand, and that Shopify is messing up with optimized images (increasing their size) on its end.
For now, my first conclusion is that this app is pointless for those who know how to save their images (photoshop, gimp, or recompressed with online tools like TinyPNG) because Shopify already has its own algorithm.
Since Shopify algorythm increase the size of overoptimized images, negating the benefit of this app, it sounds pointless.
See here about image compression issues with Shopify: https://ecommerce.shopify.com/c/ecommerce-discussion/t/shopify-image-quality-optimization-round-2-with-stats-38-improvement-304813
We're in touch with the developpers, if something come up, I'll update my review;
Until then: I do not recommend the app to merchants already saving their images for internet use with proper comrpession.