Bad quality (JPEG Compression) when saving PNG

[super-ienien]

Hi,

I'm having some trouble with image quality on JIMP.
I just download some JPEGs and save them as PNGs :

Jimp.readAsync(url) .then(function (image) { return image.writeAsync("image.png") }

The quality of the PNG is bad comparing to the original JPEG. It's like I was saving it twice in JPEG. See the exemple here (you can see that additionnal JPEG artefacts are presents around the white letters in the PNG):

ORIGINAL JPEG

SAVED PNG

[oliver-moran]

These aren't methods from this library:

Jimp.readAsync(url) ... image.writeAsync ...

How are you calling them?

[super-ienien]

Sorry, i'm using promisification functionnality of bluebird. So readAsync ad writeAsync are the promisified version of read and write method from Jimp.

[oliver-moran]

I'm doing a release in a few days. That will have some fixes in it, could you check again then?

[super-ienien]

I don't have time to test it again but i think it's due to the pngjs package more than Jimp

[oliver-moran]

Yes, definitely to do with pngjs. I'll keep an eye on it and if there's improvement to that library I'll pull it in. Thanks for logging it.

[oliver-moran]

Tested again after updating pngjs. Issues still presents.

[oliver-moran]

Suspect same as this issue: #134

[hipstersmoothie]

still an issue

[hipstersmoothie]

jpeg-js/jpeg-js#17