Instagram compression destroys images exported by NegPy

[gonzalomorenorovetto]

When I try to upload images exported from NegPy to instagram, the compression destroys the image, with very big blocks/chunks of color. This happens with JPEG (tried from 70-100 quality) and also with PNGs. TIFFs where not recognized, but when exporting as TIFF, then importing to Darktable and exporting to JPEG, the same happens.

If the image is exported directly to JPEG from Darktable (inverted with negadoctor), without going through NegPy, the images retains its quality when uploaded to Instagram.

[marcinz606]

can't reproduce, posting exported images to instagram seems fine for me
https://www.instagram.com/35mm_z/

[gonzalomorenorovetto]

Nice feed btw!

[seanharding]

How do the file sizes compare? My experience is that if the file size is too large, Instagram over-compresses to compensate. Haven't tried this with any files from NegPy, though.

[gonzalomorenorovetto]

Thy are almost the same size, but tried with even 200kb files, 70% quality jpegs, 1080x1080, and instagram destroys them. But from Darktable, everything looks good.
Gonna try again and post samples

[gonzalomorenorovetto]

made the test with the same image: exported from negpy as jpeg 90, exported from darktable as jpeg 90, and a tiff from negpy exported from darktable as jpeg 90

I have random results: sometimes it gets destroyed, sometimes it doesn't. Sometimes is the image from darktable, sometimes the one from negpy.

So I only have Instagram to blame.

[seanharding]

Instagram compression is probably not literally random, but from the outside it feels like a black box. I've worked hard to try to find ways to prepare my images so they look good on IG, and I still only succeed about half of the time…