Blurry artwork images on partner profile pages

[starsirius]

Reported in https://artsy.slack.com/archives/C02CAB1KW/p1513010048000134

The image looks sharp on the individual artwork page and in CMS, but on the partner profile page works and artists tab, it appears blurry. To reproduce, compare

https://www.artsy.net/artwork/jeff-keen-secret-comic-number-4
and the same image on
https://www.artsy.net/hales-gallery/works
https://www.artsy.net/hales-gallery/artist/jeff-keen

Looks like the image is up-scaled a few pixels.