Most prioritized, always provides images in original quality. In italic — not 100% sure, but no cases to put it lower.
- Inkbunny ;
- Patreon (unsure about public posts);
- Pillowfort (seems to provide originals, allows 3rd side images embed);
- Pixiv (but sometimes fetch receives JPG instead of PNG).
Original image can be obtained, if artist allowed it in any way. Same priority, as previous, but should be checked.
- DeviantArt — if download explicitly allowed ;
- FurAffunity — if any image dimension is larger than 1280 (when image initially uploaded, it’s compressed to JPG and 1280x1280 at most, but can be reuploaded again, then it won’t be compressed);
- VK — image can be uploaded as “document”, usually parallel upload (click on second image).
Sometimes image is present in original quality, sometimes not. It’s not upon artist choice (at least, directly).
- DeviantArt — sometimes image can be zoomed in and it will result in original quality;
- Twitter — if naturally PNG (url edit does not count!) and if any image dimension is not equal to 1024/2048/4096;
- Tumblr — naturally PNG under 1280x1960 for pics with old url format and under 2048x3072 (any format) for newer.
Not explicitly accessible, missing from the UI.
- DeviantArt — token can be omitted, provided by gallery-dl or ADUp DeviantArt userscript;
- DeviantArt — sometimes original image will be provided in login page background, if opened from the image page;
- Portfolio.commishes — see here ;
- Tumblr — see here — for newer pics dimensions in URL can be edited (sometimes output will be forced JPEG), for older — reblog + dump blog
- ych.art — append
?width=20000&height=20000 to the file link.
Listed roughly in quality order (may be duplicated based on the case):
- Twitter — under 1024x1024, 2048x2048 or 4096x4096, JPG if no transparency;
- DeviantArt (“exploit”) — “intermediary” exploit for older images, under 6MPx, original format — see here;
DeviantArt (“exploit”) — newer images under 6MPx can be retrived partially and combined later using “crop” API endpoint. However, lower right corner can be blurred; now seems to always return upscaled publicly available image.
- Tumblr (new image url format) — under 2048x3072, original format;
- DeviantArt (““exploit””) — thumb size upon artist choice (under 1920 pixels width), original format if thumb url edited to match, also 100% quality JPG is possible — see here;
- VK — under 2560x2160 (except very old images), always JPG;
- Tumblr (old image url format) — under 1280x1920, can be JPG if image is too large;
- DeviantArt — thumb size upon artist choice (under 1920 pixels width), JPG if no transparency;
- ych.art — under 1600x1280, crisp zoom, original format;
- FurAffunity — under 1280x1280, JPG if no transparency;
- Portfolio.commishes — width can be 700, 960, 1920px, can be upscaled, crisp zoom, always indexed PNG;
- instagram — somewhat under 1024-1600px, always heavily compressed JPG.
- added more info about deviantart *sigh*
- added info about exploit on ych.art