Hey just wondering if its permitted to upload an image which a pixiv artist has deleted by has been found by other means. I use the SauceNAO premium features a lot which permits users to see a gallery every picture an artist has uploaded even if they have deleted it. Reverse-image searching these thumbnails can then turn up the image on other boorus or Google images.
Can this be uploaded? If so, then would would be the proper source attribution; the 404'd pixiv page or the booru/location which the images was located?