[APPROVED] [Category change] Image artifacts -> Meta

category jpeg_artifacts -> meta
category scan_artifacts -> meta
category lossy-lossless -> meta
category gif_artifacts -> meta

Link to request

JPEG artifacts was brought up a lot in topic #14678, and scan artifacts and lossy-lossless were also mentioned and are similar so I grouped them into this single request. I don't have a strong opinion on this myself, although I wouldn't mind if the above were added to the Meta category.

Thoughts?

Edit:

• (2017-11-21) Added gif artifacts <☆♪: forum #139602>

EDIT: The bulk update request #1393 (forum #139563) has been approved by @Hillside_Moose.

+1. These tags should be meta tags, because they describe aspects of the image file. jpeg_artifacts and lossy-lossless indicate that a visually destructive algorithm was used to compress the file. For scan_artifacts, scan is a meta tag already, and scan_artifacts specifies what type of scan it is (a poor one).

+1. Making these meta tags would make things easier when copying tags between parent/child posts. Copying the jpeg artifacts tag from a Twitter post to a Pixiv post is a common mistake.

+1. There's also gif artifacts (which should probably be renamed to "quantization artifacts", though gif is probably the only format currently uploadable that quantizes enough to be an issue, unless we're going to try to tag anything with banding, which is probably a bad idea).

The bulk update request #1393 (forum #139563) has been approved by @Hillside_Moose.