How are images flagged to need Replacement?

[j7n]

I've noticed a few poor quality images on site, and some others greyed out and marked as needing Replacement. They were not quite as bad as the ones that I noticed were not marked. I suppose a moderator hasn't had interest in those artists and hasn't looked at the pictures. How does an image get flagged?

[McVicar]

If you notice a not so optimal picture then you can report it, it takes then a few days until it is marked as makings .... then still a few days wait until the original creator it possibly improves, happens after a week nothing then You can download your improved version. You get no news when it is released as reported therefore after a few days to check whether it is already in it. At very old cover the veile years were loaded up the guidelines not yet as strict as hay therefore some pictures are not so beautiful and must be exchanged
cheers
McVicar