Quality issue rejected images

These appear pretty dark to me, and looking at the histogram confirms the highlights and whites have very little information in them.  I know these are illustrations and not photos, but I don't think these would print well which would be a factor.

I think if you zoom in on the structures, there are some angles in there that have imperfections in them and other structures that appear misshapen or appear out of no where.  I think AI is getting much better about this, but it's still noticeable in these illustrations.

I hope you have better luck with future submissions!