Was about to post this idea myself, but then this one floated to the top. Don't think it's necessary to say that selected art should be within 10%, though- I'm thinking Bliss should choose whatever art is closest to the preferred size, maybe with the option of giving some preference to larger or smaller art so that, if 500x500 was the preferred size, a 510x510 image would get picked before a 495x495 one, or vice-versa.
Was about to post this idea myself, but then this one floated to the top. Don't think it's necessary to say that selected art should be within 10%, though- I'm thinking Bliss should choose whatever art is closest to the preferred size, maybe with the option of giving some preference to larger or smaller art so that, if 500x500 was the preferred size, a 510x510 image would get picked before a 495x495 one, or vice-versa.