I'm not 100% positive, but probably 90% sure that the answer is no. If I remember what I read correctly earlier, that would require resampling the cover, which would degrade performance or something. You could put up a feature request for, say, LMS to build a cover cache with resampled images generated as media gets scanned, instead of on the fly, which might work, but I'm not sure. I really can barely keep my eyes open at this point though, so good luck.