It could be a nice feature if you could set 'max width' AND 'max height' in the autoscale fields. (some product pictures are either very wide or very high)
Then the picture don't have to be cropped(as now if you fill out both width and height), but resamples in the right proportions instead.
Now if you fill out both width and height the image editor crops the picture, you offen don't want your product picture cropped.
A sharpen feauture could also be very useful.
Standard you can set 3 sizes for pictures: small, medium and large. Why don't you led the user decise how many picture sizes you want? (so you backend can make all the sizes you want) Sometimes you can use/need more than 3 picture sizes.