Don't know if it's possible, surely more helpful for Fill image then Fit Image (useless for stretch).
But for example if I have a portrait image of a person and I want to crop-resize it, it's more useful to have the top part because that's where the head is.
Could perhaps also be added to Crop Image (or only to Crop Image). I think this could already be done by calculating the image height and divide the height and crop it, but a simple Anchor could be so simple.
So for example if I would resize a portait image to square and use "Fill Image" I could set the anchor to middle top and get the head of the portrait centered rather then the body ?