Support for sino regions

Now one can read the height of images and downsample images separately which will be important elsewhere.
However, the image height parameter is on the edge and will get very annoying for users when they use reruns because of what we concluded (the parameter is put to zero after each grpah run, so one reads zeros all the time). On the other hand, this is something which can be fixed for rerun-enabled graphs later I guess. I don't know. What does @matze think?