gimage(img, drect, prect) places an image on a location in the graph specified by both data coordinates and image coordinates.
drect and prect each contain (xleft, ytop, width, height).
For example:
gimage(img, [5, 5, 0, 0], [0, 0, 36, 72])
creates an image of 0.5x1" at data location (5,5).
gimage may also be used to create an image with explicitly square pixels. To do that, specify h_data=0 and h_paper=0 to let w_data and/or w_paper define the image size, or specify w_data=0 and w_paper=0 to let h_data and/or h_paper define the image size.
Specify aspect>1 to make the pixels taller or aspect<1 to make them wider.
If height is automatic, then the image descends from the given point, unless anchor>0, in which case it is lifted by the given fraction of image height. Similarly, if width is automatic, the image extends to the right of the given point, unless anchor>0, in which case it is shifted to the left by the given fraction.