The size portion indicates the width and height of the frame. If no offsets are given then the border added is a solid color. Offsets x and y, if present, specify that the width and height of the border is partitioned to form an outer bevel of thickness x pixels and an inner bevel of thickness y pixels. Negative offsets make no sense as frame arguments.
Specifies the geometry specification for frame to place around thumbnail. If this parameter is not specified, then the montage is unframed.