If only one number is given, it is applied to both directions. Note that the numbers given apply to the raw data, not to the eventually enlarged or binned image. If vertical is omitted, it it set to horizontal . The data is centered within the resulting image. This option is still experimental.
Optional arguments are probably subject to future changes.
This color must be an integer between 0 and 100 and is specific to the selected color map. The contour algorithm is pretty fast and does not spline when enlarging the image. If quality is omitted, an appropriate default quality is used. If an optional string is given it is printed instead of the filename. All four forms can be used together with different strings.