The first version of this command
takes an area of the current canvas and converts it into an image
using a mask colour.
The second version of this command
takes an area of the current canvas and converts it into an image
using another canvas which contains a greyscale mask. The greyscale
mask must be the same width and height as the rest of the image.
x1,y1,x2,y2 specify the area of the current canvas
to copy from. They are the left,top,right,and bottom co-ordinates
respectively.
mask is the colour to use as transparent when the
image is produced. This can be built using Make
Colour.
i is the index of the image that will be produced.
shrink is a boolean value of whether or not to shrink
the image just to it's contents. A value of true means that it
should, a value of false means that it should be left at it's
full size.
bank is the id of the bank to add the image to. If
this is not specified then the current image bank is used.
c is the canvas id to get the greyscale mask from.
mX,mY are the top and left co-ordinates of the grey
scale map in the canvas.