[racket] monochrome bitmaps

A "monochrome" bitmap is just black-and-white. If a grayscale PNG has
more colors than black or white, it will be loaded the same way as a
color bitmap.

At Fri, 2 Nov 2012 22:15:39 -0400, Harry Spier wrote:
> To clarify one point:
> Is a monochrome bitmap a greyscale bitmap or a black and white bitmap?
> I see from the documentation that the form (make-object bitmap% bits
> width height) produces a black and white bitmap but for the form I
> asked about (shown again below) subject to the restriction Matthew
> described (i.e. png or xbm file format) will that produce a greyscale
> bitmap or a strictly black and white bitmap?
> 
>        (make-object bitmap%
>            in ;path to greyscale image files
>         [ kind
>           bg-color
>         complain-on-failure?])
> 
> Thanks,
> Harry Spier