Painting a gray or colored wash over a display.

Specify a translucent design as the ink, such as :ink (compose-in +black+ (make-opacity 0.25)), :ink (compose-in +red+ (make-opacity 0.1)), or :ink (compose-in +foreground-ink+ (make-opacity 0.75)). The last example can be abbreviated as :ink (make-opacity 0.75). On a non-color, non-grayscale display this will usually turn into a stipple.

Drawing a faded but opaque version of the foreground color.

Specify :ink (compose-over (compose-in +foreground-ink+ (make-opacity 0.25)) +background-ink+) to draw at 25% of the normal contrast. On a non-color, non-grayscale display this will probably turn into a stipple.

Drawing a tiled pattern.

Specify :ink (make-rectangular-tile (make-pattern array colors)).

Drawing a "bitmap".

Use (draw-design medium (make-pattern bit-array (list +background-ink+ +foreground-ink+)) :transformation (make-translation-transformation x y)).