.., a quick way of exploring blend-modes if you cant remember their names (define blend-modes #("zero" "one" "dst-color" "one-minus-dst-color" "src-alpha" "one-minus-src-alpha" "dst-alpha" "one-minus-dst-alpha" "src-alpha-saturate")) (define (blend src dest) (blend-mode (vector-ref blend-modes src) (vector-ref blend-modes dest))) then a function like (blend 3 1) should work