;; Emboss effect - creates raised/3D appearance
;; @param strength float [0.5, 3] default 1
;; @param blend float [0, 1] default 0.3

(define-effect emboss
  ((strength 1) (blend 0.3))
  (let* ((kernel (list (list (- strength) (- strength) 0)
                       (list (- strength) 1 strength)
                       (list 0 strength strength)))
         (embossed (convolve frame kernel)))
    (blend-images embossed frame blend)))