Import L1 (celery) as l1/

l1/sexp_effects/effects/outline.sexp

@@ -0,0 +1,24 @@
+;; Outline effect - shows only edges
+(require-primitives "image")
+
+(define-effect outline
+  :params (
+    (thickness :type int :default 2 :range [1 10])
+    (threshold :type int :default 100 :range [20 300])
+    (color :type list :default (list 0 0 0))
+    (fill_mode :type string :default "original")
+  )
+  (let* ((edge-img (image:edge-detect frame (/ threshold 2) threshold))
+         (dilated (if (> thickness 1)
+                      (dilate edge-img thickness)
+                      edge-img))
+         (base (cond
+                 ((= fill_mode "original") (copy frame))
+                 ((= fill_mode "white") (make-image (image:width frame) (image:height frame) (list 255 255 255)))
+                 (else (make-image (image:width frame) (image:height frame) (list 0 0 0))))))
+    (map-pixels base
+      (lambda (x y c)
+        (let ((edge-val (luminance (pixel dilated x y))))
+          (if (> edge-val 128)
+              color
+              c))))))