[orx-fx] Add Duotone, DuotoneGradient, LumaHalftone, Posterize, RgbToOkLab, OkLabToRgb

orx-fx/src/demo/kotlin/DemoOkLab01.kt

@@ -0,0 +1,27 @@
+import org.openrndr.extra.fx.color.RgbToOkLab
+import org.openrndr.extra.fx.color.OkLabToRgb
+import org.openrndr.application
+import org.openrndr.draw.ColorType
+import org.openrndr.draw.createEquivalent
+import org.openrndr.draw.loadImage
+
+/**
+ * This demonstrates converting a [ColorBuffer] from and to (OK)LAB color space using the [RgbToOkLab] and [OkLabToRgb]
+ * filters. The (OK)Lab representation is signed and requires a floating point representation.
+ */
+
+fun main() {
+    application {
+        program {
+            val rgbToOkLab = RgbToOkLab()
+            val okLabToRgb = OkLabToRgb()
+            val image = loadImage("demo-data/images/image-001.png")
+            val labImage = image.createEquivalent(type = ColorType.FLOAT32)
+            rgbToOkLab.apply(image, labImage)
+            okLabToRgb.apply(labImage, image)
+            extend {
+                drawer.image(image)
+            }
+        }
+    }
+}