Added autoLevel to MagickImage.

src/magick-image.ts

@@ -340,6 +340,19 @@ export interface IMagickImage extends IDisposable {
      */
     autoGamma(channels: Channels): void;
 
+    /**
+     * Adjusts the levels of a particular image channel by scaling the minimum and maximum
+     * values to the full quantum range.
+     */
+    autoLevel(): void;
+
+    /**
+     * Adjusts the levels of a particular image channel by scaling the minimum and maximum
+     * values to the full quantum range.
+     * @param channels - The channel(s) to level.
+     */
+    autoLevel(channels: Channels): void;
+
     /**
      * Adjusts an image so that its orientation is suitable for viewing.
      */
@@ -1937,6 +1950,14 @@ export class MagickImage extends NativeInstance implements IMagickImage {
         });
     }
 
+    autoLevel(): void;
+    autoLevel(channelsOrUndefined?: Channels): void {
+        this.useExceptionPointer(exception => {
+            const channels = this.valueOrDefault(channelsOrUndefined, Channels.Undefined);
+            ImageMagick._api._MagickImage_AutoLevel(this._instance, channels, exception);
+        });
+    }
+
     autoOrient(): void {
         this.useException(exception => {
             const instance = ImageMagick._api._MagickImage_AutoOrient(this._instance, exception.ptr);

tests/magick-image/auto-level.spec.ts

@@ -0,0 +1,36 @@
+// Copyright Dirk Lemstra https://github.com/dlemstra/magick-wasm.
+// Licensed under the Apache License, Version 2.0.
+
+import { Channels } from '@src/enums/channels';
+import { ErrorMetric } from '@src/enums/error-metric';
+import { TestImages } from '@test/test-images';
+
+describe('MagickImage#autoLevel', () => {
+    it('should auto level to the image', () => {
+        TestImages.Builtin.rose.use(image => {
+            image.autoLevel();
+
+            expect(image).toHavePixelWithColor(5, 40, '#5b5646ff');
+        });
+    });
+
+    it('should only auto level the specified channels', () => {
+        TestImages.Builtin.rose.use(image => {
+            image.autoLevel(Channels.Red);
+
+            expect(image).toHavePixelWithColor(5, 40, '#516556ff');
+        });
+    });
+
+    it('should use the correct default channels', () => {
+        TestImages.Builtin.rose.use(imageA => {
+            imageA.clone(imageB => {
+                imageA.autoLevel();
+                imageB.autoLevel(Channels.Undefined);
+
+                const distortion = imageA.compare(imageB, ErrorMetric.RootMeanSquared);
+                expect(distortion).toBe(0);
+            })
+        });
+    });
+});