feat: expose image.minMax

Refs: #307

Author: opatiny

src/Image.ts

@@ -88,6 +88,7 @@ import {
 } from './operations';
 import { cropAlpha, CropAlphaOptions } from './operations/cropAlpha';
 import { ImageColorModel, colorModels } from './utils/constants/colorModels';
+import { getMinMax } from './utils/getMinMax';
 import { validateChannel, validateValue } from './utils/validators';
 
 import {
@@ -447,6 +448,15 @@ export class Image {
     this.setValue(point.column, point.row, channel, value);
   }
 
+  /**
+   * Find the min and max values of each channel of the image.
+   *
+   * @returns An object with arrays of the min and max values.
+   */
+  public minMax(): { min: number[]; max: number[] } {
+    return getMinMax(this);
+  }
+
   /**
    * Return the raw image data.
    *

src/utils/__tests__/getMinMax.test.ts

@@ -35,3 +35,15 @@ test('rgba image', () => {
     max: [4, 9, 7, 7],
   });
 });
+
+test('image.minMax', () => {
+  const image = testUtils.createRgbaImage([
+    [1, 2, 3, 8],
+    [5, 1, 0, 5],
+    [7, 9, 2, 7],
+  ]);
+  expect(image.minMax()).toStrictEqual({
+    min: [1, 1, 0, 5],
+    max: [7, 9, 3, 8],
+  });
+});

src/utils/getMinMax.ts

@@ -1,12 +1,12 @@
-import { Image } from '../Image';
+import { Image } from '..';
 
 /**
  * Find the min and max values of each channel of the image.
  *
  * @param image - Image to process.
  * @returns An object with arrays of the min and max values.
  */
-export function getMinMax(image: Image) {
+export function getMinMax(image: Image): { min: number[]; max: number[] } {
   const min = new Array(image.channels).fill(image.maxValue);
   const max = new Array(image.channels).fill(0);