Adding a Seam Carving algorithm with Dynamic Programming implementation. (trekhleb#693)

* Adding a Seam Carving algorithm with Dynamic Programming implementation. * Adding a Seam Carving algorithm with Dynamic Programming implementation. * Adding a Seam Carving algorithm with Dynamic Programming implementation. * Testing Husky integration. * Testing Husky integration.

Author: trekhleb

.husky/.gitignore

@@ -0,0 +1 @@
+_

.husky/pre-commit

@@ -0,0 +1,5 @@
+#!/bin/sh
+. "$(dirname "$0")/_/husky.sh"
+
+# npm run lint
+# npm run test

.huskyrc.json

@@ -152,6 +152,8 @@ a set of rules that precisely define a sequence of operations.
  * `B` [NanoNeuron](https://github.com/trekhleb/nano-neuron) - 7 simple JS functions that illustrate how machines can actually learn (forward/backward propagation)
  * `B` [k-NN](src/algorithms/ml/knn) - k-nearest neighbors classification algorithm
  * `B` [k-Means](src/algorithms/ml/k-means) - k-Means clustering algorithm
+* **Image Processing**
+ * `B` [Seam Carving](src/algorithms/image-processing/seam-carving) - content-aware image resizing algorithm
 * **Uncategorized**
  * `B` [Tower of Hanoi](src/algorithms/uncategorized/hanoi-tower)
  * `B` [Square Matrix Rotation](src/algorithms/uncategorized/square-matrix-rotation) - in-place algorithm
@@ -203,6 +205,7 @@ algorithm is an abstraction higher than a computer program.
  * `B` [Unique Paths](src/algorithms/uncategorized/unique-paths)
  * `B` [Rain Terraces](src/algorithms/uncategorized/rain-terraces) - trapping rain water problem
  * `B` [Recursive Staircase](src/algorithms/uncategorized/recursive-staircase) - count the number of ways to reach to the top
+ * `B` [Seam Carving](src/algorithms/image-processing/seam-carving) - content-aware image resizing algorithm
  * `A` [Levenshtein Distance](src/algorithms/string/levenshtein-distance) - minimum edit distance between two sequences
  * `A` [Longest Common Subsequence](src/algorithms/sets/longest-common-subsequence) (LCS)
  * `A` [Longest Common Substring](src/algorithms/string/longest-common-substring)

README.md

@@ -7,7 +7,8 @@
  "lint": "eslint ./src/**",
  "test": "jest",
  "coverage": "npm run test -- --coverage",
- "ci": "npm run lint && npm run coverage"
+ "ci": "npm run lint && npm run coverage",
+ "prepare": "husky install"
  },
  "repository": {
  "type": "git",
@@ -37,13 +38,14 @@
  "@babel/cli": "7.12.10",
  "@babel/preset-env": "7.12.11",
  "@types/jest": "26.0.19",
+ "canvas": "^2.7.0",
  "eslint": "7.16.0",
  "eslint-config-airbnb": "18.2.1",
  "eslint-plugin-import": "2.22.1",
  "eslint-plugin-jest": "24.1.3",
  "eslint-plugin-jsx-a11y": "6.4.1",
  "eslint-plugin-react": "7.21.5",
- "husky": "4.3.6",
+ "husky": "6.0.0",
  "jest": "26.6.3"
  },
  "dependencies": {}

package-lock.json

@@ -0,0 +1,51 @@
+import { createCanvas, loadImage } from 'canvas';
+import resizeImageWidth from '../resizeImageWidth';
+
+const testImageBeforePath = './src/algorithms/image-processing/seam-carving/__tests__/test-image-before.jpg';
+const testImageAfterPath = './src/algorithms/image-processing/seam-carving/__tests__/test-image-after.jpg';
+
+describe('resizeImageWidth', () => {
+ it('should perform content-aware image width reduction', () => {
+ // @see: https://jestjs.io/docs/asynchronous
+ return Promise.all([
+ loadImage(testImageBeforePath),
+ loadImage(testImageAfterPath),
+ ]).then(([imgBefore, imgAfter]) => {
+ // Original image.
+ const canvasBefore = createCanvas(imgBefore.width, imgBefore.height);
+ const ctxBefore = canvasBefore.getContext('2d');
+ ctxBefore.drawImage(imgBefore, 0, 0, imgBefore.width, imgBefore.height);
+ const imgDataBefore = ctxBefore.getImageData(0, 0, imgBefore.width, imgBefore.height);
+
+ // Resized image saved.
+ const canvasAfter = createCanvas(imgAfter.width, imgAfter.height);
+ const ctxAfter = canvasAfter.getContext('2d');
+ ctxAfter.drawImage(imgAfter, 0, 0, imgAfter.width, imgAfter.height);
+
+ const toWidth = Math.floor(imgBefore.width / 2);
+
+ const {
+ img: resizedImg,
+ size: resizedSize,
+ } = resizeImageWidth({ img: imgDataBefore, toWidth });
+
+ expect(resizedImg).toBeDefined();
+ expect(resizedSize).toBeDefined();
+
+ // Resized image generated.
+ const canvasTest = createCanvas(resizedSize.w, resizedSize.h);
+ const ctxTest = canvasTest.getContext('2d');
+ ctxTest.putImageData(resizedImg, 0, 0, 0, 0, resizedSize.w, resizedSize.h);
+ const imgDataTest = ctxTest.getImageData(0, 0, resizedSize.w, resizedSize.h);
+
+ expect(resizedSize).toEqual({ w: toWidth, h: imgBefore.height });
+ expect(imgDataTest.width).toBe(toWidth);
+ expect(imgDataTest.height).toBe(imgBefore.height);
+ expect(imgDataTest.width).toBe(imgAfter.width);
+ expect(imgDataTest.height).toBe(imgAfter.height);
+
+ // @TODO: Check that images are identical.
+ // expect(canvasTest.toDataURL()).toEqual(canvasAfter.toDataURL());
+ });
+ });
+});