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Test that two images are identical for the Seam Carving algorithm. (#694)

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* Test that two images are identical for the Seam Carving algorithm.

* Tune the Seam Carving tests.

* Tune the Seam Carving tests.

* Tune the Seam Carving tests.

* Tune the Seam Carving tests.
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Oleksii Trekhleb 2021-04-21 07:39:58 +02:00 committed by GitHub
parent f0b246a521
commit cfd9a630ff
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2 changed files with 43 additions and 2 deletions
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1
.husky/pre-commit
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@ -1,5 +1,6 @@
#!/bin/sh
. "$(dirname "$0")/_/husky.sh"
# @TODO: Implement the pre-commit checks.
# npm run lint
# npm run test

44
src/algorithms/image-processing/seam-carving/__tests__/resizeImageWidth.test.js
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@ -4,6 +4,40 @@ 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';
/**
* Compares two images and finds the number of different pixels.
*
* @param {ImageData} imgA - ImageData for the first image.
* @param {ImageData} imgB - ImageData for the second image.
* @param {number} threshold - Color difference threshold [0..255]. Smaller - stricter.
* @returns {number} - Number of different pixels.
*/
function pixelsDiff(imgA, imgB, threshold = 0) {
if (imgA.width !== imgB.width || imgA.height !== imgB.height) {
throw new Error('Images must have the same size');
}
let differentPixels = 0;
const numColorParams = 4; // RGBA
for (let pixelIndex = 0; pixelIndex < imgA.data.length; pixelIndex += numColorParams) {
// Get pixel's color for each image.
const [aR, aG, aB] = imgA.data.subarray(pixelIndex, pixelIndex + numColorParams);
const [bR, bG, bB] = imgB.data.subarray(pixelIndex, pixelIndex + numColorParams);
// Get average pixel's color for each image (make them greyscale).
const aAvgColor = Math.floor((aR + aG + aB) / 3);
const bAvgColor = Math.floor((bR + bG + bB) / 3);
// Compare pixel colors.
if (Math.abs(aAvgColor - bAvgColor) > threshold) {
differentPixels += 1;
}
}
return differentPixels;
}
describe('resizeImageWidth', () => {
it('should perform content-aware image width reduction', () => {
// @see: https://jestjs.io/docs/asynchronous
@ -21,6 +55,7 @@ describe('resizeImageWidth', () => {
const canvasAfter = createCanvas(imgAfter.width, imgAfter.height);
const ctxAfter = canvasAfter.getContext('2d');
ctxAfter.drawImage(imgAfter, 0, 0, imgAfter.width, imgAfter.height);
const imgDataAfter = ctxAfter.getImageData(0, 0, imgAfter.width, imgAfter.height);
const toWidth = Math.floor(imgBefore.width / 2);
@ -44,8 +79,13 @@ describe('resizeImageWidth', () => {
expect(imgDataTest.width).toBe(imgAfter.width);
expect(imgDataTest.height).toBe(imgAfter.height);
// @TODO: Check that images are identical.
// expect(canvasTest.toDataURL()).toEqual(canvasAfter.toDataURL());
const colorThreshold = 50;
const differentPixels = pixelsDiff(imgDataTest, imgDataAfter, colorThreshold);
// Allow 10% of pixels to be different
const pixelsThreshold = Math.floor((imgAfter.width * imgAfter.height) / 10);
expect(differentPixels).toBeLessThanOrEqual(pixelsThreshold);
});
});
});