wip: fix: resize with interpolationType nearest

Closes: #452

Author: tpoisseau

Diff for: src/geometry/__tests__/resize.test.ts

@@ -1,14 +1,24 @@
-import { encodePng } from '../../save';
+import * as path from 'node:path';
 
-test.skip('compare result of resize with opencv (nearest)', () => {
+import { encodePng, write } from '../../save';
+
+test('compare result of resize with opencv (nearest)', async () => {
   const img = testUtils.load('opencv/test.png');
+  const expectedImg = testUtils.load('opencv/testResizeNearest.png');
 
   const resized = img.resize({
     xFactor: 10,
     yFactor: 10,
     interpolationType: 'nearest',
   });
 
+  const substraction = expectedImg.clone().subtract(resized);
+  await write(
+    path.join(__dirname, 'resize_nearest_substraction.png'),
+    substraction,
+  );
+  await write(path.join(__dirname, 'resize_nearest.png'), resized);
+
   expect(resized).toMatchImage('opencv/testResizeNearest.png');
 });
 

Diff for: src/geometry/resize.ts

@@ -58,17 +58,21 @@ export function resize(image: Image, options: ResizeOptions): Image {
     borderType = 'constant',
     borderValue = 0,
   } = options;
-  const { width, height } = checkOptions(image, options);
+  const { width, height, xFactor, yFactor } = checkOptions(image, options);
   const newImage = Image.createFrom(image, { width, height });
   const interpolate = getInterpolationFunction(interpolationType);
   const interpolateBorder = getBorderInterpolation(borderType, borderValue);
   const clamp = getClamp(newImage);
-  const intervalX = (image.width - 1) / (width - 1);
-  const intervalY = (image.height - 1) / (height - 1);
+  const wRatio = 1 / xFactor;
+  const hRatio = 1 / yFactor;
+  // const intervalX = (image.width - 1) / (width - 1);
+  // const intervalY = (image.height - 1) / (height - 1);
   for (let row = 0; row < newImage.height; row++) {
     for (let column = 0; column < newImage.width; column++) {
-      const nx = column * intervalX;
-      const ny = row * intervalY;
+      const nx = (column + 0.5) * wRatio;
+      const ny = (row + 0.5) * hRatio;
+      // const nx = column / xFactor;
+      // const ny = row / yFactor;
       for (let channel = 0; channel < newImage.channels; channel++) {
         const newValue = interpolate(
           image,

Diff for: src/utils/interpolatePixel.ts

@@ -61,8 +61,8 @@ function interpolateNearest(
   channel: number,
   interpolateBorder: BorderInterpolationFunction,
 ): number {
-  column = Math.round(column);
-  row = Math.round(row);
+  column = Math.floor(column);
+  row = Math.floor(row);
 
   return interpolateBorder(column, row, channel, image);
 }