Fix dithering process

zk-phi · Jul 3, 2024 · 31a7dc0 · 31a7dc0
1 parent fdb5a1d
commit 31a7dc0
Showing 1 changed file with 10 additions and 10 deletions.
diff --git a/src/utils/binarize.ts b/src/utils/binarize.ts
@@ -3,14 +3,14 @@
 // This reduces number of colors before quantization, and also
 // offers better result by dithering quantization errors.
 
-const THRESHOLD = 80;
+const THRESHOLD = 128;
 
 export const binarizeTransparency = (
   data: Uint8ClampedArray,
   width: number,
   height: number,
 ): void => {
-  const err: number[] = new Array(width * height);
+  const err: number[] = (new Array(width * height)).fill(0);
   for (let y = 0; y < height; y += 1) {
     if (y % 2 === 0) { // iterate from left to right
       for (let x = 0; x < width; x += 1) {
@@ -30,11 +30,11 @@ export const binarizeTransparency = (
         }
         /* eslint-enable no-param-reassign */
         // Floyd-steinberg dithering
-        if (x + 1 < width) err[y * width + (x + 1)] = newErr * 7 / 16;
+        if (x + 1 < width) err[y * width + (x + 1)] += newErr * 7 / 16;
         if (y + 1 < height) {
-          if (x - 1 >= 0) err[(y + 1) * width + (x - 1)] = newErr * 3 / 16;
-          err[(y + 1) * width + x] = newErr * 5 / 16;
-          if (x + 1 < width) err[(y + 1) * width + (x + 1)] = newErr * 1 / 16;
+          if (x - 1 >= 0) err[(y + 1) * width + (x - 1)] += newErr * 3 / 16;
+          err[(y + 1) * width + x] += newErr * 5 / 16;
+          if (x + 1 < width) err[(y + 1) * width + (x + 1)] += newErr * 1 / 16;
         }
       }
     } else { // iterate from right to left
@@ -55,11 +55,11 @@ export const binarizeTransparency = (
         }
         /* eslint-enable no-param-reassign */
         // Floyd-steinberg dithering
-        if (x - 1 >= 0) err[y * width + (x - 1)] = newErr * 7 / 16;
+        if (x - 1 >= 0) err[y * width + (x - 1)] += newErr * 7 / 16;
         if (y + 1 < height) {
-          if (x + 1 < width) err[(y + 1) * width + (x + 1)] = newErr * 3 / 16;
-          err[(y + 1) * width + x] = newErr * 5 / 16;
-          if (x - 1 >= 0) err[(y + 1) * width + (x - 1)] = newErr * 1 / 16;
+          if (x + 1 < width) err[(y + 1) * width + (x + 1)] += newErr * 3 / 16;
+          err[(y + 1) * width + x] += newErr * 5 / 16;
+          if (x - 1 >= 0) err[(y + 1) * width + (x - 1)] += newErr * 1 / 16;
         }
       }
     }