fix: move important line to histogram

Author: opatiny

src/compute/__tests__/histogram.test.ts

@@ -36,6 +36,23 @@ test('binary image', () => {
   expect(histogram[255]).toBe(9);
 });
 
+test('grey 16-bit image', () => {
+  const image = createImageFromData(
+    [
+      [0, 0, 0, 0, 0],
+      [0, 40000, 255, 255, 0],
+      [0, 255, 255, 255, 0],
+      [0, 255, 255, 255, 0],
+      [0, 0, 0, 0, 0],
+    ],
+    'GREY',
+    { bitDepth: 16 },
+  );
+  const histogram = image.histogram();
+
+  expect(histogram.length).toBe(2 ** 16);
+});
+
 test('grey 16-bit image with 2 slots', () => {
   const image = createImageFromData(
     [

src/compute/histogram.ts

@@ -11,7 +11,7 @@ export interface HistogramOptions {
   channel?: number;
   /**
    * The number of slots that histogram can have.
-   * @default `256`
+   * @default 2 ** image.bitDepth
    */
   slots?: number;
 }
@@ -27,7 +27,7 @@ export function histogram(
   options: HistogramOptions = {},
 ): Uint32Array {
   let { channel } = options;
-  const { slots = 256 } = options;
+  const { slots = 2 ** image.bitDepth } = options;
   if (!(slots !== 0 && (slots & (slots - 1)) === 0)) {
     throw new RangeError(
       'slots must be a power of 2, for example: 64, 256, 1024',

src/operations/threshold.ts

@@ -81,7 +81,7 @@ export function computeThreshold(
       'threshold can only be computed on images with one channel',
     );
   }
-  const histogram = image.histogram({slots: 2**image.bitDepth});
+  const histogram = image.histogram();
 
   switch (algorithm) {
     case 'huang':