add histogram module (#354)

* add histogram module Signed-off-by: tech4GT <varun.gupta1798@gmail.com> * add option to drop gradient Signed-off-by: Varun Gupta <varun.gupta1798@gmail.com> * fix bug Signed-off-by: Varun Gupta <varun.gupta1798@gmail.com>
2025-12-13 20:00:05 +01:00 · 2018-10-09 01:26:35 +05:30
parent 1d085c7f20
commit 276a637ac3
6 changed files with 268 additions and 38 deletions
--- a/src/modules/Histogram/Module.js
+++ b/src/modules/Histogram/Module.js
@@ -0,0 +1,93 @@
+/*
+ * Calculates the histogram of the image
+ */
+module.exports = function Channel(options, UI) {
+
+    var output;
+
+    function draw(input, callback, progressObj) {
+
+        options.gradient = options.gradient || "true";
+        options.gradient = JSON.parse(options.gradient);
+
+        progressObj.stop(true);
+        progressObj.overrideFlag = true;
+
+        var step = this, hist = new Array(256).fill(0);
+
+        function changePixel(r, g, b, a) {
+            let pixVal = Math.round((r + g + b) / 3);
+            hist[pixVal]++;
+            return [r, g, b, a];
+        }
+
+        function extraManipulation(pixels) {
+            // if (!options.inBrowser)
+            //     require('fs').writeFileSync('./output/histo.txt', hist.reduce((tot, cur, idx) => `${tot}\n${idx} : ${cur}`, ``));
+            var newarray = new Uint8Array(4 * 256 * 256);
+            pixels.data = newarray;
+            pixels.shape = [256, 256, 4];
+            pixels.stride[1] = 4 * 256;
+
+            for (let x = 0; x < 256; x++) {
+                for (let y = 0; y < 256; y++) {
+                    pixels.set(x, y, 0, 255);
+                    pixels.set(x, y, 1, 255);
+                    pixels.set(x, y, 2, 255);
+                    pixels.set(x, y, 3, 255);
+                }
+            }
+
+            let startY = options.gradient ? 10 : 0;
+            if (options.gradient) {
+                for (let x = 0; x < 256; x++) {
+                    for (let y = 0; y < 10; y++) {
+                        pixels.set(x, 255 - y, 0, x);
+                        pixels.set(x, 255 - y, 1, x);
+                        pixels.set(x, 255 - y, 2, x);
+                    }
+                }
+            }
+
+            let convfactor = (256 - startY) / Math.max(...hist);
+
+            for (let x = 0; x < 256; x++) {
+                let pixCount = Math.round(convfactor * hist[x]);
+
+                for (let y = startY; y < pixCount; y++) {
+                    pixels.set(x, 255 - y, 0, 204);
+                    pixels.set(x, 255 - y, 1, 255);
+                    pixels.set(x, 255 - y, 2, 153);
+                }
+            }
+
+            return pixels;
+        }
+
+        function output(image, datauri, mimetype) {
+
+            // This output is accesible by Image Sequencer
+            step.output = { src: datauri, format: mimetype };
+
+        }
+
+        return require('../_nomodule/PixelManipulation.js')(input, {
+            output: output,
+            changePixel: changePixel,
+            extraManipulation: extraManipulation,
+            format: input.format,
+            image: options.image,
+            inBrowser: options.inBrowser,
+            callback: callback
+        });
+
+    }
+
+    return {
+        options: options,
+        //setup: setup, // optional
+        draw: draw,
+        output: output,
+        UI: UI
+    }
+}