76 lines
2.2 KiB
JavaScript
76 lines
2.2 KiB
JavaScript
/* eslint-disable no-labels */
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import { isNodePattern } from '@jimp/utils';
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/**
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* Get an image's histogram
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* @return {object} An object with an array of color occurrence counts for each channel (r,g,b)
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*/
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function histogram() {
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var histogram = {
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r: new Array(256).fill(0),
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g: new Array(256).fill(0),
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b: new Array(256).fill(0)
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};
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this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function (x, y, index) {
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histogram.r[this.bitmap.data[index + 0]]++;
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histogram.g[this.bitmap.data[index + 1]]++;
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histogram.b[this.bitmap.data[index + 2]]++;
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});
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return histogram;
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}
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/**
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* Normalize values
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* @param {integer} value Pixel channel value.
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* @param {integer} min Minimum value for channel
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* @param {integer} max Maximum value for channel
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* @return {integer} normalized values
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*/
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var _normalize = function normalize(value, min, max) {
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return (value - min) * 255 / (max - min);
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};
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var getBounds = function getBounds(histogramChannel) {
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return [histogramChannel.findIndex(function (value) {
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return value > 0;
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}), 255 - histogramChannel.slice().reverse().findIndex(function (value) {
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return value > 0;
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})];
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};
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/**
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* Normalizes the image
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* @param {function(Error, Jimp)} cb (optional) a callback for when complete
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* @returns {Jimp} this for chaining of methods
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*/
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export default (function () {
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return {
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normalize: function normalize(cb) {
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var h = histogram.call(this); // store bounds (minimum and maximum values)
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var bounds = {
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r: getBounds(h.r),
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g: getBounds(h.g),
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b: getBounds(h.b)
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}; // apply value transformations
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this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function (x, y, idx) {
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var r = this.bitmap.data[idx + 0];
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var g = this.bitmap.data[idx + 1];
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var b = this.bitmap.data[idx + 2];
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this.bitmap.data[idx + 0] = _normalize(r, bounds.r[0], bounds.r[1]);
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this.bitmap.data[idx + 1] = _normalize(g, bounds.g[0], bounds.g[1]);
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this.bitmap.data[idx + 2] = _normalize(b, bounds.b[0], bounds.b[1]);
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});
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if (isNodePattern(cb)) {
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cb.call(this, null, this);
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}
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return this;
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}
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};
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});
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//# sourceMappingURL=index.js.map
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