thedesk/app/node_modules/@jimp/plugin-normalize/es/index.js

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2019-09-13 00:38:13 +10:00
/* eslint-disable no-labels */
import { isNodePattern } from '@jimp/utils';
/**
* Get an image's histogram
* @return {object} An object with an array of color occurrence counts for each channel (r,g,b)
*/
function histogram() {
var histogram = {
r: new Array(256).fill(0),
g: new Array(256).fill(0),
b: new Array(256).fill(0)
};
this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function (x, y, index) {
histogram.r[this.bitmap.data[index + 0]]++;
histogram.g[this.bitmap.data[index + 1]]++;
histogram.b[this.bitmap.data[index + 2]]++;
});
return histogram;
}
/**
* Normalize values
* @param {integer} value Pixel channel value.
* @param {integer} min Minimum value for channel
* @param {integer} max Maximum value for channel
* @return {integer} normalized values
*/
var _normalize = function normalize(value, min, max) {
return (value - min) * 255 / (max - min);
};
var getBounds = function getBounds(histogramChannel) {
return [histogramChannel.findIndex(function (value) {
return value > 0;
}), 255 - histogramChannel.slice().reverse().findIndex(function (value) {
return value > 0;
})];
};
/**
* Normalizes the image
* @param {function(Error, Jimp)} cb (optional) a callback for when complete
* @returns {Jimp} this for chaining of methods
*/
export default (function () {
return {
normalize: function normalize(cb) {
var h = histogram.call(this); // store bounds (minimum and maximum values)
var bounds = {
r: getBounds(h.r),
g: getBounds(h.g),
b: getBounds(h.b)
}; // apply value transformations
this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function (x, y, idx) {
var r = this.bitmap.data[idx + 0];
var g = this.bitmap.data[idx + 1];
var b = this.bitmap.data[idx + 2];
this.bitmap.data[idx + 0] = _normalize(r, bounds.r[0], bounds.r[1]);
this.bitmap.data[idx + 1] = _normalize(g, bounds.g[0], bounds.g[1]);
this.bitmap.data[idx + 2] = _normalize(b, bounds.b[0], bounds.b[1]);
});
if (isNodePattern(cb)) {
cb.call(this, null, this);
}
return this;
}
};
});
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