node-image-filter/lib/renderer/preset.js

Image Filter Library for nodejs

const convolution = require('./convolution');
const utility = require('../utility');

module.exports = {
    none: function (pixels) {
        return pixels.data;
    },

    invert: function (pixels) {
        var data = pixels.data;
        for (var i = 0; i < data.length; i += 4) {
            data[i] = utility.validatePixelValue(255 - data[i]);
            data[i + 1] = utility.validatePixelValue(255 - data[i + 1]);
            data[i + 2] = utility.validatePixelValue(255 - data[i + 2]);
            data[i + 3] = utility.validatePixelValue(255);
        }
        return data;
    },

    grayscale: function (pixels) {
        var data = pixels.data;
        for (var i = 0; i < data.length; i += 4) {
            var r = data[i];
            var g = data[i + 1];
            var b = data[i + 2];

            var v = 0.2126 * r + 0.7152 * g + 0.0722 * b;
            data[i] = data[i + 1] = data[i + 2] = v
        }
        return data;
    },

    sepia: function (pixels) {
        var data = pixels.data;
        for (var i = 0; i < data.length; i += 4) {
            var r = data[i];
            var g = data[i + 1];
            var b = data[i + 2];

            data[i] = r * 0.3588 + g * 0.7044 + b * 0.1368;
            data[i + 1] = r * 0.2990 + g * 0.5870 + b * 0.1140;
            data[i + 2] = r * 0.2392 + g * 0.4696 + b * 0.0912;
        }
        return data;
    },

    brightness: function (pixels, options) {
        var data = pixels.data;
        var value = options.value || 5;
        for (var i = 0; i < data.length; i += 4) {
            data[i] = utility.validatePixelValue(data[i] + value);
            data[i + 1] = utility.validatePixelValue(data[i + 1] + value);
            data[i + 2] = utility.validatePixelValue(data[i + 2] + value);
        }
        return data;
    },

    sobel: function (pixels) {
        return convolution(pixels,
               [-1, 0, 1,
                -2, 0, 2,
                -1, 0, 1], 1);
    },

    sharpen: function (pixels) {
        return convolution(pixels,
               [-1, -1, -1,
                -1,  8, -1,
                -1, -1, -1], 1);
    },

    blur: function (pixels, options) {
        var value = options.value || 50;
        var offset = 1 / (value / 10);
        return convolution(pixels,
               [offset, offset, offset,
                offset, offset, offset,
                offset, offset, offset], 1);
    }
};