konva/lib/filters/Solarize.js

HTML5 2d canvas library for interactive graphics, design editors, whiteboards, and diagrams.

/**
 * Solarize Filter
 * @function
 * @name Solarize
 * @memberof Konva.Filters
 * @param {Object} imageData
 * @example
 * node.cache();
 * node.filters([Konva.Filters.Solarize]);
 */
export const Solarize = function (imageData) {
    const threshold = 128;
    const d = imageData.data;
    for (let i = 0; i < d.length; i += 4) {
        const r = d[i], g = d[i + 1], b = d[i + 2];
        // sRGB luma
        const L = 0.2126 * r + 0.7152 * g + 0.0722 * b;
        if (L >= threshold) {
            d[i] = 255 - r;
            d[i + 1] = 255 - g;
            d[i + 2] = 255 - b;
        }
    }
    return imageData;
};