caxinha/src/photoshop/threshold.js

A npm of image manipulation, gif catcher and functions

module.exports = async (image, amount) => {
    if (!image) throw new Error("Parâmetro <image> não definido!");
        const Canvas = require("canvas");
        const img = await Canvas.loadImage(image);
        const canvas = await Canvas.createCanvas(img.width, img.height);
        const ctx = canvas.getContext("2d");
        ctx.drawImage(img, 0, 0);

        const imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);

        for (let i = 0; i < imgData.data.length; i += 4) {
        var r = imgData.data[i];
        var g = imgData.data[i + 1];
        var b = imgData.data[i + 2];
        var v = (0.2126 * r + 0.7152 * g + 0.0722 * b >= amount) ? 255 : 0;
        imgData.data[i] = imgData.data[i + 1] = imgData.data[i + 2] = v
        }

        ctx.putImageData(imgData, 0, 0);

        return canvas.toBuffer();
}