Computer_Graphics/lab_02_1.html at master · capsidimit/Computer_Graphics · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
<html>
    <body>
        <canvas width="500" , height="281" , id="layer_1"> </canvas>
        <canvas width="500" , height="281" , id="layer_2"> </canvas>

        <script>
            var canvas = document.getElementById("layer_1");
            var ctx = canvas.getContext("2d");

            var canvas2 = document.getElementById("layer_2");
            var ctx2 = canvas2.getContext("2d");

            let img = new Image();
            img.crossOrigin = "anonymus";
            img.src = "https://upload.wikimedia.org/wikipedia/commons/f/f9/Phoenicopterus_ruber_in_S%C3%A3o_Paulo_Zoo.jpg"; //Jerry meme.jpg

            let _average=0;
            let img_data = new ImageData(1,1);
            img.onload = function () {
                ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
                img_data = ctx.getImageData(0, 0, canvas.width, canvas.height);
                console.log(img_data);
                for (var index = 0; index < img_data.data.length; index += 4)
                    {
                        _average = (img_data.data[index] + img_data.data[index+1] + img_data.data[index+2])/3;

                        img_data.data[index] = _average;
                        img_data.data[index + 1] = _average;
                        img_data.data[index + 2] = _average;
                        img_data.data[index + 3] = 255;
                    }
                ctx2.putImageData(img_data, 0, 0, 0, 0, canvas2.width, canvas2.height);
                }

        </script>
    </body>
</html>