canvasでわかるようです。
引用元
以下引用
HTMl
1
2 <!DOCTYPE html>
3 <html>
4 <head>
5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
6 <title></title>
7 <meta charset="utf-8" />
8
9 <script type="text/javascript">
10 function draw() {
11 var canvas = document.getElementById('SimpleCanvas');
12
13 if (!canvas || !canvas.getContext) {
14 return false;
15 }
16 var context = canvas.getContext('2d');
17
18 var img = new Image();
19
20 img.onload = function onImageLoad() {
21 context.drawImage(img, 0, 0);
22 var imageData = context.getImageData(64, 64, 1, 1);
23 var outFrame = document.getElementById('output');
24 outFrame.innerText = "(R,G,B,a) = (" + imageData.data[0] + "," + imageData.data[1] + "," + imageData.data[2] + "," + imageData.data[3] + ")";
25 }
26
27 img.src = 'resource/img03.png'; //相対URLの場合
28 //img.src = 'http://www.ipentec.com/demo/canvas/resource/img03.png';
29 }
30 </script>
31
32 </head>
33 <body onload="draw()" style="background-color:#D0D0D0;">
34 <canvas id="SimpleCanvas" width="640" height="360" style="background-color:#FFFFFF;"></canvas>
35 <div>Canvas Demo</div>
36 <div id="output"></div>
37 </body>
38 </html>
39
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退会済みユーザー
2019/11/24 07:46
2019/11/25 01:41