Created
November 14, 2017 10:52
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JS图像二值化
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title></title> | |
| </head> | |
| <body> | |
| <canvas id="canvas" onclick="showInfo()"></canvas> | |
| <img id="img" src="1.jpg" width="300" height="200" hidden> | |
| <script> | |
| window.onload = function() { | |
| var canvas = document.getElementById('canvas'); | |
| var img = document.getElementById('img'); | |
| var c = canvas.getContext('2d'); | |
| canvas.width = img.width; | |
| canvas.height = img.height; | |
| c.drawImage(img, 0, 0, canvas.width, canvas.height); | |
| this.showInfo = function() { | |
| var imgData = c.getImageData(0, 0, canvas.width, canvas.height); | |
| var index = 255/2;//阈值 | |
| for (var i = 0; i < imgData.data.length; i += 4) { | |
| var R = imgData.data[i]; //R(0-255) | |
| var G = imgData.data[i + 1]; //G(0-255) | |
| var B = imgData.data[i + 2]; //B(0-255) | |
| var Alpha = imgData.data[i + 3]; //Alpha(0-255) | |
| var sum = (R + G + B) / 3; | |
| if (sum > index) { | |
| imgData.data[i] = 255; | |
| imgData.data[i + 1] = 255; | |
| imgData.data[i + 2] = 255; | |
| imgData.data[i + 3] = Alpha; | |
| } else { | |
| imgData.data[i] = 0; | |
| imgData.data[i + 1] = 0; | |
| imgData.data[i + 2] = 0; | |
| imgData.data[i + 3] = Alpha; | |
| } | |
| } | |
| c.putImageData(imgData, 0, 0); | |
| } | |
| } | |
| </script> | |
| </body> | |
| </html> |
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