Created
April 23, 2020 08:44
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memanipulasi image digital via javascript
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| <!DOCTYPE HTML> | |
| <html> | |
| <head> | |
| </head> | |
| <body> | |
| <canvas id='c' width='600' height='375'></canvas> | |
| <script> | |
| var canvas = document.querySelector('#c'); | |
| var ctx = canvas.getContext('2d'); | |
| var img = new Image(); | |
| img.crossOrigin = ""; | |
| img.src = 'somi.jpg'; | |
| var imgData; | |
| img.onload = function(){ | |
| console.log('image loaded'); | |
| ctx.drawImage(img, 0, 0); | |
| imgData = ctx.getImageData(0, 0, canvas.width, canvas.height); | |
| transformsInGrayScale(); | |
| } | |
| function transformsInGrayScale(){ | |
| //retrieve the pixels | |
| //each pixel has 4 components (red, green, blue, alpha) so: | |
| var numPixels = imgData.data.length / 4; | |
| for(var i = 0; i < numPixels; i++){ | |
| //one pixel = [red (index 0), green (index 1), blue (index 2), alpha (index 3)] | |
| //gets the data (rgbA) from a pixel | |
| var red = imgData.data[i * 4 + 0];//red (index 0) | |
| var green = imgData.data[i * 4 + 1];//green (index 1) | |
| var blue = imgData.data[i * 4 + 2];//blue (index 2) | |
| var alpha = imgData.data[i * 4 + 3];//alpha (index 3) | |
| //transforms in gray | |
| //var gray = (0.3 * red) + (0.59 * green) + (0.11 * blue); | |
| var gray = (red + green + blue) / 3; | |
| //puts the gray scale on each pixel color | |
| imgData.data[i * 4 + 0] = gray;//red | |
| imgData.data[i * 4 + 1] = gray;//blue | |
| imgData.data[i * 4 + 2] = gray;//green | |
| imgData.data[i * 4 + 3] = gray;//alpha (index 3) | |
| } | |
| console.log(imgData.data); | |
| ctx.putImageData(imgData, 0, 0); | |
| } | |
| </script> | |
| </body> | |
| </html> |
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