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I want to change a colorful image to gray scale, but I have a security error when I try to use getImageData.
Uncaught SecurityError: Failed to execute 'getImageData' on 'CanvasRenderingContext2D': The canvas has been tainted by cross-origin data.
I know this error has been discussed everywhere, but none of them have a clear solution. Please help!
<html>
<script>
function grayscale()
{
var myCanvas = document.getElementById("c1");
var myCanvasContext = myCanvas.getContext("2d");
var img = document.getElementById("myImage");
img.crossOrigin = "anonymous";
var imgWidth = img.width;
var imgHeight = img.height;
myCanvas.width = imgWidth;
myCanvas.height = imgHeight;
myCanvasContext.drawImage(img,0,0);
var imageData = myCanvasContext.getImageData(0,0, imgWidth, imgHeight);
for (j=0; j<imageData.height; i++)
{
for (i=0; i<imageData.width; j++)
{
var index=(i*4)*imageData.width+(j*4);
var red=imageData.data[index];
var green=imageData.data[index+1];
var blue=imageData.data[index+2];
var alpha=imageData.data[index+3];
var average=(red+green+blue)/3;
imageData.data[index]=average;
imageData.data[index+1]=average;
imageData.data[index+2]=average;
imageData.data[index+3]=alpha;
}
}
}
</script>
<body>
<img id="myImage" onload="grayscale()" src="doggie.png"></img>
<canvas id = "c1" width = "200px" height = "200px" style="border:1px solid #000000;">
</canvas>
</body>
</html>
238
Recently I have the same problem. You must have image on the same domain (as your code) or set cross-origin on server where the image is.
Access-Control-Allow-Origin: *
97
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