当点击按钮时,它会告诉移动设备去相机。一旦相机拍摄了照片,它将提供图像数据(这被称为数据网址吗?)。这是我处理它的代码:
var imagesrc = "data:image/jpeg;base64," + imageData;
var myimage = new Image(500, 500);
myimage.src = imagesrc; <---- to populate the object with the colored image
myimage.src = grayscale(myimage); <---- here I set it to the grayscale image
我想调用一个名为grayscale()
的方法,并使其返回已转换为灰度的图像。 我尝试了以下代码:
function grayscale(image){
var canvasContext = canvas.getContext('2d');
var imgW = image.width;
var imgH = image.height;
canvas.width = imgW;
canvas.height = imgH;
canvasContext.drawImage(image, 0, 0);
var imgPixels = canvasContext.getImageData(0, 0, imgW, imgH);
for(>var y = 0; y < imgPixels.height; y++){
for(>var x = 0; x < imgPixels.width; x++){
var i = (y * 4) * imgPixels.width + x * 4;
var avg = (imgPixels.data[i] + imgPixels.data[i + 1] + imgPixels.data[i + 2]) / 3;
imgPixels.data[i] = avg;
imgPixels.data[i + 1] = avg;
imgPixels.data[i + 2] = avg;
}
}
canvasContext.putImageData(imgPixels, 0, 0, 0, 0, imgPixels.width, imgPixels.height);
dataurl = canvas.toDataURL();
var newimg = "data:image/jpeg;base64," + dataurl;
return newimg;
}
但出于某些原因,它不起作用。它只是不能显示灰度图像。我在网上找到了for循环代码并进行了调整。
toDataURL
已经返回了完整的数据URL,您不需要添加前缀(而且它也不会是JPEG格式)。 - Bergi