复制代码 代码如下:

function getHistogram(imageData) {

var arr = [];

for (var i = 0; i < 64; i++) {

arr[i] = 0;

}

var data = imageData.data;

var pow4 = Math.pow(4, 2);

for (var i = 0, len = data.length; i < len; i += 4) {

var red = (data[i] / 64) | 0;

var green = (data[i + 1] / 64) | 0;

var blue = (data[i + 2] / 64) | 0;

var index = red * pow4 + green * 4 + blue;

arr[index]++;

}

return arr;

}

function cosine(arr1, arr2) {

var axb = 0,

a = 0,

b = 0;

for (var i = 0, len = arr1.length; i < len; i++) {

axb += arr1[i] * arr2[i];

a += arr1[i] * arr1[i];

b += arr2[i] * arr2[i];

}

return axb / (Math.sqrt(a) * Math.sqrt(b));

}

function gray(imgData) {

var data = imgData.data;

for (var i = 0, len = data.length; i < len; i += 4) {

var gray = parseInt((data[i] + data[i + 1] + data[i + 2]) / 3);

data[i + 2] = data[i + 1] = data[i] = gray;

}

return imgData;

}

有个问题，假如图片是灰色的跟原图进行比较，那么要比较相似度，需要将图片都转成灰色的，即使用上面代码的gray函数来处理