Javascript image similarity algorithm implementation js implementation of histogram and vector algorithm_javascript skills

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