昨天看了阮一峰老师的文章:《相似图片搜索原理》,于是把直方图和向量那块算法用js实现了一下,
源码如下:
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。