标签:direction expressed 元素 高斯函数 ica tom cal core aac
Let’s look for corners. Since corners represents a variation in the gradient in the image, we will look for this “variation”.
Consider a grayscale image . We are going to sweep a window (with displacements in the x direction and in the right direction) and will calculate the variation of intensity.
where:
Since we are looking for windows with corners, we are looking for windows with a large variation in intensity. Hence, we have to maximize the equation above, specifically the term:
Using Taylor expansion:
Expanding the equation and cancelling properly:
Which can be expressed in a matrix form as:
Let’s denote:
So, our equation now is:
A score is calculated for each window, to determine if it can possibly contain a corner:
where:
a window with a score greater than a certain value is considered a “corner”
中文说明:
根据上述讨论,可以将Harris图像角点检测算法归纳如下,共分以下五步:
1. 计算图像I(x,y)I(x,y)在XX和YY两个方向的梯度Ix、IyIx、Iy。
2. 计算图像两个方向梯度的乘积。
3. 使用高斯函数对I2x、I2y和IxyIx2、Iy2和Ixy进行高斯加权(取σ=1σ=1),生成矩阵MM的元素A、BA、B和CC。
4. 计算每个像素的Harris响应值RR,并对小于某一阈值tt的RR置为零。
5. 在3×33×3或5×55×5的邻域内进行非最大值抑制,局部最大值点即为图像中的角点。
标签:direction expressed 元素 高斯函数 ica tom cal core aac
原文地址:http://www.cnblogs.com/duimu/p/6393156.html