OpenCV 3.0中的活动轮廓模型 [英] Active Contour Models in OpenCV 3.0

问题描述

我正在尝试使用C ++中的Opencv 3.0实现Active Contour Models算法. 该算法基于我为MatLab编写的脚本，无法正常运行. 这两个图像显示了两种算法运行的结果.

I'm trying to implement an Active Contour Models algorithm with Opencv 3.0 in C++. This algorithm is based on a script I wrote for MatLab and is not working as it supposed to. This two images shows the result of the two algorithms running.

MatLab脚本:

和OpenCV之一:

在这两个示例中，我对所有ACM参数都使用了相同的值，因此它们应该返回相同的东西，即白色圆圈轮廓. 我怀疑问题出在我的图像能量函数上，因为opencv和matlab中的梯度运算不一样.用于图像能量的matlab脚本为:

In both of them I used the same values for all the ACM parameters, so they should be returning the same thing, the white circle contour. I'm suspecting the problem is my image energy function, since gradient operations in opencv and matlab are not the same. The matlab script for the image energy is:

function [Eext] = get_eext(wl, we, wt, image)

%External Energy
[row,col] = size(image);
eline = image; %eline is simply the image intensities

[grady,gradx] = gradient(image);
eedge = -1 *(gradx .* gradx + grady .* grady);



%masks for taking various derivatives
m1 = [-1 1];
m2 = [-1;1];
m3 = [1 -2 1];
m4 = [1;-2;1];
m5 = [1 -1;-1 1];

cx = conv2(image,m1,'same');
cy = conv2(image,m2,'same');
cxx = conv2(image,m3,'same');
cyy = conv2(image,m4,'same');
cxy = conv2(image,m5,'same');

eterm = zeros(row, col);

for i = 1:row;
    for j= 1:col;
        % eterm as deined in Kass et al Snakes paper
        eterm(i,j) = (cyy(i,j)*cx(i,j)*cx(i,j) -2 *cxy(i,j)*cx(i,j)...
            *cy(i,j) + cxx(i,j)*cy(i,j)*cy(i,j))/((1+cx(i,j)*cx(i,j)...
            + cy(i,j)*cy(i,j))^1.5);
    end;
end;

Eext = (wl*eline + we*eedge + wt*eterm);

在C ++中，我的函数结果如下:

And in C++ my function turned out like this:

Mat get_eext(float wl, float we, float wt, Mat image){

Mat eline, gradx, grady, img_gray, eedge;

//bitdepth defined as CV_32F
image.convertTo(img_gray, bitdepth);

//Convolution Kernels
Mat m1, m2, m3, m4, m5;
m1 = (Mat_<float>(1, 2) << -1, 1);
m2 = (Mat_<float>(2, 1) << -1, 1);
m3 = (Mat_<float>(1, 3) << 1, -2, 1);
m4 = (Mat_<float>(3, 1) << 1, -2, 1);
m5 = (Mat_<float>(2, 2) << 1, -1, -1, 1);

//cvtColor(image, img_gray, CV_BGR2GRAY); <- Not required since image already in grayscale
img_gray.copyTo(eline);

Mat kernelx = (Mat_<float>(1, 3) << -0.5, 0, 0.5);
Mat kernely = (Mat_<float>(3, 1) << -0.5, 0, 0.5);

filter2D(img_gray, gradx, -1, kernelx);
filter2D(img_gray, grady, -1, kernely);

//Edge Energy
eedge = -1 * (gradx.mul(gradx) + grady.mul(grady));

//Termination Energy Convolution
Mat cx, cy, cxx, cyy, cxy, eterm, cxm1, den, cxcx, cxcxm1, cxcxcy, cxcycxy, cycycxx;
filter2D(img_gray, cx, bitdepth, m1);
filter2D(img_gray, cy, bitdepth, m2);
filter2D(img_gray, cxx, bitdepth, m3);
filter2D(img_gray, cyy, bitdepth, m4);
filter2D(img_gray, cxy, bitdepth, m5);

//element wise operations to find Eterm
cxcx = cx.mul(cx);
cxcx.convertTo(cxcxm1, -1, 1, 1);
den = cxcxm1 + cy.mul(cy);
cv::pow(den, 1.5, den);
cxcxcy = cxcx.mul(cy);
cxcycxy = cx.mul(cy);
cxcycxy = cxcycxy.mul(cxy);
cycycxx = cy.mul(cy);
cycycxx = cycycxx.mul(cxx);
eterm = (cxcxcy - 2 * cxcycxy + cycycxx);
cv::divide(eterm,den,eterm,-1);

//Image energy
Mat eext;
eext = wl*eline + we*eedge + wt*eterm;
return eext;}

有人知道怎么了吗?

推荐答案

按照David Doria的要求，这里是经过一些更正的get_eext函数的最终版本.这个版本对我来说效果很好.

As asked by David Doria, here is the final version of the function get_eext after a few corrections. This version worked fine for me.

Mat config_eext(float wl, float we, float wt, Mat image)
{
Mat eline, gradx, grady, img_gray, eedge;

//bitdepth defined as CV_32F
image.convertTo(img_gray, bitdepth);

//Convolution Kernels
Mat m1, m2, m3, m4, m5;
m1 = (Mat_<float>(1, 2) << 1, -1);
m2 = (Mat_<float>(2, 1) << 1, -1);
m3 = (Mat_<float>(1, 3) << 1, -2, 1);
m4 = (Mat_<float>(3, 1) << 1, -2, 1);
m5 = (Mat_<float>(2, 2) << 1, -1, -1, 1);

img_gray.copyTo(eline);

//Kernels de gradiente
Mat kernelx = (Mat_<float>(1, 3) << -1, 0, 1);
Mat kernely = (Mat_<float>(3, 1) << -1, 0, 1);

//Gradiente em x e em y
filter2D(img_gray, gradx, -1, kernelx);
filter2D(img_gray, grady, -1, kernely);

//Edge Energy como definido por Kass
eedge = -1 * (gradx.mul(gradx) + grady.mul(grady));

//Termination Energy Convolution
Mat cx, cy, cxx, cyy, cxy, eterm(img_gray.rows, img_gray.cols, bitdepth), cxm1, den, cxcx, cxcxm1, cxcxcy, cxcycxy, cycycxx;
filter2D(img_gray, cx, bitdepth, m1);
filter2D(img_gray, cy, bitdepth, m2);
filter2D(img_gray, cxx, bitdepth, m3);
filter2D(img_gray, cyy, bitdepth, m4);
filter2D(img_gray, cxy, bitdepth, m5);

//element wise operations to find Eterm
cxcx = cx.mul(cx);
cxcx.convertTo(cxcxm1, -1, 1, 1);
den = cxcxm1 + cy.mul(cy);
cv::pow(den, 1.5, den);
cxcxcy = cxcx.mul(cy);
cxcycxy = cx.mul(cy);
cxcycxy = cxcycxy.mul(cxy);
cycycxx = cy.mul(cy);
cycycxx = cycycxx.mul(cxx);
eterm = (cxcxcy - 2 * cxcycxy + cycycxx);
cv::divide(eterm, den, eterm, -1);

//Image energy
Mat eext;
eext = wl*eline + we*eedge + wt*eterm;
return eext;
}

希望有帮助！

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