如何在opencv中使用OTSU阈值? [英] How to use the OTSU Threshold in opencv?

问题描述

我使用的是固定的阈值，但事实证明这对我不太好.然后，有人告诉我有关大津的门槛.如何在我的代码中使用它? 我读了一下，但我不太了解.有人可以告诉我如何在OpenCV中使用otsu阈值吗?

I was using a fixed threshold but turns out that it's not so good for me. Then, someone told me about the otsu threshold. How can I use it in my code? I read about it and I don't understand very well. Could someone explain to me how to use it in OpenCV the otsu threshold?

这是我的代码:

#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;

int main ( int argc, char **argv )
{
   Mat im_gray = imread("img3.jpg",CV_LOAD_IMAGE_GRAYSCALE);

   Mat im_rgb  = imread("img3.jpg");
   cvtColor(im_rgb,im_gray,CV_RGB2GRAY);

   Mat img_bw = im_gray > 115;

   imwrite("img_bw3.jpg", img_bw);

   return 0;
}  

为此，我必须将阈值更改为要转换为二进制图像的任何图像.我发现了:

With this I have to change the threshold to any image that I want to convert to binary. I found this:

cvThreshold(scr, dst, 128, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);

是吗? 我不太了解，因此，我不知道如何适应我的代码.

Is that right? I don't understand very well and because of that, didn't know how I could adapt to my code.

推荐答案

以下行进行otsu阈值操作:

cv::threshold(im_gray, img_bw, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);

• im_gray是源8位图像，
• img_bw是结果，
• 0表示阈值水平，实际上由于我们使用了CV_THRESH_OTSU标志而被省略了，
• 255是要分配给结果中各个像素的值(即，分配给源中的值大于计算出的阈值水平的所有像素)
• CV_THRESH_BINARY | CV_THRESH_OTSU是执行Otsu阈值化的必需标志.因为实际上我们想执行二进制阈值处理，所以我们将CV_THRESH_BINARY(您可以使用opencv提供的5个标志中的任何一个)与CV_THRESH_OTSU
结合使用
• im_gray is a source 8-bit image,
• img_bw is a result,
• 0 means threshold level which actually is omitted because we used CV_THRESH_OTSU flag,
• 255 is a value that is going to be assigned to respectively pixels in the result (namely, to all pixels which value in the source is greater then computed threshold level)
• CV_THRESH_BINARY | CV_THRESH_OTSU is a required flag to perform Otsu thresholding. Because in fact we would like to perform binary thresholding, so we use CV_THRESH_BINARY (you can use any of 5 flags opencv provides) combined with CV_THRESH_OTSU

文档链接: http://docs.opencv.org/modules/imgproc/doc/miscellaneous_transformations.html#threshold

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