[英]OpenCV: How can I find the color inside a contour/polygon?
Here is what I have 这就是我所拥有的
im = cv2.imread('luffy.jpg')
gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
ret,thresh = cv2.threshold(gray,127,255,0)
contours,h = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
for cnt in contours:
// return color inside of the contour here
mask = np.zeros(cnt.shape[:2],np.uint8)
mean = cv2.mean(cant,mask) // I think this is promising but so far it returns arrays with just zeros. I think its because I used np.zeros above to find the mask....
moment = cv2.moments(cnt) //maybe this will help?
I can find no such openCV function built in. I assume perhaps you can do it with the moments? 我找不到内置的openCV函数。我想也许你可以用这些时刻做到这一点? How can I achieve this?? 我怎么能实现这个?
EDIT: with the proposed solution given by Zaw Lin I have this input image: 编辑:使用Zaw Lin提出的解决方案我有这个输入图像:
and this output image: 这个输出图像:
This gets the average color inside each contour and draws contours with that color to final image. 这将获得每个轮廓内的平均颜色,并将具有该颜色的轮廓绘制到最终图像。
import cv2
import numpy as np
im = cv2.imread('/home/zawlin/test.png')
gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
contours,h = cv2.findContours(gray,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
final = np.zeros(im.shape,np.uint8)
mask = np.zeros(gray.shape,np.uint8)
for i in xrange(0,len(contours)):
mask[...]=0
cv2.drawContours(mask,contours,i,255,-1)
cv2.drawContours(final,contours,i,cv2.mean(im,mask),-1)
cv2.imshow('im',im)
cv2.imshow('final',final)
cv2.waitKey(0)
i think function mean with a mask image is the only way to get color inside a contour but sorry i can't show it by Python code. 我认为功能意味着一个掩码图像是在轮廓内获得颜色的唯一方法但很遗憾我无法通过Python代码显示它。
you can get bounding box of a contour by boundingRect
and use it to get image ROI from source image and binarized image for masking ( be aware of cloning binarized image because findcontour
destroys it) 你可以通过边界轮廓的箱boundingRect
并用它来从源图像和二值图像获取图像ROI掩蔽(注意克隆二值图像的,因为findcontour
破坏它)
maybe a sample c++ will be useful ( sorry for my poor english.) 也许一个示例c ++将是有用的(抱歉我的英语不好。)
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;
int main( int, char** argv )
{
/// Load source image
Mat src = imread(argv[1]);
if (src.empty())
{
cerr << "No image supplied ..." << endl;
return -1;
}
/// Convert image to gray
Mat src_gray;
cvtColor( src, src_gray, COLOR_BGR2GRAY );
threshold( src_gray, src_gray, 50, 255, THRESH_BINARY );
imshow( "src_gray", src_gray );
/// Find contours
vector<vector<Point> > contours;
findContours( src_gray.clone(), contours, RETR_TREE, CHAIN_APPROX_SIMPLE );
Mat resImage0 = src.clone();
Mat resImage1 = src.clone();
/// Draw contours
for( size_t i = 0; i< contours.size(); i++ )
{
Scalar color = Scalar( 0, 0, 255 );
Rect _boundingRect = boundingRect( contours[i] );
Scalar mean_color0 = mean( src( _boundingRect ) );
Scalar mean_color1 = mean( src( _boundingRect ), src_gray( _boundingRect ) );
drawContours( resImage0, contours, (int)i, mean_color0, FILLED );
drawContours( resImage1, contours, (int)i, mean_color1, FILLED );
}
/// Show in a window
imshow( "src", src );
imshow( "resImage0", resImage0 );
imshow( "resImage1", resImage1 );
waitKey(0);
return(0);
}
input image: 输入图像:
output images: 输出图像:
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