Crop rectangle with specific border color and JAVA cetane background color
I have an image with some rectangles inside it. I only need to crop rectangles with red border and white background using (Java) or JavaCV.
for example, I have a picture of a car with a license plate. Each letter on a license plate has a red rectangle around it and a white background.
what I'm looking for is to crop each letter in one image. letters are indicated by a red rectangle around each and against a white background.
Any suggestions? Thanks to
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Change color space to HSV
IplImage* imgHSV = cvCreateImage(cvGetSize(img), 8, 3); cvCvtColor(img, imgHSV, CV_BGR2HSV);
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Get tint channel only:
cvSplit( imgHSV, h_plane, s_plane, v_plane, 0 );
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Make a threshold for looking for red:
cvInRangeS(h_plane, cvScalar(x, x, x), cvScalar(x, x, x), imgThreshed);
x is the range of red in the HSV color model.
After that, you will have a white and black image, where white will be red in your original image (they should be rectangular as you said).
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Then use the cvFindContours function.
int contoursCont = cvFindContours( imgThreshed, storage,&contours,sizeof(CvContour),CV_RETR_LIST,CV_CHAIN_APPROX_SIMPLE,cvPoint(0,0));
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To have the linked rectangle (rectangle) use (for each path):
CvBox2D box = cvMinAreaRect2( @current_contour@, CvMemStorage* storage CV_DEFAULT(NULL))
To check the background color, count its histogram and check if the bin values are only 255 and 0 (these are the white and black values).
Hope this is helpful!
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You can try this:
- Find a group of red pixels close to each other.
- Find all red pixels associated with them, bucket fill style
- Calculate the bounding box of all found pixels
- Maybe check if all red pixels are close to the edge of the bounding rectangle
- Make sure the inside of the box is mostly white.
This should work as long as your boxes are not interrupted and overlap.
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