I have an image that when I apply a binary threshold on it, it gives a different result compared to when it is in an image with other things. I’m not sure if I’m setting the parameters for the thresholding function incorrectly as I took the example from the OpenCV documentation. Link to documentation: https://docs.opencv.org/4.x/d7/d4d/tutorial_py_thresholding.html
In my test program, I read in two images. One where the object is by itself and another where it is in an image with other objects. When I applied the threshold to the image1 I got the result I wanted. However, when I applied the threshold to image2 I partially got the result I wanted, but one of the blocks did not threshold correctly. Any ideas as to what may be causing this?
#Reading in image1 img1 = cv2.imread("Templates/YellowBlocks/SS.png", cv2.IMREAD_COLOR) #Reading in image2 img2 = cv2.imread("Test Program 1.png", cv2.IMREAD_COLOR) #Converting image1 to grayscale grayImg1 = cv2.cvtColor(img1, cv2.COLOR_BGR2GRAY) #Converting image2 to grayscale grayImg2 = cv2.cvtColor(img2, cv2.COLOR_BGR2GRAY) #Applying a binary threshold on image1 to show text in black and white ret1,thresh1 = cv2.threshold(grayImg1, 0, 255,cv2.THRESH_OTSU+cv2.THRESH_BINARY) #Applying a binary threshold on image2 to show text in black and white ret2,thresh2 = cv2.threshold(grayImg2, 0, 255,cv2.THRESH_OTSU+cv2.THRESH_BINARY) #Displaying image1 cv2.imshow('img1', img1) #Displaying thresholded image1 cv2.imshow('thresh1', thresh1) #Displaying image2 cv2.imshow('img2', img2) #Displaying thresholded image2 cv2.imshow('thresh2', thresh2) cv2.waitKey(0)
This is because of your usage of OTSU. It sets some sort of automatic threshold. Please refer to the following link