Hi Brian,
I went over the code that you posted in your question. I notice that you are first saving the current figure as an image ("dataImage.png"). This captures the gray background of the figure window also as a part of the image. This is different from the variable "image". You can see the difference between the two from the figures shown below. The one on the left is the variable "image" and the one on the right is "imshow(imread("dataImage.png")). You can see that there is an additional white portion in the image on the right. Additionally, the sizes of both "image" and imread("dataImage.png") are different.
In the code that you shared, you are basically finding the corners of imread("dataImage.png") but plotting it on the image represented by the variable "image". To get the right output, modify the code to one of the following:
[imagePoints, boardSize] = detectCheckerboardPoints('dataImage.png');
I1=imread('dataImage.png');
figure,imshow(I1); hold on; plot(imagePoints(:,1), imagePoints(:,2), 'ro');
OR
[imagePoints, boardSize] = detectCheckerboardPoints(image);
figure,imshow(image); hold on; plot(imagePoints(:,1), imagePoints(:,2), 'ro');
I hope this helps.
Regards,
Vidya Viswanathan
