Copy image using Rect() and copyTo()

asked 2016-06-08 09:29:22 -0500

VanGog gravatar image

I followed the tutorial about dft and it worked. But I tried to remake it to a class. Small changes I did. In the tutorial the are the square if images swapped and I do not want them to be swapped. I have changed the names of variables and this is what I have:

cv::Mat tl(logScaled, Rect(0, 0, half_width, half_height)); // Top-Left - Create a ROI per quadrant
cv::Mat tr(logScaled, Rect(cx, 0, half_width, half_height)); // Top-Right
cv::Mat bl(logScaled, Rect(0, cy, half_width, half_height)); // Bottom-Left
cv::Mat br(logScaled, Rect(cx, cy, half_width, half_height)); // Bottom-Right
tl.copyTo(Images[file_no]);
tr.copyTo(Images[file_no]);
bl.copyTo(Images[file_no]);
br.copyTo(Images[file_no]);
cv::normalize(Images[file_no], Images[file_no], 0, 1, NORM_MINMAX); 
cv::imshow("spectrum magnitude", Images[file_no]);
cv::waitKey();

Only 1/4 of the image is displayed so I think it is the top left (or bottom right?) square. How to complete this successfully to copy all the 4 squares/images to the image? Images[file_no] keeps the original image untill I copy the squares onto it. It looks like the header is overwritten but how to solve it?

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Comments

Not too sure about the purpose of these lines. Why do you split logScaled in 4 pieces if you then want to join the very same 4 pieces to reconstruct the image? Your problem has an easy solution, but I don't think it is even needed

LorenaGdL gravatar imageLorenaGdL ( 2016-06-08 10:34:23 -0500 )edit

@LorenaGdL Thanks for your answer. Good idea. I skipped those splitting and normalized the image and now it fits to the original size. Still, I am interested why the solution in tutorial works and mine does not. It seems there are exactly same approaches, except I avoided swapping those squares.

VanGog gravatar imageVanGog ( 2016-06-08 11:05:59 -0500 )edit

@VanGog please, link the tutorial

LorenaGdL gravatar imageLorenaGdL ( 2016-06-08 11:46:30 -0500 )edit