How to cut image to smaller pieces? [closed]

asked 2016-01-11 10:03:49 -0600

jaqqu7 gravatar image

I need to cut image in half and each of them save as different one. For example I have image in grayscale and I try to do it like this:

halfImg[0] = Mat(greyimg, Rect(0, 0, 163, 93)).clone();
halfImg[1] = Mat(greyimg, Rect(164, 0, 327, 93)).clone();

but the second one generates this error:

image description

Is there another way to do it in Open CV?

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Closed for the following reason the question is answered, right answer was accepted by sturkmen
close date 2020-11-10 02:17:22.292195

Comments

1

Your Rect expects x, y, width and height, so if you give 164(x)+327(width)=491 on x, does the coordinate exists? What is the size of your greyImage?

thdrksdfthmn gravatar imagethdrksdfthmn ( 2016-01-11 10:22:23 -0600 )edit

So, Is it possible that I just keep using Rect() wrong way? My image has size of 327x93.

jaqqu7 gravatar imagejaqqu7 ( 2016-01-11 10:26:47 -0600 )edit

take a look at http://answers.opencv.org/question/82641 you can adapt @thdrksdfthmn 's answer to divide your image vertically

sturkmen gravatar imagesturkmen ( 2016-01-11 10:28:52 -0600 )edit
1

Thanks! Now I understand what I did wrong. I did not know that the coordinates add up in this function. Your first comment helps me alot.

halfImage[0] = Mat(greyimg, Rect(0, 0, 163, 93)).clone();
halfImage[1] = Mat(greyimg, Rect(164, 0, 163, 93)).clone();

This is correct way.

jaqqu7 gravatar imagejaqqu7 ( 2016-01-11 10:33:14 -0600 )edit

it is still uncorrect. tell me why?

sturkmen gravatar imagesturkmen ( 2016-01-11 10:40:56 -0600 )edit

No, this is correct now.

jaqqu7 gravatar imagejaqqu7 ( 2016-01-11 10:47:15 -0600 )edit
2

you have two images both witdh is 163 :) check this one

cv::Rect leftROI( 0, 0, greyimg.cols / 2, greyimg.rows );
cv::Rect rightROI( leftROI.width, 0, greyimg.cols - leftROI.width , greyimg.rows );
halfImage[0] = greyimg( leftROI ).clone();
halfImage[1] = greyimg( rightROI ).clone();

or

halfImage[0] = Mat(greyimg, Rect(0, 0, 163, 93)).clone();
halfImage[1] = Mat(greyimg, Rect(163, 0, 164, 93)).clone();
sturkmen gravatar imagesturkmen ( 2016-01-11 10:58:46 -0600 )edit
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