How to Crop the detected image

I am following the object detection from this link: http://www.mathworks.com/help/vision/examples/object-detection-in-a-cluttered-scene-using-point-feature-matching.html#btt5qyu

Is there any way to crop only the box? Or I want to make the image black or white except the box. ex)

Please give me some tip! Thank you!

Answer 1

[Image Analyst]

It already is black around the image. Do you want it white? If it's a gray scale image you can do it roughly using

grayImage(grayImage==0) = 255;  % May not be perfect

though that could turn black pixels inside the box white also. There is a more robust way to get a perfect rectangle using imfill() and regionprops(). Let me know if you need that. Otherwise see the FAQ:

http://matlab.wikia.com/wiki/FAQ#How_do_I_mask_an_image.3F

[MoonSik]

The image in my question is desired image. I am sorry for confusion. If you follow the link that I put on. You will see the original image.

Thank you for your reply.

[Image Analyst]

OK, now I see the original image and the "cropped" or detected template image masked out of it. I still don't know what you want to do. Did you look at my answer (specifically the question in there if you want it white instead of black)? Did you see the example link about how to mask a region? Maybe it would help if you posted an image of the desired output image so I know what you want. Also state which image is the "starting" image.

[Sufyan Salim]

I am using the same algorithm though i want it to automatically crop the detected box object in the end and save it as a new image.... how do i do it?

[Image Analyst]

You can use your mask to find the corners:

[rows, columns] = find(mask);
croppedImage = grayImage(rows(1):rows(end), columns(1):columns(end), :);
imwrite(croppedImage, filename);