Cropping out two images from one big image by manually selecting the cropping are

How can I crop two images out from one big image by manually selecting the region for cropping out with a rectangle for example? Additionally, how can I extract the rows and columns that I selected with the rectangle?

Answer 1

[Ameer Hamza]

Try this code

img = imread('pears.png');

figure();
ax1 = axes();
imshow(img, 'Parent', ax1)
fprintf('Drag a rectange on the image.\n')
roi = drawrectangle(ax1);

img_small = imcrop(img, roi.Position);
figure();
ax2 = axes();
imshow(img_small, 'Parent', ax2)

[windmill]

Thnak you, it worked! Is there any way I can display the rows and columns start and ends of the rectangle?

[Ameer Hamza]

Yes, check the value of

roi.Position

It contains [x y width height] of the extacted image. x and y are coordinates (in pixels) of the top left corner of the rectangle.

[windmill]

Thanks, I got it! I just tried to modfify the code so I can use my images that I converted to grayscale images, but I don't know why it won't work anymore... Do you see the problem?

image = imread('Test016.tif');
max(max(image))
image2 = mat2gray(image)*255
figure();
ax1 = axes();
imshow(image2, 'Parent', ax1)
fprintf('Draw the ROI on the image using the rectangle.\n')
roi = drawrectangle(ax1);
roiPos=roi.Position;
cropped_image = imcrop(image2, roi.Position);
figure();
ax2 = axes();
imshow(cropped_image, 'Parent', ax2)

[Ameer Hamza]

Try this code

image = imread('pears.png');
image2 = rgb2gray(image);
figure();
ax1 = axes();
imshow(image2, 'Parent', ax1)
fprintf('Draw the ROI on the image using the rectangle.\n')
roi = drawrectangle(ax1);
roiPos=roi.Position;
cropped_image = imcrop(image2, roi.Position);
figure();
ax2 = axes();
imshow(cropped_image, 'Parent', ax2)

Answer 2

[Image Analyst]

Did you check out the documentation for imcrop(), or rbbox()?

[windmill]

Thank you, haven't heard about rbbox() before, but will make sure to check it out