how to crop image from detected rectangle.?

 clear all;clc
boxImage = imread('IMG.jpg');
boxImage = boxImage(:,:,3);
figure; imshow(boxImage);
title('Image of a Box');
sceneImage = imread('IMG1.jpg');
sceneImage = sceneImage(:,:,3);
figure; imshow(sceneImage);
title('Image of a Cluttered Scene');
boxPoints = detectSURFFeatures(boxImage);
scenePoints = detectSURFFeatures(sceneImage);
figure; imshow(boxImage);
title('100 Strongest Feature Points from Box Image');
hold on;
plot(boxPoints.selectStrongest(100));
figure; imshow(sceneImage);
title('300 Strongest Feature Points from Scene Image');
hold on;
plot(scenePoints.selectStrongest(300));
[boxFeatures, boxPoints] = extractFeatures(boxImage, boxPoints);
[sceneFeatures, scenePoints] = extractFeatures(sceneImage, scenePoints);
boxPairs = matchFeatures(boxFeatures, sceneFeatures);
matchedBoxPoints = boxPoints(boxPairs(:, 1), :);
matchedScenePoints = scenePoints(boxPairs(:, 2), :);
figure;
showMatchedFeatures(boxImage, sceneImage, matchedBoxPoints, ...
    matchedScenePoints, 'montage');
title('Putatively Matched Points (Including Outliers)');
[tform, inlierBoxPoints, inlierScenePoints] = ...
    estimateGeometricTransform(matchedBoxPoints, matchedScenePoints, 'affine');
figure;
showMatchedFeatures(boxImage, sceneImage, inlierBoxPoints, ...
    inlierScenePoints, 'montage');
title('Matched Points (Inliers Only)');
boxPolygon = [1, 1;...                           % top-left
        size(boxImage, 2), 1;...                 % top-right
        size(boxImage, 2), size(boxImage, 1);... % bottom-right
        1, size(boxImage, 1);...                 % bottom-left
        1, 1];                   % top-left again to close the polygon
    newBoxPolygon = transformPointsForward(tform, boxPolygon);

    figure; imshow(sceneImage);
hold on;
line(newBoxPolygon(:, 1), newBoxPolygon(:, 2), 'Color', 'y');
title('Detected Box');

After ruuning this code, i am able to detect features of one image into another and it draws a rectange at detected portion. Now i want to crop that detected portion and want to save.. How to crop it and save it.?

Answer 1

[Image Analyst]

Have you tried imcrop() and imwrite()?

[Nimisha]

below above code i tried

 imcrop(newBoxPolygon)

But it asks me to crop manually.. I want to crop and save automatically

[Dima Lisin]

You would need to pass the image into imcrop, in addition to the bounding box.

I2 = imcrop(I1,bbox);

Please check the documentation for imcrop.

[Nimisha]

 P = newBoxPolygon(:, 1)
 W = P(1);
 X = P(2) - W;
 Q =  newBoxPolygon(:, 2)
 Y = Q(1);
 Z = Q(3) - Q(1);
 imcrop(sceneImage,[W X Y Z])

I tried with this code, but detects wrong part. Please correct it.

[Image Analyst]

I'm not sure the format of newBoxPolygon, but try this:

xLeft = min(newBoxPolygon(:, 1))
xRight = max(newBoxPolygon(:, 1))
yTop = min(newBoxPolygon(:, 2))
yBottom = max(newBoxPolygon(:, 2))
height = abs(yBottom - yTop)
width = abs(xRight - xLeft);
croppedImage = imcrop(sceneImage, [xLeft, yTop, width, height])
imshow(croppedImage);

[Sharmin Akhter]

thanx.. i am also facing the same problem..

[bhagyashri kapre]

xLeft = min(newBoxPolygon(:, 1))

xRight = max(newBoxPolygon(:, 1))

yTop = min(newBoxPolygon(:, 2))

yBottom = max(newBoxPolygon(:, 2))

height = abs(yBottom - yTop)

width = abs(xRight - xLeft);

croppedImage = imcrop(sceneImage, [xLeft, yTop, width, height])

imshow(croppedImage);

Thank you above answer is helful for me in my project