how to extract an image and resize it?

I am enclosing an image. I want to extract only lena from it removing all the black boundaries and re-sizing it to 512x512 image.

Answer 1

[Image Analyst]

Take the vertical and horizontal profiles and then use find() to find the bounding box

verticalProfile = mean(grayImage, 2);
horizontalProfile = mean(grayImage, 1);
topRow = find(verticalProfile, 1, 'first');
bottomRow = find(verticalProfile, 1, 'last');
leftColumn= find(horizontalProfile, 1, 'first');
rightColumn = find(horizontalProfile, 1, 'last');
croppedImage = grayImage(topRow:bottomRow, leftColumn:rightColumn);
[rows, columns, numberOfColorChannels] = size(croppedImage);
if rows ~= 512 || columns ~= 512
  croppedImage = imresize(croppedImage, [512,512]);
end

[Kritika]

this is not working. it just resized the image to 512x512.