Generating multiple ROIs from a single image. (Automatic generation of ROI required)

I have this code below which works fine, but it is time consuming.

Is there a better and faster solution possible?

if true im = imread('my_image.png'); I = single(rgb2gray(im))/255;

%getting height and width of image
width = size(im,2);
height = size(im,1);

k = 15;
x = randsample(height,k);
y = randsample(width,k);
sP = horzcat(x,y);

for i = 1:k
     if (((sP(i,1)+100) < height) &&  ((sP(i,2)+100) < width) &&  ((sP(i,1)-100) > 0) &&  ((sP(i,2)-100) > 0))
                x_min = sP(i,1)-100;
                x_max =sP(i,1) + 100;
                y_min = sP(i,2)-100;
                y_max = sP(i,2)+100;
                roi = im(x_min:x_max,y_min:y_max,:);
              imwrite(roi,['MYlocation' strcat(num2str(i) ,'_roi.png')],'png');
    elseif((((sP(i,1)+200) < height) || ((sP(i,1)- 200) > 0)) && (((sP(i,2)+200) < width) || ((sP(i,2)- 200) > 0)))

        if ((sP(i,1)+200) < height)
      x_min = sP(i,1);
      x_max = (sP(i,1)+200);
        elseif ((sP(i,1)- 200) > 0)
            x_min = sP(i,1)-200;
            x_max = sP(i,1);
         end
      if((sP(i,2)+200) < width)
        y_min = sP(i,2);
        y_max = (sP(i,2)+200);
      else
          y_min = (sP(i,2)- 200);
          y_max = sP(i,2);
      end
      roi = im(x_min:x_max,y_min:y_max,:);
      imwrite(roi,['MYlocation' strcat(num2str(i) ,'_roi.png')],'png');
         else
          continue; 
      end
  end

end

Answer 1

[Image Analyst]

It's not time consuming on my computer - it's pretty fast.

Elapsed time is 0.675276 seconds.

And that even included an imshow() to see what I was saving. How long does it take for you?

Answer 2

[bidisha]

Elapsed time is 5.131721 seconds. Right now I am doing it for an image of size 226 by 502. I might be using larger ROIs and hence generate more number of samples from it.