java - Algorithm to find neighboring subimages -

i have image , extracting subimage feed neural network. attempting calculate average output of subimages in same neighborhood.

so if have original image (m x n pixels) , found subimage @ (sub_x, sub_y) size (sub_width , sub_height), need extract subimages same size (sub_width , sub_height) @ (sub_x + m, sub_y + n) m , n go 1 - 3.

i have working solution:

for (int subx = (x-3); subx < (x+4); subx++)     (int suby = (y-3); suby < (y+4); suby++)       if ( (subx > 0) && (suby > 0) )         if ( ((subx + width) < img.getwidth()) && ((suby + height) < img.getheight()) ){             counter++;             testingimage = img.getsubimage(subx, suby, width, height);               } 

x,y, width, , height integers of original subimage found.

img original full sized bufferedimage.

i'm not happy performance though. there faster/smarter way this?

here's 1 simple thing can do: rid of conditions inside loops. calculate ranges first, once , run loops without range checks.

int subxstart = max(x-3, 0); int subystart = max(y-3, 0); int subxend = min(x+4, img.getwidth() - width); int subyend = min(y+4, img.getheight() - height); (int subx = subxstart; subx < subxend; subx++) {     (int suby = subystart; suby < subyend; suby++) {         counter++;         testingimage = img.getsubimage(subx, suby, width, height);         // run neural net     } } 

you can try switching order of loops. order matches memory ordering should considerably faster.