How to optimize image cropping?

I have a problem with this function 'Crop_sample', inside the 'I_reduction1' function. I got 'out of memory'. I need to optimize it, but I don't know what tools I could use. So, the function crops the mask, I, and IOB matrices based on the region of interest found in the input mask, and returns the cropped versions of these matrices as new_mask, new_I, and new_IOB, respectively. These cropped matrices will have dimensions determined by the size of the region of interest within the input mask. Given the additional information that I and IOB are matrices of dimensions 640x640x1600. Please help me. Maybe with some Image Processing Toolbox would be better, but I tried and nothing works.

I=ones(640,640,1600);
IOB=ones(640,640,1600);
load mask.mat;
Ired= I_Reduction1(roi1, I, IOB);