matlab: read subsection of an image

I have a sequence of large images I would like to load into matlab and then apply some processing too. Due to the images size, reading them in takes a long time, and fills the computer memory very fast.

However, I am only interested in the middle section of the images, a region of about 100 by 100 pixels or so.

Is there a way to only read in that section of the image, therefore saving time, and memory?

Currently I am using:

ROIx = 450:550;
 ROIy = 650:750;
 image = double( imread( filename ) );
 image = image(ROIx, ROIy);
 

However, imread() loads the whole image, and this takes a long time. Is there a way only to read the part I am interested in?

(One procedure would be to go through and crop each image into a smaller one and resave it. But I would prefer not to crop the images).

Thanks,
labjunky

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