Twenty Twelve Theme

Good Day everyone,

I’m currently running a stock version of WordPress and stock version of Twenty Twelve themes. I’m just wondering if there is any way to increase the size of picture we can post to blog because the current one is limiting to only 640 x 480 in picture sizes.

Is there any modification we can do to increase the limit to 1024 x 768? I tried posting but it just automatically resizes the photo to 640 x 480.

Appreciate your guys views on this matter. FYI, I’m linking back my images from Flickr.