Automatic exposure time selection for imaging tissue

The invention relates to a system for automatically adjusting an exposure time to improve or otherwise optimize a dynamic range of a digital image. The system includes a camera configured to capture an image of a subject within the field of view at a first exposure time. The captured image is composed of multiple pixels, with each pixel having a respective intensity value. The system further includes a shutter or suitable control configured to control an exposure time of the camera. A controller configured to carryout the following steps including: (a) querying a frequency distribution of pixel intensity values; (b) determining an effective "center of mass" of such a distribution, or histogram, to determine an adjusted exposure time; and (c) capturing a second image of the subject at the adjusted exposure time thereby obtaining an image with an improved or optimal dynamic range.