Entropy maximization based auto-exposure

An image capture apparatus comprising:

• an image sensor;
• a motion sensor;
• and
• an auto-exposure unit configured to:
• obtain, from the image sensor, an input image signal representing an input image captured during an exposure interval;
• obtain, from the motion sensor, motion data indicating motion of the image capture apparatus during the exposure interval;
• obtain image information-amount data for the input image, wherein the image information-amount data is a sum of pixel information-amount data, wherein, for each pixel, the pixel information-amount data is obtained by:
• in response to a determination that an input value for the pixel is a maximum pixel value, using zero as an information-amount value for the pixel;
• and
• in response to a determination that the input value for the pixel is within the maximum pixel value:
• obtaining a signal level information-amount for the pixel as the base two logarithm of a signal-to-noise ratio for the pixel, wherein the signal-to-noise ratio is a ratio of the input value to a noise value for the pixel, and wherein the noise value for the pixel is modeled as a square root of a sum of a first defined value and a product of a second defined value and the input value of the pixel;
• and
• using a motion blur adjusted value for the pixel as the information-amount value for the pixel, wherein the motion blur adjusted value for the pixel is obtained based on the signal level information-amount for the pixel and the motion data;
• obtain derivative information-amount data based on the information-amount data and a candidate exposure adjustment;
• and
• obtain an information-amount maximizing exposure interval based on the information-amount data and the derivative information-amount data, wherein the image capture apparatus is configured to control the image sensor to obtain a subsequent input image signal representing a subsequent input image captured during the information-amount maximizing exposure interval, and output or store information representing the subsequent input image.