Imaging apparatus with scene adaptive auto exposure compensation

摘要

A method adjusts an auto exposure target in an auto-exposure operation on a sequence of images, such as a sequence of infrared images. The method comprises: obtaining a histogram of at least one of the images; applying a weighted histogram table to the histogram to obtain weighted histogram bins wherein at least some bins in the histogram containing saturated pixels are assigned a higher weighting value and at least some bins in the histogram containing unsaturated pixels are assigned a lower weighting value, and summing the weighted histogram bins to obtain a saturation score and decreasing an auto exposure target for an auto exposure operation when the saturation score exceeds a first threshold value, and increasing the auto-exposure target when the saturation score is below the first threshold value and the image is underexposed.

主权项

1. A method for adjusting an auto exposure target in an auto-exposure operation on a sequence of images, comprising:
(a) prior to obtaining a histogram of an image, masking static or mostly static background saturated pixels in the image by identifying pixels in the image that have exceeded a saturation threshold a selected number of times over a time period, and applying a mask to the identified pixels such that the masked pixels are not included in the histogram; (b) obtaining the histogram of the image; (c) applying a weighted histogram table to the histogram to obtain weighted tonal value bins wherein at least some bins in the histogram containing oversaturated pixels are assigned a higher weighting value and at least some bins in the histogram containing non-saturated pixels are assigned a lower weighting value; and (d) summing the weighted histogram bins to obtain a saturation score and decreasing an auto exposure target for an auto exposure operation when the saturation score indicates that the image is oversaturated, and increasing the auto exposure target when the saturation score indicates that the image is non-saturated and when the image is underexposed.