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.