Adaptive Image Thresholding for Light Source Identification

A non-transitory computer-readable medium comprising computer-executable instructions, the instructions including:

• receiving an image pyramid representing a tone-mapped image by a reference pixel array of low resolution, and by one or more test pixel arrays of higher resolution than the reference pixel array;
• comparing pixel values of test pixels in the image with respective brightness thresholds, wherein a light source is identified at a position at which a test pixel value exceeds a respective brightness threshold;
• and
• for each test pixel, defining the respective brightness threshold as a non-linear function of a pixel value of a reference pixel in the reference pixel array which has an area in the image which includes the position of the test pixel and which has a pixel value which is a mean pixel value of the test pixels in the area in the image of the reference pixel,
• wherein the non-linear function is of form T(x,y)=(1/A)*(A*I″(x,y))γ+β, for threshold value T at test pixel image position (x,y), reference pixel value I″(x,y), maximum pixel value A, gamma correction coefficient γ, and linear offset β.