FIXED PATTERN NOISE REDUCTION AND HIGH SPATIAL FREQUENCY FILTERING USING VARI-FOCUS LENSES IN LOW CONTRAST SCENES

A method for identifying and correcting fixed pattern noise includes capturing a focused image and an unfocused image via a variable focus lens. Fixed pattern noise represented in the unfocused image is filtered from the focused image. The unfocused image represents a low-pass filtered component of the focused image; subtracting the unfocused image from the focused image results in a high-pass and fixed pattern noise filtered focused image. Image capture and focus of the variable focus lens are synchronized to remove transitional frames from the image stream.