1. A method of calculating sharpness of an image using image processing circuitry, the method comprising: using the image processing circuitry, calculating a first sharpness value by applying a first filter to pixels in the image; using the image processing circuitry, calculating a second sharpness value by applying a second filter to the pixels; and using the image processing circuitry, calculating a third sharpness value based on a ratio of the first and second sharpness values, wherein calculating the first sharpness value comprises: calculating a set of values by applying the first filter to the pixels; calculating a number corresponding to how many of the set of values exceed a threshold value; and summing the set of values that exceed the threshold value and dividing the sum of the values that exceed the threshold value by the number.