Patent ID: 8422790

Claim:
An image processing apparatus comprising: a conversion unit that converts an input image into a plurality of frequency components; a first quantization threshold calculating unit that calculates a first quantization threshold corresponding to a first frequency component among the plurality of frequency components of the input image converted by the conversion unit, based on a statistic value of the first frequency component; a second quantization threshold calculating unit that calculates a second quantization threshold corresponding to a second frequency component other than the first frequency component among the plurality of frequency components, based on the first quantization threshold calculated by the first quantization threshold calculating unit; and a quantization unit that quantizes the first frequency component and the second frequency component by using the first quantization threshold and the second quantization threshold, respectively, wherein the conversion unit converts a detection target image for a subject to be detected from and a dictionary image into a plurality of frequency components, the dictionary image being intended for use when determining whether the subject is included in the detection target image, the first quantization threshold calculating unit calculates both a first quantization threshold of the detection target image and a first quantization threshold of the dictionary image, the second quantization threshold calculating unit calculates both a second quantization threshold of the detection target image and a second quantization threshold of the dictionary image, and the quantization unit quantizes the detection target image based on the first quantization threshold and the second quantization threshold of the detection target image, and quantizes the dictionary image based on the first quantization threshold and the second quantization threshold of the dictionary image.