4. A pattern recognition apparatus comprising: a pattern input, unit configured to input a pattern of a recognition object; a feature extraction unit configured to perform feature extraction from the input pattern to generate an input feature vector; a dictionary feature storing unit configured to store a quantized dictionary feature vector of the recognition object; a similarity calculation unit configured to calculate a similarity between the input feature vector and the quantized dictionary feature vector; and a determination unit configured to recognize the recognition object based on the similarity, wherein the dictionary feature storing unit includes: a dictionary input unit configured to input a dictionary pattern of the recognition object; a feature extraction unit configured to perform feature extraction from the input pattern to generate a feature vector; a function generation unit configured to calculate a quantization threshold of each of the quantization number, the function generation unit calculating the quantization threshold of quantization number (n+1) using a quantization threshold of quantization number n (n>=1) and generating a quantization function having a quantization threshold corresponding to quantization number S (S>n); a quantization unit configured to quantize each component of the feature vector of the dictionary pattern using the quantization function to generate an dictionary quantization feature vector having each of the quantized component; and a dictionary feature storing unit configured to store the quantized dictionary feature vector.
9. The apparatus according to claim 4 , wherein the similarity calculation unit calculates the similarity using the quantized dictionary feature vector which comprises a quantization value and a quantization number of each component, and the input feature vector.