1. A specific pattern image recognition apparatus comprising: a binary image generator which binarizes input multi-level color image with regard to specific colors and generates a binary image; a linear conversion processor which performs linear conversion of an examination target image contained in the binary image without changing the size thereof; a degree of correlation calculator which calculates a degree of correlation between the examination target image and the linear-converted image obtained by the linear conversion processor; and a specific pattern determination unit that determines based on the degree of correlation calculated by the degree of correlation calculator whether the examination target image is the specific pattern.