IMAGE PATTERN DETECTING METHOD AND DEVICE

PROBLEM TO BE SOLVED: To track a document having a mark that may be authenticated or duplicated by calculating a reliability level for detecting a prescribed mark in a current area and deciding based on the reliability level whether or not the said mark is detected in the current area. SOLUTION: In a preprocessing step 20, an input image is received in every pixel as the RGB color channel information 21 and the input image data are downsampled and turned into color codes. In a mark detection step 22, the characteristics of received data is compared with the characteristics data on a prescribed (known) mark and the presence or absence of the mark is detected. If the mark is detected in the received data, a matching degree is calculated between the detected mark and a known mark. Then '1' showing a statistical reliability level or plural value are outputted (26) in the step 22. The characteristics data on the mark which are used for the comparison include the color data, outline shape data, size data, luminance characteristics data, etc.