1. An image processing system for detecting a target object from an image data, comprising: a first extraction processing unit for extracting the target object in the image data, a second extraction processing unit for extracting the target object in the image data, a third extraction processing unit for extracting the target object in the image data, a judgment processing unit for judging whether the target object is in the image data or not, a post-processing unit for extracting the target object in the image data, wherein: S1: a first two-input logical product filter conducts the image processing for calculating logical product from the image data processed with the second extraction processing unit and the image data processed with the third extraction processing unit, S2: the first two-input logical product filter conducts the image processing for calculating logical product from the image data processed with the first extraction processing unit and the image data processed at S1, S3: the first two-input logical product filter conducts the image processing for calculating logical product from the image data processed at S2 and the image data output from the judgment processing unit, and the post-processing unit conducts image processing for the image data processed at S3 and outputs the image data thereby.