1. An image processing apparatus connected to a monitoring camera and a display for processing an image input from the monitoring camera, comprising: an image storage unit for storing an image including an input image input from the monitoring camera; a characteristic parameter storage unit for storing a characteristic parameter characterizing a specific image extracted from the input image; a specific image extraction unit, wherein the specific image extraction unit cuts out images having a plurality of predetermined sizes from all parts of the input image stored in the image storage unit, executes character evaluation processing for checking whether or not cut out images have an identical character to the specific image characterized by the characteristic parameter for each cut out image, and extracts the cut out images which are determined to have an identical character to the specific image by the character evaluation processing as an extraction specific image; and a display image generation unit for generating a display image for displaying a whole image of the input image and the extraction specific image on the display, wherein the characteristic parameter storage unit stores a plurality of sets of the characteristic parameter, wherein the specific image extraction unit executes the character evaluation processing for each of the plurality of sets of the characteristic parameter stored in the characteristic parameter storage unit, and when the cut out image is determined to have identical character to the specific image in every executed character evaluation processing, extracts the cut out image as the extraction specific image, wherein the image processing apparatus further comprises a character evaluation processing control unit for setting a priority of the processing in regard to the character evaluation processing for the plurality of sets of the characteristic parameter, wherein the specific image extraction unit executes the character evaluation processing for the plurality of sets of the characteristic parameter based on the priority set by the character evaluation processing control unit, a processing progress information storage unit for storing processing progress information of the character evaluation processing, wherein the character evaluation processing control unit stores identification information of the characteristic parameter indicating that the character evaluation processing is not processed in the processing progress information storage unit when the predetermined limit time elapses before the specific image extraction unit completes the character evaluation processing for all the plurality of sets of the characteristic parameter and the extraction specific image is extracted, reads out the identification information of the characteristic parameter indicating that the character evaluation processing is not processed from the processing progress information storage unit when the predetermined limit time remains after the specific image extraction unit completes the character evaluation processing for all the plurality of sets of the characteristic parameter, and makes the specific image extraction unit execute the character evaluation processing for the characteristic parameter identified by read out identification information.