Patent ID: 6636630
Filing Date: 2003-10-21
Classification: G06K,H04N

Abstract:
An image-processing apparatus, which deals with an image signal obtained for each pixel by scanning a document and discriminates the pixel as to which area it is located, a character area, a photograph area or a mesh area, characterized by comprising:a first block memory for storing image signals of a first local block consisting of a pixel that is designated as a first target pixel and a plurality of pixels on the periphery of the first target pixel; a maximum/minimum pixel detection section which makes a judgment as to whether the first target pixel is a maximum pixel that gives a maximum density value in the first local block or a minimum pixel that gives a minimum density value therein by using the image signals stored in the first block memory; a maximum/minimum pixel feature-amount calculation section which calculates information as to density changes from the first target pixel to the peripheral pixels within the local block by using the image signals stored in the first block memory; a maximum/minimum pixel classifying section which classifies the first target pixel by using a classifying signal obtained based upon outputs from the maximum/minimum pixel detection section and the maximum/minimum pixel feature-amount calculation section, respectively; a second block memory for storing classifying signals outputted from the maximum/minimum pixel classifying section with respect to a second local block consisting of a pixel that is designated as a second target pixel and a plurality of pixels on the periphery of the second target pixel; a mesh feature-amount calculation section for calculating the amount of feature of the second target pixel by using the classifying signals of the second local block stored in the second block memory; and a mesh judgment section which makes a judgment as to whether or not the second target pixel is a pixel belonging to a mesh area by using the amount of feature calculated by the mesh feature-amount calculation section , wherein said maximum/minimum pixel detection section makes a judgment as to whether the first target pixel is the maximum or minimum pixel in the first local block, based upon the average density value of pixels within the first local block, the result of density comparisons between the density value of the first target pixel and density values of the pixels within the first local block, the sum of density coincident pixels that is a total number of pixels within the first local block having density values coincident with the density value of the first target pixel, and the sum of density differences that is a sum of the absolute values of differences between the density value of the first target pixel and density values of the peripheral pixels within the first local block.