Sharp Kabushiki Kaisha Corporation

Setsuya Kobayashi

Seiji Kohashikawa

Takayuki Amagai

Takeshi Murakami

Takeshi Mutoh

Takahiro Daido

An image-processing apparatus, as well as an image-processing method, is provided with a first inspection circuit which, with respect to density values of pixels within a specific area consisting of a target pixel and pixels in a vicinity thereof in image data for each color component, calculates an average density value, the sum of density differences, that is, the sum of absolute values of differences between the target pixel and the peripheral pixels, and the number the peripheral pixels having the same density value as the target pixel, so that a judgement is made as to whether the target pixel is a maximum value or a minimum value, and also calculates a run-length and the degree of busy from the pixel forming the maximum value or the minimum value. Moreover, based on the run-length and the degree of busy, the second inspection circuit extracts a pixel weight switching signal for each of the color components, and detects the periodicity of meshes of image data by counting pixels not less than the standard value or not more than the standard value based on the pixel weight switching signal within a predetermined counting area. With this arrangement, it becomes possible to carry out the discrimination between character areas and mesh areas as well as the discrimination between black character areas and white character ares with high precision.

Image-processing apparatus and image-processing method

The present invention is directed to an image processing device which is capable of discriminating the classification of a particular area of an image at improved accuracy. In an image processing device according to the present invention, an image input from an image signal input portion is processed in the following steps: a vertical and horizontal complexity calculating circuit determines absolute values Tx and Ty of differential densities between pixels neighboring to each other in vertical and horizontal directions, respectively, within a particular area of the image; a diagonal complexity calculating circuit determines absolute values Rx and Ry of differential densities of pixels neighboring to each other in main diagonal and sub diagonal directions, respectively, within the particular area; a comparator circuit compares sums of absolute values in respective directions and outputs a least sum as a complexity to an area discriminating portion; a difference-comparator portion determines a difference between a maximal value Ma and a least value Mi of densities of pixels of the image data and outputs it as a comparison difference value to the area discriminating portion; and the area discriminating portion discriminates the classification of the image area based on the above-mentioned complexity value and comparison difference value.

Image processing device

An image processing circuit of the present invention includes a succession calculating circuit. In the succession calculating circuit, an average value calculating circuit determines an average value of image data, inputted via line memories, in a specific region, and a multivalue-binary converting circuit converts, in accordance with the average value, the image data into binary data in which the entire image data in the specific region are separated into black pixels and white pixels. A succeeding black pixels calculating circuit calculates the number of succeeding black pixels each in a main scanning direction and in a sub scanning direction, and determines respective maximum values in the main scanning direction and in the sub scanning direction so as to output the respective maximum values as a main scanning direction maximum succession and a sub scanning direction maximum succession. The types of the specific region including the target pixel are discriminated in accordance with the succession, a complexity, and a compared subtracted value so as to carry out an image process in accordance with image types, thus improving discrimination accuracy of image features, used for selecting of an image process which should be carried out, without causing the size of the circuit to increase.

Image processing circuit

A degree of frequency and a comparison difference value are used as an amount of feature that is to be inputted to a discrimination circuit so as to discriminate the kind of regions. The degree of frequency is represented by the smaller of two sums, that is, the sum of absolute values of the density-level difference between pixels adjoining in the line direction of the pixels within the specific region and the sum of absolute values of the density-level difference between pixels adjoining in the direction orthogonal to the line of the pixels, which is obtained by a frequency-degree extracting circuit. Further, the comparison difference value is represented by the comparison difference between a maximum value and a minimum value in the density levels of all pixels within the specified region, which is obtained by the comparison difference circuit. Among a plurality of preset filters, one of the preset filters is selected based upon the amount of feature, and a filtering process is carried out by a filtering-process circuit by using the filter. With this arrangement, discrimination is made as to the kind of region, and a proper filtering process is carried out depending on which region, among the character region, photograph region and halftone-dot region, each focused pixel in an image that has been read belongs to.

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Ikoma-gun, Japan

Setsuya Kobayashi