Minolta Company, Ltd.

Kazuhiro Ueda

Nobuhiro Mishima

Munehiro Nakatani

Eiji Hanada

Shoji Imaizumi

Daisetsu Tohyama

Hiroshi Sugiura

Soh Hirota

An image of a document is divided into a plurality of areas, and a reliability is obtained for each area for a case where an image of the area is used in orientation detection. The reliability is obtained from characteristics of the shape of a histogram generated from image data of the area, as follows. The histogram is divided into a plurality of sections, and an MTF value is calculated for each section by dividing a difference of the max and min values of the section by the sum of the max and min values. A mean value of the MTF values calculated for all of the sections of the histogram is set as the reliability of the area. The orientation detection processing is performed on the area whose reliability is the highest, and an orientation result obtained through the orientation detection processing is judged as the orientation of the image of the document.

Document orientation recognizing device which recognizes orientation of document image

An image processing apparatus is provided with a binarization processing unit separately from a pseudo gradation processing unit that binarizes image data of a document image according to an error diffusion method. The binarization processing unit binarizes the image data of the document image using a threshold that is set higher than a threshold used by the pseudo gradation processing unit, with each threshold representing a different predetermined density level. Histograms showing the density distribution of the document image are generated from the image data binarized by the binarization processing unit. The orientation of the document image is recognized by the histograms.

Image processing apparatus and image forming apparatus which recognize orientation of document image

In an image processing apparatus, an image reading unit reads a document put on a platen glass to generate image data, and a detector in the image reading unit detects offset, tilt angle and document area of the document put on the platen glass. A rotation angle is set based on the image data of a document. The entire document area is determined based on a portion of the document which exists within the image reading area when the document extends beyond the image reading area. The document area can be detected even if a document is not rectangular. For example, a slope of the document is determined based on the detected longest segment. In order to solve the unequal reading pitch, the longest segment is selected in the segments having a slope smaller than a predetermined angle relative to the subscan direction. Then, the image data are corrected according to the above result.

Image processing apparatus

In an image processing apparatus, an image reading unit reads a document put on a platen glass to generate image data, and a detector in the image reading unit detects a tilt angle of the document put on the platen glass. A rotation angle is set based on the image data of a document and the image data is modified according to the rotation angle. The modification is controlled so as not to deteriorate the image quality. For example, the image data is rotated by an angle at which the document is tilted when the document is read, if the detected tilt angle of a document is larger than a predetermined value. The modification of the image data may be controlled according to a characteristic of the image data. For example, the image data is not rotated when the document is decided to include a half-tone image by detecting the attribute of the image data. Preferably, a magnifying power for reading the document is calculated according to the detected tilt angle, and the image data are read again at the magnifying power. Then, the optically magnified image data of the document is rotated by the tilt angle.

Image processing apparatus including image rotator for correcting tilt of the image data

An image processing apparatus capable of outputting high quality image by correcting deviations of respective positions or inclinations of a plurality of sheets of document simultaneously placed on a document base and an image forming apparatus connected to the image processing apparatus and capable of forming a copy with no inclination in respect of paper. Image data with the corrected position or corrected inclination is provided by processing the image signal.

Image processing apparatus and image forming apparatus connected to the

An image forming apparatus records an image on a recording medium after correcting a slant of the image according to a type of document sheet or an operating history of the image forming apparatus. Normally, a slant of the document sheet is corrected by bringing one edge of the sheet in contact with a document scale provided on a document platform. When the sheet is of thin paper or sheets of different sizes are mixed, an image signal obtained by scanning a document image is electrically processed so as to correct a slant of an image to be recorded. When the image signal is electrically processed so as to correct the slant of the image to be recorded, the correction of image slant may be based also on the operating history of the image forming apparatus, for example, the total number of sheets transported, the number of times a paper jam has occurred or the cumulative value of the slant angle of the image.

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Toyokawa, Japan

Kazuhiro Ueda