Minolta Company, Ltd.

Minolta Camera Kabushiki Kaisha

Masahiro Kouzaki

Katsuyuki Hirata

Yoshinobu Hada

Kentaro Katori

Yukihiko Okuno

Kentro Katori

A method and an apparatus are provided in which a color of an input image can be reproduced with high accuracy by a small number of colors, and an image quality except the color reproducibility can be optimized. A color of each pixel of the input image is converted into one color selected from a plurality of reproducible colors, and an error due to the conversion is diffused into pixels surrounding the target pixel. In this conversion of the number of colors, a plurality of rules to be selected for a plurality of reproducible colors is prepared. One of the plural rules is selected to be applied for the whole or each part of the input image.

Method and apparatus for converting number of colors and processing image data

An image forming apparatus for forming an image with few defects even when making a copy from a copied image. When forming an image, a standard pattern is formed outside the image forming area in accordance with standard pattern data for color correction. When reading the image together with the standard pattern formed above, the color correction conditions for the image data are modified in accordance with the comparison result between the read standard pattern data and the standard pattern data for color correction. Copying is then performed on a copying paper.

Image forming apparatus which excels in reproducibility of colors, fine lines and gradations even in a copy made from a copied image

Pixel data comprising density data of R, G, and B obtained by reading an original with a CCD image sensor are subjected to shading correction by a shading correction unit, and then converted into color region signals H*, V, and C* in the Munsell color space by a first converter. According to the variations of V, a region discriminator determines whether each pixel data belongs to an edge portion of the original image or whether it belongs to a uniform density region of the original image. A noise removing unit performs noise removal by performing smoothing on color region signals H*, V, and C* of the pixel data which have been determined to belong to uniform density regions. A second converter converts the noise-removed color region signals into pixel data of R, G, and B.

Image forming apparatus having a noise removing unit

An image forming apparatus which forms an image according to image data made up of pixel data on colors of pixel constituting an original image, characterized by comprising a color region discriminator for determining to which color region each pixel data belongs, an image region discriminator for determining whether the pixel data belongs to a uniform density region or whether it belongs to an edge portion, a corrective condition deciding unit for determining MTF corrective conditions for the image data of each color region depending on the discrimination results of both the color region discriminator and the image region discriminator, and an MTF correction unit for performing MTF corrections on the image data according to the MTF corrective conditions determined by the corrective condition deciding unit.

Image forming apparatus having an MTF correction unit

A test pattern comprising a half-tone pattern portion and an edge pattern portion printed according to standard printing data is read by a CCD sensor. A pattern discriminator detects the positions of the half-tone pattern portion and the edge pattern portion. In accordance with a prescribed edge detection criteria using the primary differential data .DELTA.D of density determined by primary differential filters, the CPU determines whether the inputted image data correspond to a uniform density region or whether the inputted image data correspond to an edge portion. If the region discrimination result is different from the result of the pattern detection, the edge detection criteria are changed. The image data is then subjected to MTF correction, and conditions for smoothing or edge emphasizing are altered so that the difference between the corrected image data and the standard printing data remains within a allowable range.

Image forming device and method having MTF correction

The individual pattern of each color of the standard pattern is printed on a copy being made, and when the copy is read by a scanner, the image data of the standard pattern are converted into color region signals in a uniform color space by an HVC converter and a C.multidot.H operation unit. In the case where the saturation of the image data has become lower than the standard saturation of the color region, saturation corrective coefficients are determined by a saturation corrective coefficient calculation unit. After the saturation coefficients have been determined for each color of the standard pattern, the image data of the original are read out, and the saturation corrective coefficients for the color region of the image data are used for saturation correction by a saturation correction processing unit. The image data which have been subjected to the saturation correction are reversely converted into the image data of each color by a reverse HVC converter. According to the reversely converted image data, an image is formed on a copying paper.

Image forming apparatus having a saturation correction unit

In a digital image forming apparatus, when a latent image is formed on a photoconductor by modulating optical intensity of laser beam, the laser beam is emitted in a period of a duty ratio while modulated according to image data, and the image is formed on a sheet of paper. This process is repeated for four colors for a color document. The duty ratio, defined as a ratio of a light-emitting time of a light exposing the photoconductor to a period for exposing a dot, is changed in the same document. For example, the light emission timing pattern is changed between odd and even lines. In another example, the light-emission timings may be changed at least for one of the reproduction colors. The light-emission timing patterns may be provided for each of reproduction colors. The light-emission timing patterns may be changed to have a constant or different screening angle between colors. Image quality of a half-tone image is improved by using such patterns.

Digital image forming apparatus

In a digital image forming apparatus, when a latent image is formed on a photoconductor, a light from a light source is emitted in a period of a duty ratio while modulated according to image data, and the latent image is developed and transferred onto a sheet of paper. The duty ratio, defined as a ratio of a light-emitting time of a light exposing the photoconductor to a period for exposing a dot, is changed in the same document according to dot information on the document such as an edge signal. In the modulation of the optical intensity, the light emission onto the photoconductor is performed with a duty ratio which may be set for each dot. Image portions formed with different duty ratios may exist at the same time in a reproduced image. For example, an edge portion in a document is reproduced at the duty ratio of 100% while a non-edge portion is reproduced at the duty ratio less than 100%.

Digital image forming apparatus and method with variable duty ratio

In an image processing apparatus according to the invention, a first color and a second color are designated. A color conversion matrix is produced based on the designated first and second colors. With the color conversion matrix, the information of the first color included in an input image signal including color information is converted into the second color information.

Image processing apparatus having improved color-reproducibility of

A color image forming apparatus having inputting means for inputting conditions of factors (lighting condition, region, color of eyes, season and date) determining the impression of a color image on an observer. The apparatus further has adjusting means for adjusting at least one of parameters (shading correction data, a reflectance-density conversion characteristic, a UCR/BP characteristic, a masking coefficient, color balance data and .gamma. correction data) of an image processing unit to the input conditions.

Growing community of inventors

Gamagori, Japan

Masahiro Kouzaki