Yamatoya Company Limited

Susumu Kitazawa

Iwao Numakura

Takashi Numakura

Junichi Naya

A method is provided for the control of a color tone during production of a reproduced color image by tonal conversion of a light quantity of each pixel into a halftone. The method includes setting, at a position between a highlight area and a shadow area in a color original image, a color tone control point, defining adjustment conditions at the color tone control point in terms of dot percent values of desired plural color plates. The method also includes introducing a light quantity at the color tone control point, dot percent values of the plates and desired dot percent values set in advance for highlight areas and shadow areas in the plates into a tonal conversion formula to determine values .gamma. for the plates conversion formulas are provided for converting, into dot percent values, light quantities of all pixels ranging from the highlight areas to the shadow areas. The method also includes subjecting light quantities of individual pixels for the plates to tonal conversion and also controlling color tones of the individual pixels for the plates by using the tonal conversion formulas.

Method for the tonal control or adjustment of reproduced color image and

An original picture having a standard or non-standard picture quality is converted into a halftone picture, which is to be reproduced, on basis of pictorial information. The density information on the individual density characteristic curve is adjusted to the density information on the standard density characteristic curve. The adjusted density information is then processed in such a way that the base density of a desired control point on the original picture and the halftone intensity of a corresponding control point on the halftone picture are correlated in accordance with a specific conversion formula.

Tonal conversion method for pictures

Disclosed herein is a photomechanical apparatus suitable for use in the production of a printing plate, which is adapted to print a halftone picture corresponding to an original continuous-tone picture, on the basis of pictorial information signals obtained by photoelectrically scanning the original continuous-tone picture. The photomechanical apparatus is equipped with a tonal conversion system for converting the pictorial information signals in such a way that the base density of a desired control point on the original continuous-tone picture and the halftone intensity of a corresponding control point on the picture to be reproduced are correlated in accordance with a specific conversion formula.

Photomechanical apparatus

An original continuous-tone picture is converted into a halftone picture, which is to be reproduced, on the basis of pictorial information from the original picture. The information is processed in such a way that the base density of a desired control point on the original picture and the halftone intensity of a corresponding control point on the halftone picture are correlated in accordance with a specific conversion formula.

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Kanagawa, Japan

Susumu Kitazawa