Method of and apparatus for producing color proof

Claim 1

A method of producing a color proof by converting halftone-dot area percentage data into bit map data by comparison with threshold data, and generating a color proof for a printed color document based on the bit map data with an image output device, comprising the steps of: establishing the threshold data based on a parameter depending on at least one of (1) a recording medium composed of a print sheet, and (2) of printing inks, of the printed color document; converting the halftone-dot area percentage data into the bit map data using the threshold data thus established; and producing the color proof based on said bit map data; wherein said threshold data are established by processing given threshold data with a random number that is established according to standard deviation data which is said parameter and depends on a finish of an image recorded on said recording medium.

Claim 2

A method of producing a color proof by converting halftone-dot area percentage data into bit map data by comparison with threshold data, and generating a color proof for a printed color document based on the bit map data with an image output device, comprising the steps of: establishing the threshold data based on a parameter depending on at least one of (1) a recording medium composed of a print sheet, and (2) of printing inks, of the printed color document; converting the halftone-dot area percentage data into the bit map data using the threshold data thus established; and producing the color proof based on said bit map data; wherein said threshold data are established by processing given threshold data with a random number that is established according to standard deviation data which is said parameter and depends on a finish of an image recorded on said recording medium.

Claim 3

A method of producing a color proof by converting halftone-dot area percentage data into bit map data by comparison with threshold data, and generating a color proof for a printed color document based on the bit map data with an image output device, comprising the steps of: establishing corrective data based on a parameter depending on a print sheet of the printed color document; correcting the bit map data with said corrective data; and producing the color proof based on the bit map data thus corrected wherein said corrective data are established as data of a ratio of an average density of an image recorded on the print sheet to local densities thereof.

Claim 4

A method of producing a color proof by converting halftone-dot area percentage data into bit map data by comparison with threshold data, and generating a color proof for a printed color document based on the bit map data with an image output device, comprising the steps of: establishing corrective data based on a parameter depending on a print sheet of the printed color document; correcting the bit map data with said corrective data; and producing the color proof based on the bit map data thus corrected wherein said corrective data are established as data of a ratio of an average density of an image recorded on the print sheet to local densities thereof.

Claim 5

An apparatus for producing a color proof by converting halftone-dot area percentage data into bit map data by comparison with threshold data, and generating a color proof for a printed color document based on the bit map data with an image output device, comprising: standard deviation data holding means for holding standard deviation data depending on a finish of an image recorded by a recording medium composed of a print sheet and/or printing inks of the printed color document; random number generating means for generating a random number having a standard deviation according to said standard deviation data; threshold data holding means for holding threshold data; and means for selecting standard deviation data, controlling the standard deviation of the random number according to the selected standard deviation data, and correcting the threshold data based on the random number.

Claim 6

An apparatus for producing a color proof by converting halftone-dot area percentage data into bit map data by comparison with threshold data, and generating a color proof for a printed color document based on the bit map data with an image output device, comprising: standard deviation data holding means for holding standard deviation data depending on a finish of an image recorded by a recording medium composed of a print sheet and/or printing inks of the printed color document; random number generating means for generating a random number having a standard deviation according to said standard deviation data; threshold data holding means for holding threshold data; and means for selecting standard deviation data, controlling the standard deviation of the random number according to the selected standard deviation data, and correcting the threshold data based on the random number.

Claim 7

A method of producing a color proof with a color printer which forms an image per pixel based on pixel data of input image data according to a density gradation process, comprising the steps of: referring to threshold matrixes with respect to respective halftone-dot area percentage data generated from an image document for at least three plates including three primaries to convert the halftone-dot area percentage data for the three plates into respective bit map data; simultaneously referring to the bit map data for the at least three plates with respect to respective pixels of the color printer to count area percentages of respective colors (2 n colors when the number of plates is n); processing predetermined colorimetric data of the respective colors with the counted area percentages as a weighting coefficient, thereby calculating average colorimetric data; and using said average colorimetric data as the pixel data of the input image data.

Claim 8

A method of producing a color proof with a color printer which forms an image per pixel based on pixel data of input image data according to a density gradation process, comprising the steps of: referring to threshold matrixes with respect to respective halftone-dot area percentage data generated from an image document for at least three plates including three primaries to convert the halftone-dot area percentage data for the three plates into respective bit map data; simultaneously referring to the bit map data for the at least three plates with respect to respective pixels of the color printer to count area percentages of respective colors (2 n colors when the number of plates is n); processing predetermined colorimetric data of the respective colors with the counted area percentages as a weighting coefficient, thereby calculating average colorimetric data; and using said average colorimetric data as the pixel data of the input image data.

Claim 12

A method of producing a color proof with a color printer which forms an image per pixel based on pixel data of input image data according to a density gradation process, for a printed color document produced by a color printing machine, comprising the steps of: referring to threshold matrixes, having a resolution higher than the resolution of the printed color document, with respect to respective halftone-dot area percentage data generated from an image document for at least three plates including three primaries to convert the halftone-dot area percentage data for the three plates into respective bit map data; simultaneously referring to the bit map data for the at least three plates to count area percentages of respective colors (2 n colors when the number of plates is n) in a given range of the bit map data; processing predetermined colorimetric data of the respective colors with the counted area percentages as a weighting coefficient, thereby calculating first average colorimetric data; processing said first average colorimetric data successively with an anti-aliasing filter in a range greater than the pixels of the color printer to convert the first average colorimetric data into second average colorimetric data corresponding to the pixels of the color printer; and using said second average colorimetric data as the pixel data of the input image data.

Claim 13

A method of producing a color proof with a color printer which forms an image per pixel based on pixel data of input image data according to a density gradation process, for a printed color document produced by a color printing machine, comprising the steps of: referring to threshold matrixes, having a resolution higher than the resolution of the printed color document, with respect to respective halftone-dot area percentage data generated from an image document for at least three plates including three primaries to convert the halftone-dot area percentage data for the three plates into respective bit map data; simultaneously referring to the bit map data for the at least three plates to count area percentages of respective colors (2 n colors when the number of plates is n) in a given range of the bit map data; processing predetermined colorimetric data of the respective colors with the counted area percentages as a weighting coefficient, thereby calculating first average colorimetric data; processing said first average colorimetric data successively with an anti-aliasing filter in a range greater than the pixels of the color printer to convert the first average colorimetric data into second average colorimetric data corresponding to the pixels of the color printer; and using said second average colorimetric data as the pixel data of the input image data.