Method of controlling quality of printed images of color printing press and apparatus for controlling quality of printed images

Abstract

The present invention provides a printing image quality management method of a color printing machine and a printing image quality management device of a color printing machine, which can reliably avoid reproduction defects in highlight parts and middle parts and shadow parts caused by state changes of the printing machine. cause poor reproduction. It includes: a measuring mechanism (12) for measuring the solid density and gray balance of the printed color printing image, and a calculation method for calculating the difference between the solid density value and the gray balance value measured by the measuring mechanism (12) and the target value. The mechanism (13), the correction value calculation mechanism (14) that calculates the correction value according to each difference calculated by the calculation mechanism (13), adjusts each of the plurality of ink cartridge keys according to the correction value calculated by the correction value calculation mechanism (14). An ink supply volume adjustment mechanism (15) for individual ink supply volumes.

Description

technical field [0001] The present invention relates to a method for managing the quality of a printed image and an apparatus for managing the quality of a printed image by individually controlling the ink supply amounts of primary color inks of a color printing press. Background technique [0002] As a color printer, there is known a color printer having a plurality of primary colors (representatively, cyan (C), magenta (M), yellow (Y), black ( Bk) A plurality of ink cartridges for printing ink of four colors), and a plurality of ink cartridge keys that can adjust the supply amount of each ink from these ink cartridges and are arranged side by side, and the ink cartridge key is used to adjust the ink supply amount for each ink cartridge key. A plurality of primary color inks are respectively supplied to a plurality of printing plates provided corresponding to a plurality of ink cartridges, and a plurality of primary color images formed by the plurality of primary color inks...

AI Technical Summary

Problems solved by technology

However, the state of the printing machine (such as the viscosity of the ink, etc.) changes due to various factors (such as the room temperature of the printing room, etc.) On the color printed image, the thickness state of dots (so-called dot gain) etc. may change due to the viscosity state of the ink, etc.

In this case, even if the amount of ink is kept approximately constant in the above-mentioned manner, color tone deviation may sometimes occur.

[0008] In terms of solid density management, when the dot gain, etc. changes due to changes in the state of the printing press (ink viscosity, etc.), although it basically maintains The tone of the shadow area (a part with a relatively high dot area ratio) can be managed in the shadow area, but there is a disadvantage that the highlight part (a part with a relatively low dot area ratio) that is easily affected by changes in dot gain etc. part) and the middle part (the part where the dot area ratio is about 50%) tends to shift, causing poor reproduction in the highlight part and the middle part

On the other hand, in the above-mentioned gray management, even if the dot gain or the like changes, the color tone of the highlight and the middle can be basically maintained, and the color tone of the highlight and the middle can be managed, but there are the following disadvantages: , that is, the hue of the shaded portion that is easily affected by changes in dot gain etc. tends to shift, causing poor reproduction in the shaded portion

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