JPH0631904A - Measuring apparatus and method of dot percent - Google Patents

Abstract

PURPOSE:To correctly measure the dot percent of halftone printed matter such as books, newspapers or the like. CONSTITUTION:A measuring part 12 measures the weight before printing and after printing of a first halftone printed matter with an optional dot percent and a second solid printed matter of the area corresponding to the first halftone printed matter. An operating/controlling part 10 operates the dot percent based on the measuring values obtained by the measuring part 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halftone dot area ratio measuring apparatus and method for measuring the halftone dot area ratio in halftone dot printing in books, newspapers and the like.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, an image portion (a portion such as a photograph) in a printed matter such as a book or a newspaper is
A collection of fine dots, that is, dots are printed. In this halftone dot printed area, the larger the halftone dot area, the darker the color appears. The ratio of the area where ink is printed in a unit area is generally called the dot area ratio.

There are cases where it is desired to measure this halftone dot area ratio accurately. For example, there are cases where quality control of printed matter is performed, and where it is desired to formulate the relationship between the color of a certain printed matter and the dot area ratio thereof. Conventionally, as a method for measuring the halftone dot area ratio, there is an optical method using the reflectance of light with respect to a printed matter. Hereinafter, this method will be described.

Here, the reflectance of the paper on which the ink is printed on one side is R1, and the reflectance when the halftone dot area ratio a is printed is R.
a. Ra is considered to be equal to a mixture of the reflectance R1 of the ink-containing portion and the reflectance 1 of the ink-free portion in the ratio of the respective areas. If this is expressed by a mathematical expression, the following expression (1) is obtained. Ra = a × R1 + (1-a) × 1 (1)

Equation (1) is a modification of the equation known as the Murray-Davis equation. R in this equation (1)
By substituting the measured values of a and R1, the halftone dot area ratio a
Is a conventional general method.

[0006]

With the above-mentioned optical method, the area where the ink is printed cannot be accurately measured for the following reasons.

In the conventional method, the paper surface is divided into two parts, that is, a part where ink is printed and a part where ink is not printed, and it is considered that the reflectance is constant in each part. However, this is not strictly true.

That is, the paper is a group of fibers as shown in FIG. 4, and the incident light is repeatedly reflected and refracted inside the paper to be reflected. Therefore, the place where light enters the paper does not always coincide with the place where the light exits, and in the peripheral area of the printed ink, the light that enters the paper from the non-ink part and exits from the ink part, and vice versa. is there. Therefore, the peripheral portion of the ink is blurred. For the above reasons, (1)
The formula does not hold strictly. That is, there is a problem that the conventional halftone dot area ratio measuring method cannot perform accurate measurement. The present invention has been made in view of the above points,
An object of the present invention is to provide a halftone dot area ratio measuring device capable of accurately measuring the halftone dot area ratio.

[0009]

According to the present invention, a first printed matter which is halftone printed with an arbitrary halftone dot area ratio and a solid area which is the same as the area halftone printed on the first printed matter. It is characterized in that the weight of each of the second printed matters to be printed before and after printing is measured, and the halftone dot area ratio is obtained based on the measured values.

[0010]

According to this structure, the first printed matter printed by the halftone dot printing and the second printed matter solid printed by the area corresponding to the halftone printing are printed before printing. Since the dot area ratio is calculated based on the weight after printing, there is no uncertain factor such as optical blur in the peripheral portion of the ink in the optical method, and accurate results can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the halftone dot area ratio measuring apparatus according to the embodiment. As shown in FIG. 1, the halftone dot area ratio measuring device includes an arithmetic control unit 10, a weighing unit 12, a display unit 14, a storage unit 16, a storage unit 18, and a storage unit 20.

The arithmetic control unit 10 controls the entire halftone dot area ratio measuring device and performs an arithmetic operation for obtaining the halftone dot area ratio.
The weighing unit 12 is for measuring the weight (mass or weight) before and after printing of the paper whose halftone dot area ratio is to be measured. The storage unit 16 is for storing the value of the weight Ma of the paper A to be printed (solid printing) measured by the weighing unit 12. The storage unit 18 stores the weight Mb of the paper B to be printed (halftone printing) measured by the weighing unit 12.
For storing the value of. The storage unit 20 stores the weight M of the solid printed paper A measured by the weighing unit 12.
It is for storing the value of a1.

The halftone dot area ratio measuring apparatus according to the present invention measures the weight (mass or weight) of the printed ink and calculates the halftone dot area ratio based on the measured value. On the paper A having the weight Ma, the weight of the paper A when solidly printed with the ink on a predetermined area is Ma1, and the same area as the area solidly printed on the paper A on the paper B having the weight Mb is It is Mb1 when ink is printed with a halftone dot area ratio a. In this case, the weight of the ink on each paper A, B is (Ma1-Ma),
It can be expressed as (Mb1-Mb), and the relationship of the following expression (2) is established between them. a * (Ma1-Ma) = (Mb1-Mb) (2) In this example, Ma1, Ma, Mb1, and Mb are measured, and the halftone dot area ratio a is obtained based on the equation (2). .

Next, the operation of the embodiment will be described with reference to the flow chart shown in FIG. First, the weighing unit 12 measures the weight (Ma) of the paper A (step S1). At this time, the paper A may be a single sheet or a plurality of sheets. The measurement unit 12 outputs the measurement result of the paper A to the calculation control unit 10. The arithmetic control unit 10 stores the measurement result Ma of the paper A in the storage unit 16 (step S2).

Next, the weight of the paper B (M
b) is measured (step S3). At this time, the paper B may be one sheet or plural sheets. Measuring unit 12
Outputs the measurement result of the paper B to the arithmetic control unit 10. The arithmetic control unit 10 stores the measurement result Mb for the paper B in the storage unit 18 (step S4).

Next, solid printing is performed on a predetermined area of the paper A, and the weight of the printed paper A (Ma1)
Is measured by the weighing unit 12 (step S5). At this time, the printing on the paper A may be the entire area or a part thereof. The number of sheets of paper A to be measured is set to match the number of sheets of paper A before printing at the time of measurement in step S1. The measuring unit 12 outputs the measurement result of the printed paper A to the arithmetic control unit 10. Arithmetic control unit 1
In the case of 0, the measurement result Ma1 for the paper A is stored in the storage unit 20 (step S6).

Next, halftone dot printing is performed on the paper B at a constant halftone dot area ratio for a predetermined area, and the weight (Mb1) of the printed paper B is measured by the weighing unit 12 ( Step S7). At this time, the printing on the paper B is the same as the solid printed area on the paper A. Further, the number of sheets of paper B to be measured is made to match the number of sheets of paper A before printing in step S1 at the time of measurement (the number of sheets at the time of measurement in steps S3 and S5). The measuring unit 12 uses the printed paper B.
Is output to the arithmetic and control unit 10.

The arithmetic and control unit 10 includes the Mb1 obtained by the measurement in step S7 and the storage units 16 and 18,
Based on the values of Ma, Ma1 and Mb stored in 20 respectively, the halftone dot area ratio a is calculated and obtained using the above-mentioned equation (2) (step S8). The arithmetic control unit 10 causes the display unit 14 to display the information indicating the obtained halftone dot area ratio a (step S9).

[0019]

As described above, according to the present invention, since the halftone dot area ratio is obtained using the weights of the printed matter before and after printing, the influence of optical blurring in the peripheral portion of the ink is prevented. The halftone dot area ratio can be obtained more accurately than the measurement by the optical method.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a halftone dot area ratio measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining an operation procedure of the embodiment.

FIG. 3 is a diagram for explaining halftone dot printing on a printed matter.

FIG. 4 is a diagram for explaining a method for measuring a dot area ratio by an optical method.

[Explanation of symbols]

10 ... Arithmetic control unit, 12 ... Measuring unit, 14 ... Display unit, 1
6, 18, 20 ... Storage unit.

Claims (2)

[Claims] 1. A first printed matter that is halftone printed at an arbitrary halftone dot area ratio and a second printed matter that is solidly printed on the same area as the halftone dot printed area of the first printed matter. A measuring unit for measuring the weight before and after printing, and an arithmetic control unit for obtaining the halftone dot area ratio based on the measurement value measured by the measuring unit. And a halftone dot area ratio measuring device. 2. A first printed matter which is halftone printed with an arbitrary halftone dot area ratio and a second printed matter which is solidly printed on the same area as the halftone dot printed area of the first printed matter. A method for measuring a halftone dot area ratio, which comprises measuring the weights before and after printing and determining the halftone dot area ratio based on the measured values.