JP2859430B2 - Method and apparatus for correcting reference data of printed matter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for correcting reference data of a printed matter, and is useful for evaluating the printing state of a printed matter.

<Related Art> A defective printing state in printing is referred to as “scratch”, and such a printed material is referred to as “scratch paper”. Conventionally, various methods of evaluating printed matter have been proposed to detect this waste paper.

FIG. 3 is a schematic configuration diagram showing a printed matter evaluation apparatus according to the related art together with a part of a printing machine to which the apparatus is applied. In the figure, 1 is a plate cylinder, 2 is a blanket cylinder, 3 is an impression cylinder,
Reference numeral 4 denotes a discharge cylinder, which constitutes a part of a sheet-fed printing press. In such a sheet printing press, the sheet is supplied between the blanket cylinder 2 and the impression cylinder 3 and printed, and is conveyed as a printed material 5 by a delivery chain 6 to a paper stack 7.
Are sequentially laminated.

The evaluation apparatus for the printed matter 5 applied to such a sheet printing press includes a camera unit 8 having a solid-state imaging device that captures, as image data, a printed surface of the sheet supplied to the impression cylinder 3 as image data; An irradiation unit 9 for irradiating the printing surface of the printed matter 5 with light of high illuminance, a rotary encoder 10 attached to the shaft end of the impression cylinder 3 to obtain a rotation synchronization signal,
It has a determination unit 11 to which signals from the camera unit 8 and the rotary encoder 10 are input. Then, in the determination unit 11, the reference image which is the image data of the printing surface of the OK sheet (the printed material 5 which the operator checks the printing state of the printing surface and determines to be good) taken in by the camera unit 8 at the start of printing. Based on the signal from the rotary encoder 10, the data and the judgment image data, which is the image data of the real-time print surface captured by the camera unit 8 at the time of printing, are compared and compared, and the level difference between the two is set to a predetermined allowable set value. The quality of the print state of the printed matter 5 is determined by determining whether the print state is within the range.

On the other hand, a tape inserter 12 is provided above the paper stacking board 7 near the position where the printed matter 5 is stacked. The tape inserters 12 are juxtaposed along the direction of conveyance of the printed matter 5, and when the printing state is determined to be defective (hereinafter referred to as NG), a signal sent from the determination unit 11 causes the printed matter 5 to be determined to be defective. Insert the tape 13.

In the evaluation device as described above, when the camera of the camera unit 8 uses a solid-state imaging device, the image data is, for example, image data of a reference line in a width direction defined in a margin portion which is a grip portion when printing the printed matter 5. The gradation characteristic is adjusted based on the reference data. Specifically, the gain of the amplifier that amplifies the video signal that is the output signal of the camera unit 8 is adjusted so that the level of the reference data corresponding to each pixel is constant.

The reason for adjusting the gradation characteristics in this way is to remove the variation and obtain a video signal of a constant level because the level of the video signal for each pixel, which should be constant, varies for each pixel.

The reason why the level of the video signal varies for each pixel is as follows.

1) The characteristics of each element constituting each pixel of the solid-state imaging device vary.

2) A shading phenomenon occurs in which the illuminance of the illumination light from the illumination unit 9 decreases as it goes to the end in the width direction.

3) Although not directly related to the characteristics of the solid-state imaging device, there is a difference in the amount of reflected light depending on the type of paper as the printed matter 5.

<Problems to be Solved by the Invention> In the adjustment of the gradation characteristics according to the related art as described above, a thin black line such as a register mark is formed around a margin on a reference line that originally provides a white level signal. In the case where the reference data is included, or when dust or the like is attached, the level of the reference data corresponding to the portion is reduced.
There are problems that vertical stripes appear on the display and the evaluation ability of the printed matter 5 is reduced. This is because when the level of the reference data drops, the gain of the amplifier of each pixel of the solid-state imaging device belonging to the vertical line including the pixel corresponding to that part increases, and the level increases only in the vertical line part. It is.

The present invention has been made in view of the above-described problems of the related art, and provides a method of correcting reference data of a printed material that can provide good reference data even when noise is generated due to the wraparound of a black line and adhesion of dust on a reference line. It is intended to provide a device.

<Means for Solving the Problems> According to a configuration of the present invention that achieves the above object, a white level signal of the printed matter in reference image data representing a reference printing state of a printed matter photographed by a camera having a solid-state imaging device. In the case where the gradation characteristic is determined based on the reference data that is the image data on the reference line in the reference line that should be, each pixel adjacent on the reference line of the solid-state imaging device using the reference data If the level difference between the comparison results is equal to or greater than a predetermined value, the average value of the levels of adjacent images on the reference line is calculated. And the reference printing state of the printed matter taken by a camera having a solid-state image sensor. In a reference line in a reference image data, which is a portion to be a white level signal of the printed matter, when determining a gradation characteristic based on reference data which is image data on the reference line, the reference data is acquired. Comparing means for comparing the level between each pixel adjacent on the reference line of the solid-state imaging device; and, as a result of the comparison by the comparing means, when the level difference is equal to or more than a predetermined value, the adjacent images on the reference line are compared. An arithmetic unit that takes an average value of the levels and sets the average value as a level of a pixel whose level difference is equal to or greater than a set value.

<Operation> According to the present invention having the above configuration, when the level difference between adjacent pixels on the reference line is equal to or greater than a set value,
Since the average value of the levels of adjacent pixels on the reference line is taken, even if noise occurs on the reference line, the level of the pixel corresponding to that part drops sharply compared to its neighboring parts. However, reference data representing the original state of the reference portion can be obtained.

<Embodiment> An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a judging unit 21 to which the present embodiment is applied and an external device connected to the judging unit 21, which is applied to the sheet printing press shown in FIG. Therefore, in FIG. 1, the same portions as those in FIG. 3 are denoted by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 1, the determination unit 21 includes an input terminal 22.
a and 22b, a video signal which is an output signal of the camera unit 8 and an impression cylinder 3 which is an output signal of the rotary encoder 10.
Input a rotation position signal indicating the rotation position of
A camera control signal for performing various controls of the camera unit 8 and a speed control signal for controlling the speed of the DC motor are output via the output terminals 23a and 23b. Also,
External device inserter 12, keyboard 24, alarm
Reference numeral 25 is connected to a main bus 27 via an I / O port 26. Thus, the inserter 12 receives the NG signal and
Insert the tape 13 into the box. The keyboard 24 serves as an information input terminal. The alarm 25 notifies a predetermined abnormal state. The color monitor 28 is supplied via the main bus 27, and the display data once read into the display memory 30 via the graphic controller 29 is input via the D / A converter 31 to visualize the display data. is there.

The sample paper memory 32 includes an A / D converter 33 and a comparison circuit 34.
And a reference image memory for storing reference image data, which is a video signal representing a printing state of the OK sheet taken in through the printer. The comparison circuit 34 compares the judgment image data, which is the image data of the printing surface of the print to be evaluated captured via the A / D converter 33, with the reference image data, and compares the level difference between the two for each pixel in a predetermined range. Is determined to be within the allowable set value, and if not, an NG signal is transmitted. The pixels in the predetermined range at this time correspond to one pixel of the CCD which is an image sensor of the camera unit 8 and correspond to a range of about 1 mm square of the printed matter 5. Further, the comparison operation is executed while referring to address data representing the position on the paper surface of the printed matter 5 formed based on the rotational position signal sent from the rotary encoder 10. Thus, the NG address can be stored in the NG position memory 35.

The main CPU 36 performs the following processing in addition to the same processing as the conventional determination unit 11 such as control of each unit of the determination unit 21. That is, reference data, which is image data on a reference line that is a portion to be a white level signal, is extracted from the reference image data stored in the sample paper memory 32, and the reference data of the solid-state imaging device is used by using the reference data. The level between each pixel adjacent on the line is compared, and if the level difference of the comparison result is equal to or larger than the set value, the average value of the levels of adjacent images on the reference line is taken, and this average value is calculated as
The level of the pixel whose level difference is equal to or greater than the set value is set.

That, V _i (i is a natural number) the level of each pixel, when the setting value is L _D, However, comparison and calculation of | V _i −V _i−1 |> L _D or | V _i −V _{i + 1} |> L _D are performed.

As described above, the main CPU 36 of the present embodiment incorporates the comparison means for comparing the levels between adjacent pixels on the reference line, and the arithmetic unit for calculating the average value of the levels of adjacent pixels.

FIG. 2 is a block diagram showing only a portion related to the embodiment of the present invention. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 2, the address generator 37 sends an address signal representing the address of the pixel of the solid-state image sensor of the camera unit 8 (see FIG. 3) based on the output signal of the rotary encoder 10 (see FIG. 3). Is what you do. The shading memory 38 stores the gain value for each pixel of the solid-state imaging device calculated by the main CPU 36 based on the reference data in association with the address signal.

Thus, based on the contents stored in the shading memory 38, the gain value is D / A converted by the D / A converter 39 to adjust the gain of the amplifier 40. As a result, the level of the video signal, which is the output signal of the camera unit 8 (see FIG. 3) supplied to the input terminal 41, is corrected by the amplifier 40 based on the reference data, and the variation in the characteristics of each pixel of the solid-state imaging device is obtained. A good video signal without being affected by
A / D conversion is performed by the D converter 33.

<Effects of the Invention> As described above in detail with the embodiment, according to the present invention, it is possible to obtain reference data representing an original state of a reference portion, and thus noise is generated on a reference line. The level of the output signal of the pixel belonging to the vertical line of the solid-state imaging device including the pixel which does not exist does not increase abnormally. That is, according to the present invention, high-quality reference data can be obtained, which can contribute to appropriate evaluation of printed matter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a printing machine and a printed matter evaluation apparatus to which an embodiment of the present invention is applied, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a judgment unit according to the prior art Is a schematic configuration diagram showing a part of a printing press to which the present invention is applied. In the drawing, 8 is a camera unit, 32 is a sample memory, and 40 is an amplifier.

Claims (2)

(57) [Claims] An image on a reference line, which is a part to be a white level signal of the printed matter, in reference image data representing a reference printing state of a printed matter taken by a camera having a solid-state imaging device. When determining the gradation characteristics based on reference data that is data, the level of each pixel adjacent on a reference line of the solid-state imaging device is compared using the reference data, and the level difference of the comparison result is set. If the value is equal to or greater than the reference value, the average value of the levels of adjacent images on the reference line is taken, and this average value is set as the level of the pixel whose level difference is equal to or greater than the set value. Correction method. 2. An image on a reference line which is to be a white level signal of the printed matter in reference image data representing a reference printing state of the printed matter photographed by a camera having a solid-state imaging device. In the case where the gradation characteristic is determined based on reference data that is data, comparing means for taking in the reference data and comparing levels between adjacent pixels on a reference line of the solid-state imaging device; As a result, if the level difference is equal to or greater than a predetermined value, an average value of the levels of adjacent images on the reference line is calculated, and this average value is set as the level of the pixel whose level difference is equal to or greater than the set value. And a correction device for reference data of a printed material.