JPH0961123A - Watermarked paper making measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and accurately measure a watermarked paper even from an unclear image information by performing digital processing of the image information of a specific visual field of a paper to be inspected with a watermark arranged, and measuring, the projection coordinates, etc., of the short side of the marker. SOLUTION: An image pick-up part 1 picks up the image of a specific visual field of a paper to be inspected by a plurality of CCD cameras of a random shutter according to the arrival signal of a paper to be inspected from a photo sensor part 3. An image processing part 2 converts each picked-up image information to m-bit digital information, and measures and processes a watermark. Namely, a camera angle is set so that the arrangement direction of picked-up image matches the reference direction of the watermark and the image information is subjected to gray-level projection processing. For example, in the case when the marker direction is in parallel with the row direction, the short-side axis coordinates of the marker are obtained by referring to the gray-level information, and the projection coordinates of the short side are measured, thus achieving a stable and accurate measurement even from the marker image information with some defects.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squash marker measuring device which is arranged on a printing paper of squash paper by a squashing method.

[0002]

2. Description of the Related Art Automatically measuring markers arranged by a conventional watermarking method may result in an image with low contrast in a conventional image processing apparatus, and a captured image signal may be a defective image. It was very difficult to make many measurements accurately and at high speed, and many tests were required for the test, and it was difficult to make accurate measurements.

[0003]

As described above, how to measure considerably unclear image information at high speed and accurately is indispensable for producing high-quality printed products such as printing of banknotes. Was desired due to various requirements.

[0004]

In order to achieve the above-mentioned object, a measuring apparatus according to the present invention images a predetermined field of view of a sheet to be inspected in which a skew marker is arranged with a CCD camera and digitally processes the image information. The image processing unit is configured to measure the projected coordinates of the short side of the marker and the coordinates of the outline by the density projection method (hereinafter referred to as one-dimensional measurement). Further, if necessary, the processing range of the image information is narrowed down based on this result, and the long-side projected coordinates are measured. By arranging a plurality of these measuring means, a plurality of measurement points on the sheet to be inspected are simultaneously measured in parallel, and the measurement results are integrated.

[0005]

[Function] In the image information of Squash, uncertain information peculiar to Squash is mixed, but by adopting this projection method, the amount of information peculiar to Squash is large, that is, the non-corresponding part and the amount of information which is considered to be Sukasi It can be detected by the rate. This can be determined even when the scan information is defective in spots, or even when it is divided. If measurement of the long side projection coordinates is necessary, one-dimensional measurement of the same short side projection coordinates is performed in advance, and processing by limiting the range of image information is performed.
Significant reduction in processing time. In addition, since the individual measurement area is very small compared to the papermaking size, in order to grasp the full range of papermaking, it is possible to measure the papermaking over a wide area by calculating between the measurement points.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown schematically in FIG. 1, the measuring apparatus according to the present invention includes an image capturing section 1 capable of simultaneously inputting a plurality of CCD camera signals, an image processing section 2 capable of parallelly image-processing a plurality of image information, and a sample measuring device. It is composed of a photo sensor unit 3 for detection, a display unit 4 for displaying camera image information or a processing screen, and a host computer 5 for controlling each unit and performing an integrated process.

As an example, FIG. 2 shows the required lengths as Xn and Yn in the case of paper making with square markers on four corners in all directions and measuring points at all four corners. In this figure, only the short side projected coordinate value is used for measuring the squash marker. In this figure,
Cameras 1 to 4 are responsible for fields of view A to D. Therefore, camera 1 has X1 and Y1, camera 2 has X2 and Y2.
The camera 3 is responsible for measuring X3 and T3, and the camera 4 is responsible for measuring X4 and Y4. From the same data, X5 and X6 and Y5 and Y6 are calculated by the host computer.

The operation procedure based on FIG. 1 will be described. The paper to be inspected is conveyed to a specified place by a conveyor such as a belt conveyor. When the sheet to be inspected reaches a predetermined place, a photo sensor signal notifies the image pickup unit of the arrival of the inspected item, and a random shutter CCD area camera allows a plurality of CC
The D camera captures a given field of view. In order to sample the marker information better, it is required that the conveyor belt be black or a dark color, and care should be taken not to lift the paper from the conveyor belt.

The image information of each image is digitally converted into m (m is an integer) bits, and a squash marker measurement process is performed in the image calculation unit. In the case of this machine,
The processing time per screen is about 50 ms, so if the measurement cycle is within 100 ms, it will be an image processing unit for simultaneous processing of four screens. For example, if the measurement cycle is 200 ms or more, the image processing unit for single-screen processing will be in time.

FIG. 4 shows a conceptual configuration of the one-image calculation unit. In the figure, it can be considered that the IP is based on SALA announced by Easel Co., Ltd. Koishikawa Co., Ltd. in 1994. The IP has three image input systems, and row delay input is used to construct a two-dimensional local spatial filter. In addition, it is composed of a plurality of work buffer memories, an image input / output I / F, a CPU I / F, and others. The IP has as many as 300 image processing functions, and the desired processing result can be obtained by inputting the image signals in the predetermined space of the buffer memory in a raster pattern.

The image information transferred to the image calculation section is temporarily stored in the buffer memory, and the squash marker measuring operation which is the gist of the present invention is executed. Since the production of Sukasima markers is not uniform for each product even in mass-produced products, the quality of each product varies greatly, but the setting location is fixed, and the basic outline of the paper manufacturing itself is specified. Therefore, the measurement method was devised considering these characteristics.

First, the angle of the CCD camera is set so that the reference direction of the squash marker coincides with the arrangement direction of the captured image. The image calculation unit performs density projection processing on the image information detected in this way. FIG. 4 shows a density distribution chart obtained by executing density projection in the column axis direction when the skew marker direction is parallel to the column direction. By referring to the density information, it can be recognized that the center of the short side of the marker is at Xp (the width of the short side is very small). According to the conventional method of judging from connectivity by this density projection method, if there is a missing part of information, it leads to a detection error.
It can be detected stably. Also, it is possible to know the slope condition of the skew marker from the same distribution condition.

Further, as described above, as another problem of the skew marker, there are many cases where the skew image information is small, that is, the contrast is small. In that case, simply, the density projection means as described above cannot clearly recognize the marker coordinates from the projection data due to uneven illumination and other image information. Therefore, in order to compensate for the defect, it is possible to perform the density projection after performing the differential processing on the original image. The differentiating process is a process of outputting according to the difference between the central pixel and the specific peripheral pixel value in the local space. By this processing, for example, information that changes gently such as uneven illumination and shading can be excluded, and information about the change can be obtained.

Next, referring to FIG. 4, the method of measuring the long side coordinates of the marker will be described. The processing area is limited to Xp ± u before and after the short side coordinates of the marker to determine the row axis coordinates. In this case, since the verification area is narrowed down, depending on the degree, the density projection processing by IP,
In any of the same processing by the CPU, the processing time is short because the verification area is limited, but if the marker information is defective, accurate measurement is difficult. Here, the case where the squash marker direction is the column direction has been described, but similarly in the row direction, first, the short-side projected coordinates are first obtained, and the processing area is limited to obtain the same.

When the direction of the squash marker loses parallelism with the standard, that is, the image information arrangement direction, the density projection distribution on the short side becomes wide. This width is tested and non-parallel,
That is, it can be estimated that the papermaking has an inclination, deformation, or other factors. Since there is no special problem regarding the measurement of the outline of papermaking, there is no particular claim about the measurement method, but the measurement is efficiently combined with the squash marker measurement.

In this way, the data measured by the respective processing systems at a plurality of measurement points are integrated by the host computer, the dimensions between the paper making measurement points are calculated, and the data are utilized for the required processing.

[0018]

As described above, according to the present invention,
Even if the marker image information has some defects, the short mark marker image is captured by a random shutter CCD camera so that the captured image is parallel to the image array direction and the density projection means of the marker is mainly used. You can now measure coordinates. In addition, since multiple processing at a plurality of locations enables accurate measurement of the entire papermaking process, it greatly contributes to eliminating distorted papermaking products and aligning means. This device can perform stable and extremely high-speed measurement by a simple method. With this product, the measurement time is 50
ms.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration example of a single or squash marker measuring device 1 according to the present invention.

FIG. 2 is a diagram showing one measurement example of squash marker papermaking.

FIG. 2 is a diagram illustrating a conceptual configuration example of an image calculation unit.

FIG. 3 is a diagram showing a processing example of a column direction scan marker image.

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[Procedure amendment]

[Submission date] December 25, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is a diagram schematically showing one configuration example of a squash marker measuring device according to the present invention.

FIG. 2 is a diagram showing one measurement example of squash marker papermaking.

FIG. 3 is a diagram illustrating a conceptual configuration example of an image calculation unit.

FIG. 4 is a diagram showing a processing example of a column direction scan marker image.

Claims (1)

[Claims] 1. An image pickup unit 1 having a plurality of inputs of a CCD camera, and an image processing unit 2 for digitally processing the image.
A device including a photo sensor unit 3, a display unit 4, and a host computer 5, and (b) a reference outer shape in which the direction of the squash marker and the arrangement direction of the captured image are the same and are parallel to the reference direction. Set the proper field of view including the line, and (c) measure the coordinates of the short side axis of the squash marker and the coordinates of the outline of the DUT, and (d) or in addition, process image information. The area is narrowed down and the long side axis coordinates and outline line coordinates are measured. (E) By the density projection means, the short side axis coordinates are stable even with specific missing or discontinuous captured image information. (F) In the measurement of the long side axis coordinates, due to the same means and limitation of the processing area, the stability determination effect due to the increase in the ratio of the skew marker information to the density projection value and the decrease in the processing amount place A characteristic of a time-saving effect, and (g) a measurement function measuring device at a plurality of points of an object, which is integrated by a host computer and can be measured between a plurality of measuring points. .