JPH1153553A - Method and device for acquiring reference image, and method and device for inspecting incorrect collating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a reference image which is suitable for incorrect collating inspection by finding the autocorrelation function of each image which is taken in certain cycles while an image pickup position is shifted and comparing an image to be inspected with the reference image at the time of the largest correlation. SOLUTION: A rotary drum 2 is driven and a quire 1 is sent out of a quire stage. At this time, an image of a specific area P of the sent-out quire is picked up by an image pickup device 4. Further, this image pickup operation is carried out by the blinking of a light source 3 and the driving of the image pickup device 4 based upon timing pulses from a timing signal generating means 8 and images of the contents of different image pickup area P on the quire 1 moving with time are picked up one after another. An image processing means 5, on the other hand, finds an autocorrelation function as a scale for deciding the similarity of each image inputted at each time. Then the area having the largest autocorrelation function in the acquired image is set as the most suitable reference image and stored in a memory. Then an arithmetic processing means 5 compares the picked-up image with the reference image to decide whether or not there is incorrect collating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reference image obtaining method and a reference image obtaining apparatus for obtaining a reference image which serves as a reference for checking a folded document when the printed materials are gathered. The present invention relates to a method and a random inspection apparatus.

[0002]

2. Description of the Related Art In a conventional bookbinding machine, first, each printed matter such as one-fold, two-fold, three-fold, etc. is individually printed by a printing machine, and then each signature is sequentially superimposed on one book. Is obtained. Then, a binding process such as a stapling process is performed, and one book is manufactured.

In such a bookbinding process, if the order of superimposition of the signatures is out of order, or if the same number of signatures is superimposed and superimposed, incorrect signatures are generated. On the other hand, as a device for preventing the occurrence of such irregularities, conventionally, the density of a printed matter is measured by a plurality of photosensors, and the measured density of each point is compared with a reference value registered in advance, so that the printed matter is obtained. In some cases, it is determined whether or not they are the same as predetermined ones.

However, in this apparatus, since the photo sensor detects a very narrow area of the printed matter, any deviation of the printed matter from a predetermined measurement position with respect to the photo sensor causes a large error in the density measurement, and the same printed matter is produced. In some cases, misprints were misjudged, or different printed materials were misjudged as the same printed material.

Further, as another conventional apparatus for preventing the occurrence of incorrect pages, a different position mark is printed for each fold on the back of the quire, and these marks are read by a sensor dedicated to each fold. In some cases, it is determined that there is no mark, and when there is no mark, it is determined that the page is incorrect.

However, in this apparatus, since the detection area of the mark sensor is very narrow, it is not possible to make an accurate determination when a positional shift occurs in a printed material. In addition, when the mark is not accurately formed on the back portion due to a folding failure, it is not possible to accurately judge a wrong page.

On the other hand, there has been proposed a method in which a reference image for inspection is generated from a captured image of a printed material, and the reference image is compared with a captured image of a printed material to be inspected to perform a random inspection.

[0008]

However, in such a conventional inspection method, a reference image is cut out from a fixed area of an image captured by imaging and used. Therefore, there is a problem that the reliability of the inspection performance is lacking.

In addition, when the reference images set for each frame of the bookbinding machine are similar, deterioration of the inspection performance cannot be avoided, and the signature is produced by the rotating drum in the direction of the machine. When being pulled out, the acquired image of the printed matter, which is a signature, is rotated, so that comparison with the reference image cannot be performed in a normal state, and as a result, there is a problem that the reliability of the misjudgment determination is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to obtain a reference image most suitable for the incorrect inspection and avoid similarity of the reference image between adjacent frames.
A reference image acquisition method, a reference image acquisition device, a misalignment inspection method, and a misalignment inspection device that can more reliably prevent misalignment and compensate for the rotation of the inspection target image even when the image to be inspected is rotated. The purpose is to obtain.

[0011]

To achieve the above object,
The reference image acquiring method according to the first aspect of the present invention is to acquire an autocorrelation function of each image captured at a certain period in an image capturing area while shifting the image capturing position while capturing the signature printed matter by an image capturing unit. The image at the time of the maximum correlation based on the obtained auto-correlation function is used as a reference image for inspection of the irregularity.

According to a second aspect of the present invention, there is provided a reference image acquiring apparatus, comprising: an image pickup means for picking up a signature printed matter; The autocorrelation function of each image taken in at the timing of the period is obtained, and the image at the time of the maximum correlation based on the obtained autocorrelation function is used as a reference image for inspection of irregularity.

According to a third aspect of the present invention, there is provided an inspection apparatus for inspecting a facsimile, which has an image pickup means for picking up an image of a folded printed matter. At the timing of, the autocorrelation function is obtained for each image, and the reference image at the time of maximum correlation based on the obtained autocorrelation function is compared with the captured image of the printed matter to be inspected for the irregularity inspection. It is like that.

According to a fourth aspect of the present invention, there is provided a reference image acquiring method, comprising:
An image is taken for each frame, an autocorrelation function of each image captured at a certain period of time in the imaging area is obtained while shifting the imaging position, and the image at the time of the maximum correlation based on the obtained autocorrelation function is used for inspection of the irregularity. And a cross-correlation value of each of the reference images obtained for each specific frame and each frame adjacent thereto is determined. When the obtained cross-correlation value exceeds a set level, the reference of the specific frame is determined. By re-acquiring the image, the cross-correlation value between the adjacent frame and the reference image is set to be equal to or less than the set level, and is used as the reference image of the specific frame.

Further, in the reference image acquiring method according to the present invention, if the cross-correlation value does not become lower than the set level even when the reference image of the specific frame is retaken, the reference image of the adjacent frame is obtained. And the cross-correlation value of the specific frame with the reference image is set to be equal to or less than the set level, and is used as the reference image of the specific frame.

According to a sixth aspect of the present invention, there is provided an apparatus for inspecting an incorrectly-ordered sheet, comprising: a plurality of image pickup means for picking up a printed copy of each signature of each book of the bookbinding machine; Image processing means for obtaining an autocorrelation function of each image captured at a certain period of time in the area, and using the image at the time of maximum correlation based on the obtained autocorrelation function as a reference image for incorrect inspection, The cross-correlation value of each reference image obtained for each frame and the frame adjacent thereto is obtained, and when the obtained cross-correlation value exceeds a set level, the reference image of the specific frame is retaken. The cross-correlation value between the reference image of the adjacent frame and the reference image is set to be equal to or less than the set level, and the reference image of the specific frame is used. One in which the.

Further, in the inspection apparatus according to the present invention, if the cross-correlation value does not become lower than the set level even when the reference image of the specific frame is re-taken, the reference image of the adjacent frame is recalled. In this case, the cross-correlation value between the specific frame and the reference image is set to be equal to or less than the set level, and is used as the reference image of the specific frame.

[0018] In the inspection method according to the present invention, a plurality of reference image groups obtained by rotating the reference image for a specific inspection of a specific page are obtained, and the reference image group and the inspection object are imaged. An image is compared with an image, and the one with the highest degree of coincidence is used as a final comparison result to perform a random inspection.

[0019] The inspection apparatus according to the invention of claim 9 has an image pickup means for picking up an image of the folded printed material, and the image processing means is provided with a plurality of sheets obtained by rotating a reference image for inspection of a particular signature. The reference image group is obtained, the reference image group is compared with the captured image of the inspection target, and the one with the highest degree of coincidence is subjected to a random inspection as a final comparison result. is there.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing a bookbinding machine having a reference image acquisition device and a random page inspection device according to the present invention. Here, only one frame is shown, but a plurality of frames (for example, 12 to 36 frames) are arranged side by side. Has been established. In the figure,
Reference numeral 1 denotes a signature placed on a signature stage corresponding to each piece. These signatures are printed with different contents from each other and are signatures. Reference numeral 2 denotes a rotating drum that sends out the signatures 1 from the signature stage one by one to the collating machine side. The signatures sent out by the rotating drums arranged in the horizontal direction for each frame are respectively conveyed by, for example, a conveyance mechanism (not shown), and the signatures can be stacked during the conveyance. After the stacking, a binding process by a stable is performed, and assembled into one book.

Reference numeral 3 denotes a light source for illuminating a signature such as a lamp disposed opposite to each rotary drum 2 for each signature stage, and 4 denotes a CCD camera for imaging the signature 1 illuminated by the light source 3. And the like. Reference numeral 5 denotes an image processing device which is connected to the imaging device 4 and captures and processes the captured image. The image processing device 5 calculates an autocorrelation function of the captured image at a predetermined period for each frame, and obtains the obtained autocorrelation function. It functions so that the image at the time of the maximum correlation based on the relationship is used as the reference image for the incorrect inspection. Further, the image processing apparatus has a function of comparing the acquired reference image with the image to be inspected to perform the inspection of the irregularity such as the determination of the existence of the irregularity.

An encoder for detecting a rotation speed and a rotation position of the rotary shaft 6 electrically, magnetically or optically and outputting a pulse around a rotary shaft 6 common to the rotary drum 2 for each frame. 7 are provided. Numeral 8 is a timing signal generating means for generating a lighting timing of the light source 3, a driving timing (imaging timing) of the CCD camera, and an image processing timing by the image processing means 5 based on the output pulse of the encoder 7.

Although not shown, the image processing means 5
Has a readable and writable memory for independently storing the reference image and the inspection object image, a misalignment inspection circuit for comparing these reference image and the inspection object, and performing a misalignment determination. A microprocessor (not shown) performs various processing of image data by the image processing means.
It is executed according to a setting program under control.

Next, the operation will be described. First, the acquisition of the reference image used for the irregularity inspection will be described for one frame in FIG. First, the rotary drum 2 of the bookbinding machine is driven to send out the signature 1 from the signature stage. At this time, the imaging device 4 images a predetermined area P as shown in FIG. This imaging is performed by blinking the light source 3 according to the timing pulse from the timing signal generating means 8 and driving the imaging device 4, and the contents of the different imaging areas P on the signature 1 moving with the passage of time. Are (a), (b), (c),... (N) in FIG.
As shown in FIG. The timing signal at this time is a Z-phase timing pulse that determines an imaging area P in a fixed visual field width W as shown in FIG. It consists of an A-phase timing pulse having a constant period. Therefore, the image is taken in every time at the timing of the A-phase timing pulses a, b, c,... N in FIG. 3, and as a result, the printed content of the signature is changed to the field width W as shown in FIG. Can be taken into the image processing means 5 over the entire length.

On the other hand, the image processing means 5 obtains an autocorrelation function as a measure of similarity determination of each image taken every time. The correlation level obtained based on such an autocorrelation function is based on the imaging area shown in FIGS. 5A, 5C, and 5D and the respective timing pulses a, b, c,.
.. N are graphs that change as shown in FIG. 5B, for example. Therefore, the timing signal when the correlation level reaches the maximum (extreme value) in this change is used as the image capture timing, that is, the most characteristic (high autocorrelation) region in the acquired image is most frequently used for the random inspection. It is set as a suitable reference image and stored in the memory.

Next, the signature to be inspected is sent out by driving the rotary drum 2 again, and the contents of the print on the signature are imaged by the imaging device 4 in the same manner as described above. The arithmetic processing unit 5 compares the captured image with the reference image, and if there is a match, it is determined that there is no mismatch, and if there is no match, it is determined that there is a mismatch, and, for example, a process of discarding this outside the gathering path is executed.

On the other hand, as described above, on the signature stage for each frame, signatures 1 of different types of printed matter are provided side by side, and the similarity of each reference image acquired for each adjacent frame is checked. Even if it is high, an incorrect inspection result may be obtained. In such a case, the reference images acquired between adjacent frames are exchanged to check their similarity, and if they are similar, the acquisition timing of one of the reference images is set to the reference timing acquired as described above. The obtained reference image is shifted to a new second candidate point shifted from the first candidate point of the image, and the obtained reference image is used as a new reference image. This is compared with another reference image of an adjacent frame. While sequentially shifting the above candidate points,
Further, another reference image is obtained, and when there is no similarity, this is determined as a reference image, acquired and stored in a memory.

For example, adjacent frames are (n-1) frames, n
A cross-correlation is taken between these as a frame and an (n + 1) frame, and when a correlation value equal to or higher than a specific level is obtained, the candidate points are changed from the first candidate point * 1 to the second candidate point * shown in FIG. 2, the reference image of the second candidate point * 2 is obtained, and the cross-correlation is checked again by the above method. If the cross-correlation value is still equal to or higher than the specific level, another third candidate point is set. The candidate point from the third candidate point may be a predetermined position where the timing pulse shown in FIG. 5 is shifted one by one, or another extreme point different from the above in the curve of the correlation level shown in FIG. Is arbitrary.

In this case, if the reference image cannot be determined for all the selected candidate points a, b, c,... N, the right to change the reference image is given to another adjacent frame. In the same way, in the same manner as described above, the comparison with the reference image obtained by another frame and the determination of the similarity are repeated, and the optimum reference image is determined.

In the course of being sent out from the signature stage by the rotary drum 2, the signatures gathered by the bookbinding machine may be slightly deflected in the forward and reverse horizontal directions and guided. Therefore, the captured image to be inspected is also inclined, and when compared with the acquired reference image, the inspection accuracy of the irregularity is significantly deteriorated,
As a result, the reliability of the results of the incorrect inspection is lacking.

Therefore, in the present invention, based on the reference image set as described above or the reference image Q1 set by other methods, a minute rotation (horizontal rotation) is given to the forward and reverse directions to Plural as shown in Fig. 6 (two here)
Are prepared, and these are referred to as reference images Q2 and Q2.
As 3, the intended inspection of the signature can be performed in the same manner as described above by sequentially comparing the image with the inspection target image of the signature which is deflected in the horizontal direction and sent as described above. These rotated reference images Q2 and Q3 can be easily obtained by the image processing by the image processing means 5.

The reference image Q2 thus rotated
From Q3, as shown in FIG. 7, a necessary comparison region R is cut out corresponding to the captured image of the signature to be inspected for the irregularity,
That is, the edge part of the rotated reference image Q3 is cut out, and the comparison region R is extracted. Therefore, each reference image Q
2 and Q3 need to be larger than the captured image to be compared for the random inspection.

In this way, 2n rotated reference images obtained by rotating the reference image in the forward and reverse directions are produced, and these are combined with the original reference image (2n + 1).
The entire reference image group can be compared with the captured image to be inspected, and the image with the highest degree of coincidence can be determined as the final result.

[0034]

As described above, according to the present invention, the signature printed matter is imaged by the imaging means, and the autocorrelation function of each image captured at a constant period in the imaging area while shifting the imaging position is obtained. The obtained image at the time of the maximum correlation based on the obtained autocorrelation function is used as the reference image for the incorrect inspection, so only the reference image size is determined in advance, and the highest autocorrelation among the captured images is obtained. By using the region as the reference image, it is possible to obtain an effect that a high-precision inspection of each frame can be performed at the time of collating work using the region.

According to the present invention, a cross-correlation value of each of the reference images obtained for a specific frame and a frame adjacent thereto is obtained, and when the obtained cross-correlation value exceeds a set level, By re-taking the reference image of the specific frame, the cross-correlation value between the reference image of the adjacent frame and the reference image is reduced to the set level or less, and the reference image of the specific frame is used. An effect is obtained that erroneous detection of incorrect pages due to similar images can be avoided.

Further, according to the present invention, a plurality of reference image groups obtained by rotating the reference image for a particular page inspection are obtained from the reference image for inspection of a particular page, and these reference image groups are compared with the captured image of the inspection object. Because the result of the maximum matching is obtained as the final comparison result, the misalignment inspection is performed, so even if the image of the inspection target that is captured is deflected in the horizontal direction, it can be compared with the reference image. Can be carried out properly, and the accuracy degradation of the incorrect inspection result can be reliably avoided.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a bookbinding machine having a reference image acquisition device and a random page inspection device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship between an imaging area and a signature according to the present invention.

FIG. 3 shows a timing pulse generator Z in FIG.
FIG. 4 is a timing chart showing phase and A-phase output pulses.

FIG. 4 is an explanatory diagram showing a relationship between a signature and a visual field according to the present invention.

FIG. 5 is an explanatory diagram showing a relationship between a capture timing of a captured image and an autocorrelation level in the present invention.

FIG. 6 is an explanatory diagram showing a rotation direction of a reference image according to the present invention.

FIG. 7 is an explanatory diagram showing a method of cutting out a comparison area from a rotated reference image according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 signature 4 imaging means 5 image processing means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Kishi, Inventor Hiroshi Kojima 1-15-1 Kaga, Itabashi-ku, Tokyo (72) Inventor Hiroshi Kojima 1-1-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd.

Claims (9)

[Claims] 1. An image of a signature printed matter is taken by an image pickup means, and an autocorrelation function of each image taken at a certain period timing in an image pickup area while shifting an image pickup position is obtained.
A method of acquiring a reference image, wherein the image at the time of maximum correlation based on the obtained autocorrelation function is used as a reference image for inspection of irregularity. 2. An image pickup means for picking up an image of a printed product, and an autocorrelation function of each image taken at a constant period in an image pickup area while shifting the image pickup position by the image pickup means. A reference image acquisition device comprising: an image processing unit that uses the image at the time of the maximum correlation based on the function as a reference image for inspection of a page. 3. An image pickup means for picking up an image of a printed product, and an autocorrelation function of each image taken at a constant period in an image pickup area while shifting the image pickup position by the image pickup means. An apparatus for inspecting a misaligned page, comprising: an image processing means for performing an incorrect page inspection by comparing a reference image at the time of maximum correlation based on a function with a captured image of a printed matter to be inspected. 4. A signature printed matter is imaged for each frame by a plurality of imaging means, and an autocorrelation function of each image captured at a certain period timing in an imaging area while shifting an imaging position is obtained. The image at the time of the maximum correlation based on the autocorrelation function is used as a reference image for inspection of irregularity, a cross-correlation value of each of the reference images obtained for a specific frame and a frame adjacent thereto is obtained, and the obtained cross-correlation value is obtained. When the correlation value exceeds the set level, the cross-correlation value between the reference image of the adjacent frame and the reference image of the adjacent frame is reduced to the set level or less by re-taking the reference image of the specific frame, and the reference image of the specific frame is set. A reference image acquisition method characterized by the above-mentioned. 5. When the cross-correlation value does not become lower than a set level even when the reference image of the specific frame is re-taken, the reference image of the adjacent frame is re-taken, and The method according to claim 4, wherein a correlation value is set to be equal to or less than the set level to be a reference image of the specific frame. 6. A plurality of image pickup means for picking up a signature printed matter for each frame of the bookbinding machine, and each image taken at a constant period in an image pickup area while shifting the image pickup position by the image pickup means. And an image processing means for setting the image at the time of the maximum correlation based on the obtained autocorrelation function as a reference image for inspection of irregularity, provided for each specific frame and each frame adjacent thereto. The cross-correlation value of each of the reference images is obtained, and when the obtained cross-correlation value exceeds a set level, the cross-correlation value of the adjacent frame with the reference image of the adjacent frame is obtained by re-taking the reference image of the specific frame. An incorrect page inspection apparatus, wherein a reference image of the specific frame is set to be lower than the set level, and the reference image is compared with a captured image of an inspection target to perform an incorrect page inspection. 7. When the cross-correlation value does not become lower than the set level even when the reference image of the specific frame is re-taken, the reference image of the adjacent frame is re-taken and the cross-correlation value of the reference image of the specific frame is re-taken. 7. The apparatus according to claim 6, wherein a correlation value is set to be equal to or less than the set level and is used as a reference image of the specific piece. 8. A plurality of reference image groups obtained by rotating the reference image for inspection of a specific irregularity are obtained, and the reference image group is compared with a captured image of an inspection object to obtain a maximum matching degree. This is a method of inspecting the incorrect pages as a final comparison result. 9. An image pickup means for picking up a signature printed matter, a plurality of reference image groups obtained by rotating a reference image for inspection of a specific irregularity, and a reference image group and a picked-up image of an inspection object. And an image processing means for inspecting the page with the highest degree of coincidence as a final comparison result.