JPH02258345A - Decoloration tester for printed matter - Google Patents

Abstract

PURPOSE:To enable highly accurate testing of decoloration by forming histograms of image density of a reference printed matter and a printed matter to be tested, then, when the difference between the frequencies of a given density is not less than a first decoloration discrimination value, checking the density frequency difference for not only the given density but also the adjacent densities, and discriminating the condition under test as decoloration when the difference is not less than a second decoloration discrimination value. CONSTITUTION:An image on a reference card 1 is picked up by an ITV camera 3, and is subjected to A/D conversion at a converting part 41 in a main body 4 of a tester to be a multivalued image. The multivalued image is stored into a RAM 42, and a density histogram is formed by a calculating part 44. A density histogram for a card 1 to be tested is formed similarly to that for the reference card 1, and the calculating part 44 calculates the difference in frequency between the two density histograms on the basis of each density. When the difference for a given density value (n) is not less than a first decoloration discrimination value alpha, the difference in frequency is calculated for not only the given density value (n) but also the adjacent density values n-1 and n+1, and when the difference is not less than a second decoloration discrimination beta, it is judged that decoloration is present. It is thereby possible to automatize decoloration testing without errors and with high accuracy, through discriminating decoloration from effects of nonuniformity in illustration by a light source 6 or the like.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a printed matter decolorization inspection device for inspecting the decolorization of characters, patterns, and other designs printed on the surface of printed matter such as cards, and particularly to The present invention relates to a printed matter decolorization inspection device that can automatically perform highly accurate decolorization inspection without being affected by unevenness or the like.

(Prior art) In recent years, printed materials such as telephone cards have been magnetically recorded with the number of usable telephones on the back side, and the front side is blank, so that the cards can be used as advertising media for projects. Commonly known as white cards, which have a display printed on them, and cards for reprinting, which have general-purpose characters and patterns printed on the surface, and then reprint advertising displays, are being issued. On the other hand, in order to print a design on the plain surface of such a white card or the surface of a card for reprinting, one card at a time is placed on the printing cylinder on which the stamp surface was made, and the printed surface of the card is aligned with the stamp surface. We are supplying However, in this case, the design may become discolored.

(Problem to be solved by the invention) Therefore, in the past, regarding the card after printing was completed,
An inspector visually inspects each piece for decolorization. However, such an artificial method not only causes simple inspection errors but also requires a large amount of effort and time for inspection. For this reason, recently, when performing a decolorization test, an image of the standard pattern is captured in advance, and this is compared with the image of the pattern on the card to be inspected to find the density difference between the two. It has been proposed to determine that the color is bleached when it is above a certain value. However, with this method, differences in density occur due to uneven lighting during inspection, resulting in a false determination that the color is bleached even though it is not, reducing the reliability of the inspection device. There was an interlude.

The present invention was made to solve the above-mentioned problems, and it clarifies the difference between decolorization and decolorization due to the influence of uneven lighting, etc., and automatically performs error-free and highly accurate decolorization inspection. It is an object of the present invention to provide a printed matter decolorization inspection device that can improve the reliability of the device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a printed matter decolorization inspection device that inspects the decolorization of designs such as characters and patterns printed on the surface of printed matter. and an image input means for capturing an image of the image and an image of the printed matter to be inspected;
A storage means for storing the image captured by the image input means, and a density histogram creation means for creating density histograms for the images of the reference printed matter and the image of the inspected printed material stored in the storage means, respectively. and,
For each density histogram created by the density histogram creation means, the difference in frequency is calculated for each density unit, and it is determined whether the difference is greater than or equal to the first decolorization determination value, and as a result, a certain density value is determined. If the difference is greater than or equal to the first decolorization determination value.

Calculate the difference in frequency including the density values before and after the density value, determine whether the difference is greater than or equal to the second decolorization determination value, and if the result is greater than or equal to the second decolorization determination value. and a decolorization determination means for determining that the color is decolorized.

(Function) In the printed matter decolorization inspection apparatus of the present invention, an image of a reference printed matter is captured in advance by the image input means and is stored in the storage means as a reference image. Next, when performing an inspection, an image of the printed matter to be inspected is captured by the image input means and stored in the storage means. Then, a density histogram of the image of the reference printed matter and the image of the inspected printed material stored in the storage means is created by the density histogram creation means. Next, the decolorization determination means calculates the difference in frequency for each density unit for each density histogram and determines whether the difference is greater than or equal to the first decolorization determination value. If is greater than or equal to the first decolorization determination value, the difference in frequency is calculated including the density values before and after this density value, and it is determined whether the difference is greater than or equal to the second decolorization determination value. As a result, if the difference is less than or equal to the second decolorization determination value, it is determined that there is no decolorization, and if the difference is greater than or equal to the second decolorization determination value, it is determined that decoloration has occurred. In other words, even if the frequency difference at a certain density value is greater than or equal to the first decolorization determination value, if the frequency difference including the density values before and after that density value is not greater than or equal to the second decolorization determination value, it is due to the illumination. Assuming that the variation in density is due to unevenness, it is possible to clearly distinguish between original bleaching and illumination unevenness, thereby making it possible to perform an extremely accurate bleaching inspection.

(Example) First, the concept of the present invention will be explained.

FIG. 4 is a diagram showing an example of a density histogram for an image of a reference printed matter taken in by the image input means, FIG. 5 is a diagram showing an example of a density histogram for an image of a bleached printed matter taken in by the image input means, FIG. 6 is a diagram showing an example of a density histogram for an image of a printed matter taken in by the image input means when affected by uneven illumination or the like. Here, the characteristic of the density histogram when bleached as shown in Fig. 5 is that when compared with the normal density histogram shown in Fig. 4, the frequency value at the location of the density value of the bleached color is extremely reduced. Instead, there is a tendency for the frequency value on the white side to increase dramatically. The reason for this is that printing is usually done in color on a white background, and when the color is bleached, that becomes a white background, resulting in a density value near white. In addition, the characteristics of the density histogram shown in Figure 6 when affected by uneven illumination, etc., are that when compared with the density histogram under normal conditions shown in Figure 4, it is affected in the same way as when bleaching. There is a tendency that the frequency value at a location where the density value is extremely decreased is different from that in that the density value that increases extremely is not on the white side but is near the location where the frequency value is extremely decreased.

Regarding the above trends, if we simply calculate the difference between each density histogram, we can calculate the difference between the density histogram when affected by uneven lighting etc. and the normal density histogram as shown in Figure 6. , similar to the density histogram when bleached as shown in FIG. 5, a large difference appears, making it difficult to distinguish from bleaching. Therefore, in the present invention, the difference in frequency is calculated for each density unit, and if the difference is greater than or equal to the decolorization discrimination value at a certain density value, the difference in frequency is calculated including the density values before and after that density value. , if the difference is greater than or equal to the decolorization determination value different from the above, it is determined that the color is decolorized.

Hereinafter, an embodiment of the present invention based on the above concept will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an example of the overall configuration of a printed matter decolorization inspection apparatus according to the present invention. In FIG. 1, a card 1 such as a telephone card, which is a printed matter on which characters, patterns, and other designs are printed by a printing machine (not shown), is sent to an inspection place by an intermittent feeding machine 2 with the printed side facing up. There is. This intermittent feeding machine 2 outputs two inspection timing signals each time a card 1 is sent to an inspection location, and when an ejection signal 4A to be described later is given, it flips and ejects the card 1 at that time. It has become. On the other hand, the printed matter decolorization inspection apparatus is composed of an ITV camera 3 as an image input means, an inspection apparatus main body 4 consisting of a computer, and a CRT device 5 as a display means. Note that 6 in the figure is a light source such as a lamp for illuminating the vicinity of the inspection location.

Here, the ITV camera 3 captures an image of the card 1.

and for capturing an image of the card 1 to be inspected. Further, the CRT device 5 is for displaying the inspection results of the card 1 to be inspected by the inspection device main body 4. Furthermore, as shown in detail in FIG. 2, the inspection device main body 4 includes an analog/digital (A/D) converter 41, a RAM 42 and a ROM 43 as storage means, and an arithmetic processing section 44.
and an input/output (110) section 45.

Here, the analog/digital (A/D) converter 41
The image captured by the ITV camera 3 is A/D converted to obtain a multivalued image. Further, the RAM 42 stores a multivalued image from the analog/digital (A/D) converter 41.

Furthermore, the input/output (Ilo) section 45 transmits the inspection timing signal 2A and the discharge signal 4A to the intermittent feeding machine 2.
It is used for input and output. On the other hand, R
The OM 43 stores the following functions (a) to (d) as programs, and the arithmetic processing unit 44 performs the arithmetic processing necessary for decolorization according to the programs stored in the ROM 43. be.

(a) A storage function that stores the multivalued image from the analog/digital (A/D) converter 41 in the RAM 42.

(b) A density histogram creation function that creates density histograms for the image of the reference card 1 and the image of the inspected card 1 stored in the RAM 42, respectively.

(c) A first step that calculates the difference in frequency for each density unit for each density histogram created by the density histogram creation function and determines whether the difference is greater than or equal to the first decolorization determination value. Decolorization determination function.

(d) As a result of the determination by the first decolorization determination function, if the difference at a certain density value is greater than or equal to the first decolorization determination value,
The difference in frequency is calculated including the density values before and after the density value, and it is determined whether the difference is greater than or equal to the second decolorization determination value, and if the result is greater than or equal to the decolorization determination value in box 2. A second decolorization determination function that determines that the color is decolorized.

Next, the operation of the printed matter decolorization inspection apparatus configured as above will be explained according to the flowchart shown in FIG.

First, an image of card 1 as a reference is input.

That is, when the reference card 1 comes into the field of view of the ITV camera 3, an image of the card 1 is captured by the ITV camera 3, and this image is converted into A by the analog/digital (A/D) converter 41 of the inspection device main body 4. /D conversion and stored in the RAM 42 as a multivalued image. Then, the arithmetic processing unit 44 performs m
Create a density histogram as shown in Figure 4.

Next, when performing an inspection, a density histogram is created for the card 1 to be inspected that comes within the field of view of the ITV camera 3 in the same manner as for the reference card 1. Next, the arithmetic processing unit 44 calculates the frequency difference K1-1d (n)-d-(n) for each density unit for each density histogram (step S1), and 1 is added to the difference as the first. It is determined whether or not the decolorization determination value α is greater than or equal to the decolorization determination value α (step S2).

As a result, if the difference at a certain density uin is 1 or more than the first decolorization discrimination value α, the difference in frequency including the density values n-1 and n+1 before and after this density value n is 2- I d (n-1) +d (n)+d (n
+1) -d -(n-1)-d -(n)-d -(
n+1) is calculated (step S3), and it is determined whether the difference 2 is greater than or equal to the second decolorization determination value β (step S4).

As a result, if the density histogram of the card to be inspected 1 is as shown in FIG. 4 or FIG. 6, the difference 2 is less than or equal to the second decolorization determination value β, and no decolorization is determined.
6) If the density histogram of the card 1 to be inspected is as shown in FIG. 5, the difference 2 is greater than or equal to the second decolorization determination value β, and it is determined that the card is decolorized (step 37). In other words, even if the frequency difference of 1 is greater than or equal to the first decolorization determination value α at a certain density value n, the density values n−1 before and after that density value n
, n+], if 2 is not equal to or greater than the second decolorization determination value β, it is assumed that this is a change in density due to uneven lighting, etc., and the difference between original decolorization and uneven illumination is clearly distinguished. can be done.

As described above, the print decolorization inspection apparatus of this embodiment creates density histograms of the image of the reference card 1 and the image of the inspected card 1, and calculates the difference in frequency of each density histogram by 1 for each density unit. Then, it is determined whether the difference of 1 is greater than or equal to the first decolorization determination value α, and if the difference of 1 is greater than or equal to the first decolorization determination value α at a certain density value n, the difference of this density value n is 2 is calculated for the difference in frequency including the density values n-1 and n+1 before and after, and it is determined whether or not 2 is greater than or equal to the second decolorization determination value β; If the decolorization determination value β of 2 or more is determined to be decolorization.

Therefore, the inspection for decolorization of characters, patterns, and other designs printed on the surface of the card 1 can be clearly distinguished from the effects of uneven illumination caused by light [6, etc., and can be automatically performed with extremely high accuracy and without errors. This makes it possible to significantly improve the reliability of the inspection device. Furthermore, unlike conventional manual testing methods, it is possible to perform testing extremely easily and without any testing errors.

In the above embodiments, the present invention is applied to cards as printed matter, but the present invention is not limited to this and can be similarly applied to printed matter other than cards.

In addition, in the above embodiment, as the density values near the density value n that is equal to or higher than the first decolorization discrimination value α, the difference in frequency includes the density values n-1 and n+1 immediately before and after the density value n. Although we have described the case where the concentration value n
Two density values n-2, n-1, n+1 . It is also possible to include n+2 and calculate the difference in frequency by 2.

(Effects of the Invention) As explained above, according to the present invention, a density histogram of an image of a reference printed matter and an image of an inspected printed matter is created, and the difference in frequency is calculated for each density unit for each density histogram. It is determined whether the difference is greater than or equal to the first decolorization determination value, and if the difference is greater than or equal to the first decolorization determination value at a certain density value, the frequency difference including the density values before and after this density value is determined. is calculated, and it is determined whether the difference is greater than or equal to the second bleaching discrimination value, and if the difference is greater than or equal to the second bleaching discrimination value, it is determined that the color has been bleached. It is possible to provide a printed matter decolorization inspection device that can clearly distinguish between decolorization and influence, automatically perform error-free and highly accurate decolorization inspection, and improve the reliability of the device.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the overall configuration of a printed matter decolorization inspection apparatus according to the present invention, FIG. 2 is a block diagram showing a detailed configuration example of the inspection apparatus main body 4 in the same embodiment, and FIG. 3 is a diagram showing the operation of the same embodiment. Flowchart for explanation; FIG. 4 is a diagram showing an example of a density histogram for an image of a reference printed matter; FIG.
This figure shows an example of a density histogram for an image of a printed matter that has been bleached, and FIG. 6 is a diagram that shows an example of a density histogram for an image of a printed matter affected by uneven illumination. 1...Card, 2...Intermittent feeding machine, 3...TV
Camera, 4... Inspection device main body, 5... CRT device,
6...Light source, 41...Analog/digital (A/D
) conversion unit, 42...RAM, 43...ROM, 44
... Arithmetic processing section, 45 ... Input/output (I10) section. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] In a printed matter decolorization inspection device that inspects decolorization of designs such as characters and patterns printed on the surface of printed matter, an image for capturing an image of a reference printed matter and an image of a printed matter to be inspected. an input means; a storage means for storing the image captured by the image input means; and a density histogram of each of the image of the reference printed matter and the image of the inspected printed material stored in the storage means. a density histogram creating means to create, and a difference in frequency for each density unit for each density histogram created by the density histogram creating means, and whether or not the difference is greater than or equal to a first decolorization determination value. As a result, if the difference is greater than or equal to the first decolorization determination value at a certain density value, the difference in frequency is calculated including the density values before and after the density value, and the difference is determined as the second decolorization judgment value. A decolorization inspection device for a printed matter, comprising a decolorization determining means that determines whether or not the decolorization value is equal to or higher than a second decolorization determination value, and determines that the color is decolored if the result is equal to or higher than a second decolorization determination value.