JPH04119480A - System for deciding effective four sides of rectangular paper sheets - Google Patents

Abstract

PURPOSE:To shorten time for processing by calculating a position data showing the edges of a rectangular paper sheet from a binary pixel data and defining respective linear parts regulated by the most frequent values of this position data as the effective four sides of the rectangular paper sheet. CONSTITUTION:The position data (X and Y coordinates) showing the edges of the paper sheet is calculated from the binary pixel data. Next, the most frequent values of this position data are calculated for the respective sides of the rectangular paper sheet, and the respective linear parts regulated by these most frequent values are defined as the effective four sides of the rectangular paper sheet. In this case, as the range of search for calculating the position data, only the range of picture elements from the binary data '0' of the background part to the binary data '1' of the paper sheet part is enough. Thus, time for processing can be shortened.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for determining the effective four sides of rectangular paper sheets, the purpose of this method is to reduce the amount of data used to calculate the four effective sides and shorten the processing time. In an image processing method that calculates the four effective sides of an input grayscale image, the pixels of the input grayscale image are converted into binary pixel data that distinguishes between a background part and a sheet part, and this binary pixel data is Based on this, the position data indicating the edge of the paper sheet portion is determined.Furthermore, the mode of this position data is determined for each side of the paper sheet, and the mode of the straight line portion defined by this mode is calculated. It has a configuration in which each of the four sides is the effective four sides.

[Industrial application field]

The present invention relates to an image processing method for identifying the four sides of rectangular paper sheets, such as banknotes, check certificates, bonds, lottery ticket postcards, and identification cards.

[Conventional technology]

Generally, rectangular paper sheets such as banknotes are counterfeit tickets.

When checking whether a ticket is torn or soiled, it is first necessary to determine the outer shape of the rectangular paper sheet, that is, the four effective sides.

Conventionally, the four effective sides of a rectangular paper sheet have been determined using the procedure shown in FIG.

That is, (1) rectangular paper sheets are put into the input section and moved along the conveyance path.

■'Optical sensor installed at a predetermined position on the conveyance path.

Using various sensors such as a thickness sensor, a grayscale image representing the pattern and external shape of a rectangular paper sheet is obtained. Note that since the rectangular paper sheets conveyed to the positions of the various sensors are tilted by 1 to 3 degrees, the grayscale images are also tilted.

■'Convert each pixel of the grayscale image into a grayscale signal, binary data, etc. and store it in the image memory.

■' A regression line is obtained by statistical processing such as the method of least squares on the binary data, and various image processing such as skew correction and end point correction is performed to create an entire image of the rectangular paper sheet without the skew. Align the state.

■'For the binary data after the sorting process, the minimum 2
A regression line corresponding to each side of the rectangular paper sheet is determined by performing statistical processing such as multiplication.

■' Each of these regression lines is determined as the four effective sides of the rectangular paper sheet.

The external shape of rectangular paper sheets was determined using these steps.

[Problem to be solved by the invention]

As mentioned above, the conventional method for identifying the four sides of rectangular paper sheets involves performing statistical processing such as the least squares method on the data read out from the image memory. There is a problem in that the processing time is long because many image data (in some cases, all image data) are handled.

Therefore, in the present invention, instead of statistical processing such as the least squares method on the binary pixel data read from the image memory, position data (X coordinate .

X coordinate), then find the mode of this position data for each side, and set each of the straight line parts defined by this mode as the four effective sides of the rectangular paper sheet. The purpose of this method is to reduce the amount of data required to calculate four effective sides and shorten processing time.

[Means to solve the problem]

FIG. 1 shows the basic procedure of image processing for determining the four effective sides of a rectangular paper sheet from a grayscale image according to the present invention.

That is, (1) Obtain a grayscale image representing the pattern, outer shape, etc. of a rectangular paper sheet using various sensors such as an optical sensor and a thickness sensor.

(2) Each pixel data of the grayscale image is converted into binary pixel data that distinguishes the background portion and the rectangular sheet portion, and is stored in the image memory. Note that the XYv mark and each direction of A, B, C, and D are set for this binary image as shown in the figure.

(2) Based on this binary pixel data, position data indicating the edge of the sheet portion is determined. For example, A, B, C, D
Examine the binary pixel data in the image memory for each direction of Search. Here, if there is no binary pixel data of "1", such as in the first column (X=1), the position data is set to "0".

(2) Find the mode of the position data for each side of the rectangular paper sheet. For example, the mode obtained by searching in six directions is rY=3'', and the mode obtained by searching in direction B is ``x-2''.
It is.

■Estimate and confirm each of the straight line portions represented by this mode as the four effective sides of the rectangular paper sheet.

Using this processing procedure, the four effective sides of a rectangular paper sheet are determined from a gray-scale image.

Incidentally, among the above steps, ① to ② are processes unique to the present invention.

Furthermore, the tilt of rectangular paper sheets that occurs in the conveyance path may be corrected by various types of image processing as shown in Fig. 5, or a position adjustment mechanism may be provided in the conveyance path. Mechanical correction may also be performed.

[Effect]

In the present invention, position data indicating the edge of a paper sheet portion is obtained based on binary pixel data of an image of a rectangular paper sheet, and the most effective value of the rectangular paper sheet is determined from the most frequent value of this position data. The four sides are fixed. Here, the search range for obtaining the position data is the binary data of the background part "
A pixel range extending from "0" to the binary data "1" of the sheet portion is sufficient. Furthermore, when a plurality of mode values appear, the minimum value is used for the A and B directions, and the maximum value is used for the C and D directions to ensure data reliability.

〔Example〕

The present invention will be described in detail with reference to FIGS. 2 to 4.

Fig. 2 is an explanatory diagram showing the structure (30x128) of binary pixel data stored in the image memory, where the area where there is no rectangular paper sheet is "0" and the area where there is rectangular paper sheet. is "1".

Then, processing to check the change of this binary data from "0" to "1" will be executed, but the content of the image processing for the rectangular paper sheet after the four effective sides have been determined. Accuracy varies. Therefore, depending on the content of the image processing after this determination, it may not be necessary to determine the four effective sides with high accuracy by using the binary data on the pixel memory as is.

An embodiment corresponding to such a case will be described below. First, as shown in the dotted line in the figure, binary pixel data on the pixel memory is divided into m dots vertically and n dots horizontally (here, m=2,
(n-4) area, and then simply add the binary data therein for each area to sequentially bundle area data (15×32).

As shown in Fig. 3, this area data is "8" in the area where the paper sheet exists without any damage.
The value is "0" in areas where there are no paper sheets, and the value is between "O" and "8" in areas where there are edges or defects of paper sheets.

Then, when viewing this area data from each direction of A, B, C, and D, position data (X coordinate and Y coordinate) indicating the position where the value is "8" is first added to each of the rectangular paper sheets. The sides are determined, and the mode value of this position data is determined for each side, and the four effective sides of the rectangular paper sheet are determined from the mode value.

Figure 4 shows the processing procedure at this time, where ■'X is set to "1".
Then, set the search direction to rAJ and store the Y coordinate where the value becomes "8" for the first time, and proceed to the next step.

Note that if there is no area with a value of "8", store [Oj].

■' Determine whether or not X=32. If r YBSJ, proceed to step ■'; if "NO," proceed to step ■'.

(2) Determine whether or not the process of storing the Y coordinate in the A-direction force C direction has been completed. If r YBSJ, proceed to step (2); if r NOJ, proceed to step (2).

■Add "1" to 'X' and return to step ■'.

■ Set 'X' to "1" and search direction to "C" and return to step ■'.

(2) Store the X coordinate where 'Y is set to "1" and the search direction is set to "1B" and the value becomes "8" for the first time, and proceed to the next step.

Note that when there is no area with a value of "8", "0" is stored.

■' It is determined whether Y=15, and if r YBSJ, proceed to step ■'; if "NO", proceed to step 0'.

(2) Determine whether the process of storing the X coordinates in both the B direction and the D direction has been completed. If rY8SJ, proceed to step 0', and if "NO", proceed to step (2).

Add "1" to 0'Y and return to step ■'.

■ Set Y to "1" and the search direction to "D" and return to step ■'.

@' The mode of the coordinates where "8" first appears in each of the A, B, C, and D directions, that is, in the direction, Y=
2. In direction B, X=2. In the C direction, Y=13. In the D direction, x-29 is determined, and the straight line portion specified by this mode is defined as the four effective sides of the rectangular paper sheet.

It becomes.

In the above embodiment, the processing speed is increased by converting 3840 (30×12g) pixel data into 480 (15×32) area data and performing the above processing on this area data. There is.

Furthermore, instead of converting the pixel data stored in the image memory into the area data, pixel data immediately after binarization may be converted into the area data.

〔Effect of the invention〕

The present invention obtains position data (X coordinate 4ti, Y coordinate) indicating the edge of a paper sheet portion based on binary pixel data, and then calculates the mode of this position data for the rectangular paper sheet. This is calculated for each side, and each of the straight line parts defined by this mode is taken as the four effective sides of the rectangular paper sheet, so the amount of data used to calculate the four effective sides is reduced and the processing time is reduced. It is possible to shorten the time.

[Brief explanation of the drawing]

Fig. 1 shows the basic procedure for determining the effective four sides of a rectangular paper sheet according to the present invention, Fig. 2 is an explanatory diagram showing binary pixel data stored in the image memory, and Fig. 3 shows area data. FIG. 4 is an explanatory diagram showing an embodiment of the present invention using area data, and FIG. 5 is a conventional procedure for determining the four effective sides of a rectangular paper sheet. In Fig. 1, ■... Step of detecting position data indicating the edge of rectangular paper sheet ■... Step of finding the mode of position data ■...
・Step to determine the four effective sides

Claims (3)

[Claims] (1) In an image processing method that calculates the four effective sides of an input grayscale image of a rectangular paper sheet, the pixels of the input grayscale image are converted into binary pixel data that distinguishes the background part and the paper sheet part. Then, based on this binary pixel data, find position data indicating the edge of the paper sheet portion, and further find the mode of this position data for each side of the paper sheet, and calculate the mode of this position data for each side of the paper sheet. A method for determining four effective sides of a rectangular paper sheet, characterized in that each of the straight line portions defined by the above four sides is defined as the four effective sides. (2) In an image processing method that calculates the four effective sides of a rectangular paper sheet from an input grayscale image, each pixel of the input grayscale image is divided into a background part and a paper sheet part. Convert this input grayscale image to data, m×n (m and n are both positive integers)
A region consisting of pixels is divided into multiple regions lined up in a grid pattern, and region data is calculated by adding all the binary pixel data of this region. When looking at the change in the area data from the background area to the paper sheet area in the direction of Find the positional data of the area that will be the addition value, then find the mode of this positional data for each side of the paper sheet, and define each of the straight line parts defined by this mode as the four effective sides. A method for determining the effective four sides of rectangular paper sheets. (3) The method for determining four effective sides of rectangular paper sheets according to claim 1 or 2, wherein the paper sheets are banknotes.