JPS5845746B2 - Contour tracking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contour tracking method for recognizing two-dimensional patterns such as characters and figures.

Conventionally, this type of method used a flying spot scanner to track the outline of characters written on paper, but if a device was configured using this method, it would be expensive and large. Since this method uses a shaped flying spot scanner, the device has disadvantages such as high cost and large size.

Furthermore, a method of tracing the contours of two figures has been proposed in the past, but the conventional method has the drawback that the inner contour of a loop figure with a line width of 1 pixel cannot be traced.

The conventional method is shown in Fig. 1, Fig. 2, Fig. 7, Fig. 8, and Fig. 9.
This will be explained using figures.

FIG. 1 is an example of a binarized loop figure with a line width of 1 pixel, where loop 1 indicates the figure part and logic 0 indicates the background part.

FIG. 2 shows the contour to be traced of pattern 1 in FIG. 1, in which 2 is the outer contour of pattern 1, and 3 is the inner contour.

The logic l pixels connected to this contour in four directions in the vertical and horizontal directions are defined as contour points.

Since pattern 1 in FIG. 1 is a loop figure with a line width of 1 pixel, some pixels of logic 1 serve both as outer contour points and inner contour points.

FIG. 7 shows the state of the storage device that has stored the figure shown in FIG. 1, and each storage means stores a value of 1 or O corresponding to each pixel in FIG. 1.

FIG. 8 shows the state of the storage device after tracking the outer contour, and the values in the storage device corresponding to the contour points for which tracking has been completed range from 1 to 2.
It has been rewritten as .

FIG. 9 shows the order in which the next contour point is searched from the contour point being tracked.

X is the position of the contour point being tracked. It is assumed that the contour point tracked immediately before is located at number 8, and numbers 1 to 7 are at number 8.
It is attached counterclockwise with reference to .

The values in the storage means corresponding to each pixel are checked in the order of numbers 1 to 8.

Contour tracking is performed as follows.

In the state of the storage device shown in FIG. 7, values in the storage means corresponding to each pixel are sequentially checked from the storage means corresponding to the pixel at the upper left corner of FIG. 1 toward the right.

Starting from the storage means whose value changes from O to 1 (second column, second row in FIG. 7), storage means whose value is 1 or 2 are detected in the order shown in FIG.

Next, the tracking point is transferred to the storage means, and the value of the storage means corresponding to the tracked pixel is rewritten to 2.

By repeating this process and returning to the starting point, the outer contour tracing is completed as shown in FIG.

Next, in the state of the storage device shown in FIG. 8 after tracking the outer contour, even if you try to detect the starting point for tracing the inner contour in the same way as before, the storage device whose value changes from O to 1 will not work. The starting point cannot be detected because it does not exist.

As described above, the conventional method has the disadvantage that it is not possible to trace the inner contour of a loop figure having a line width of one pixel as shown in FIG.

In order to eliminate these drawbacks, this invention has a device that detects and stores the outline of a binarized pattern. Even if a simple input sensor such as a line scanner is used, a loop with a line width of 1 pixel can be created. This system is designed to reliably trace even the inner contour of a figure, and the drawings will be explained in detail below.

Figure 3 shows the logical values of 2x2 pixels on a two-dimensional pattern,
It is a diagram showing the logical values of four storage means at the memory address corresponding to the above-mentioned 2×2 pixels, and in the figure, 4 is a set of 2×2 pixels, and 5 is a set of 2×2 pixels. A set of four storage means at the storage address corresponding to set 4, where 51 to 54 are 2×2
are each pixel of the set 4 of pixels, and 55 to 58 are each storage means of the set 5 of four storage means.

A general random access memory is used as the storage means, but the expression shown in FIG. 3 is used to clearly explain the correspondence with the direction in which the contour exists.

The same expression is used in FIGS. 5 and 6.

Figure 4 shows a 2 x 2 pixel set 4 including a virtual pixel with logical value O outside the outermost part of the two-dimensional pattern, and four memories at memory addresses corresponding to the 2 x 2 pixel set 4. Means set 5 is shown, 59 to 62 are each pixel of 2×2 pixel set 4, and 6
3 to 66 are storage means of the set 5 of four storage means.

Next, the method of contour detection will be described.

In FIG. 3, there is a set 4 of 2×2 pixels and a set 5 of four storage means, and there is a storage means 55 corresponding to pixels 51 and 52, and similarly, pixels 52 and 53, There are storage means 56, 57, and 58 corresponding to the pairs of pixel 53 and pixel 54, and pixel 54 and pixel 51.

Then, when a pair of pixels, for example, pixel 53 and pixel 54, take different logical values, the logic 1 is stored in the storage means 57 corresponding to the pair of pixels, and the pair of pixels, for example, pixel 5
When 1 and pixel 52 have the same logical value, logic 0 is stored in the storage means 55 corresponding to the pair of pixels.

When there is a logic 1 pixel 60 on the outermost side, as shown in FIG. A value can be determined.

By performing the above processing on all the 2×2 pixel sets 4 on the pattern 1, the outlines 2 and 3 of the pattern 1 can be stored in the storage means.

Figures 5 and 6 correspond to mxn pattern 1 (m
+1 ) This shows the state after tracking the outer contour of the figure.

In the figure, 6 is a storage device having four storage means corresponding to each of the above (m+1) x (n+1) storage addresses, and 10 to 49 are storage means having logic 1.

Although the storage means of the storage device 6 are not necessarily arranged in a two-dimensional square as shown in the figure, the representation shown in the figure is used to make it easier to understand the correspondence with each pixel of pattern 1.

Note that storage addresses where all the logical values of the four storage means are O are shown as blank spaces.

Next, we will discuss the contour tracking method.

In FIG. 5, the memory means corresponding to the position are sequentially checked from the upper left corner to the right, and first, among the four corresponding memory means, the state of the memory means corresponding to the lower contour is 1.
Detects a 2×2 pixel set with It will be equivalent.

) in the direction of looking at the logic O pixels to the right and the logic 1 pixels to the left in the direction of the contour line, 1 is obtained.
It can be traced in numerical order such as 0, 11, 12, etc., and logical 0s are written where it passes.

By tracing to the storage means 37, the tracing of the outer contour 2 of the pattern 1 is completed.

The tracking method will be explained in more detail.

Tracking is performed according to two rules:

The first rule is a processing method within the same memory address, and 4
The contents of two storage means are examined counterclockwise from the starting point.

For example, in FIG. 3, when the tracked position is in the storage means 56, the storage contents are checked in the counterclockwise direction starting from this point, that is, in the order of the storage means 55, 58, and 57, and the first storage means 57 whose logic is 1 is checked. Move the tracking position to .

A logic O is written in the storage means that has been tracked.

When all of the storage means 55, 58°5γ are at logic O, the tracking ends.

The second rule is how to move memory addresses.

When the tracking position is once moved within the same storage address, the tracking position is moved to the storage means opposite to the storage address adjacent to the storage means, and that storage address is stored.

Note that the second rule is applied to the starting point storage means.

If the above rules are followed, for example, if the tracking position is in the storage means 23 in FIG. .

By tracking the storage means in this way, consecutive storage addresses can be stored.

In this way, when the tracing of the outer contour 2 of the pattern 1 is completed, the logical values of the storage means are as shown in FIG.

Next, in the same manner as for the outer contour, starting from the storage means 38 and tracing from the storage means 38 to the storage means 49 in the same way, the tracing of the inner contour 3 of the pattern 1 is completed.

Then, contour tracking ends with all storage means set to logic 0.

With this method, the contour can be completely traced with a simple device without using an expensive and large flying spot scanner.
Even the inner contour of a pixel loop figure can be tracked reliably.

Note that the above has one segment, and the surrounding area is logically O.
Although a two-dimensional pattern surrounded by pixels has been described, the present invention is not limited to this, and can be used for two-dimensional patterns having two or more segments.
Even if there are logic 1 pixels around the , it can be used by assuming logic 0 pixels outside of it.

Moreover, although the starting point of tracking and the direction of tracking are only one example, they are not limited to this.

As described above, according to the present invention, by using a storage means that stores the outline of a two-dimensional pattern in advance, outline tracking can be performed completely with a simple device, which has the advantage that an inexpensive recognition device can be created. There is.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of a binarized two-dimensional pattern such as characters and figures, Figure 2 is a diagram showing the outline of the two-dimensional pattern in Figure 1, and Figure 3 is a diagram showing the outline of the two-dimensional pattern described above. FIG. 4 is a diagram showing the logical values of 2×2 pixels and the logical values of four storage means at the memory address corresponding to the 2×2 pixels. 2 containing pixels with logical value O
A diagram showing the logical values of ×2 pixels and the logical values of the four storage means at the memory address corresponding to the above 2 × 2 pixels. Figure 5 shows the logical values written to represent the outline shown in Figure 2. 6 is a diagram showing a state in which the outer contour has been tracked in FIG. 5, and FIGS. 7 to 9 are
FIG. 2 is a diagram for explaining a conventional method of directly tracing a contour from a binary pattern. In the figure, 1 is the pattern f sleep 2 is the outer ring 1 doctor 3 is the inner ring doctor 4 is a 2 x 2 pixel set on pattern 1, 5 is 2 x 2
6 is a storage device having four storage means at each storage address; 10 to 49 are storage means having logic 1; 51 is a storage device having four storage means at each storage address; ~54 and 59~62 are pixels in 2x2 pixel set 4, 55~
58 and 63-66 are storage means in group 5 of four storage means. Note that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Scope of Claims] 1. In a contour tracing method for a binarized two-dimensional pattern such as a character or figure, (m+1) (
There are n+1 ) memory addresses, and memory address (i, j)
are four adjacent pixels, (i-1°J'), (l
LJ)t(1tJ IL(1+J) corresponds to the set (i21,2... sum+1; j=1,2...n
+1; Pixel (0, j) outside the two-dimensional pattern. (i, O), (m+1.j), (i, n+1) are hypothetical logical O (or logical 1)), and each of the above storage addresses has four binary storage means, 2 of the above 4
The value storage means is a set of two adjacent pixels (i-1
,j-1)(i-1,j),(i-1,j)(i,j
), (i, J) (i, J-1), (i, J-1) (i-
'sJ D, respectively, and when the pair of the two pixels take different logical values, store a logic 1 (or logic O) in the corresponding storage means,
When the above two pixel pairs have the same logical value,
The outline of the two-dimensional pattern is memorized by storing a logic O (or logic 1) in the corresponding storage means, and the outline stored in the storage means, that is, the logic 1 (or logic O) is continuously displayed. A contour tracking method characterized in that the above-mentioned storage means are tracked in consecutive order. 2 While tracing the contours, that is, the memory means that are continuously logical 1 (or logical O) in the order of successive traces, store the logical 0 (or logical 1) in the memory means that have been traced, and store the logical 1 (or logical 1) 2. The contour tracking method according to claim 1, wherein the tracking is completed when the storage means that is in the state of (or logical O) is exhausted.