JP3001950B2 - Rectangle extraction device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image processing such as character recognition and, more particularly, to a rectangle extraction device that performs rectangle extraction at high speed.

(Prior art)

The conventional rectangle extraction processing will be described with reference to the drawings. First, a run (black connection) is extracted from image data taken in from an image scanner or the like. FIG. 3 shows runs extracted by raster-scanning each line of the image, and FIG. 4 shows run 1 to run 3 in which the run is enlarged.
Here, the run data includes the x and y coordinates of the start point and end point (the start point of run i is xsi, ysi, and the end point is xei, yesi) and a pointer Pki to the rectangular data to which the run belongs. A plurality of run data on the previous line is written to the run data memory area 52 (FIG. 5), and a plurality of run data on the current line is written to the run data memory area 51.
Then, rectangles are generated one after another by examining the connection relationship (four connections or eight connections) between the run of the current line and the run of the previous line.

That is, assuming that Run 3 is a run on the current line and Runs 1 and 2 are runs on the immediately preceding line, the run data 1 of Run 1, that is, the x and y coordinates (xs1, ys1, x
e1, ye1) are written to the area 52. Assuming that there is no run before run 1, since run 1 forms a rectangle, its rectangular data K1 (the coordinates of its start point and end point, ie, xs1,
ys1, xe1, ye1) are written to the rectangular data area 53. Then, the pointer of the run data 1 points to the rectangular data K1
Pk1 is written (FIG. 5).

Similarly, if it is determined that the run 2 is not connected to the run 1 at this time, the run data 2 (xs2, ys2, xe
2, ye2) is written to the area 52, and the rectangular data K2 (xs
2, ys2, xe2, ye2) are written in the rectangular data area 53, and Pk2 pointing to the rectangular data K2 is written in the pointer of the run data 2 (FIG. 5).

Next, the processing moves to the current line, and when run 3 is extracted, the run data 3 (xs3, ys3, xe3, ye3) is stored in area 5
1 is written, and the connection relationship with run 1 on the previous line is checked first. Since run 3 does not yet belong to any rectangle, if run 3 is connected to run 1,
Update the rectangular data K1 to which. That is, the sixth
As shown in the figure, the end point coordinates of the rectangular data K1 are rewritten from xe1, ye1 to xe3, ye3 (end point coordinates of run 3), and Pk1 pointing to the rectangular data K1 is written in the pointer of run data 3 (No. 6).

Further, the connection relationship between the run 3 and the run 2 on the previous line is checked, and if the run 3 is connected to the run 2,
Since the run 3 already belongs to the rectangular data K1, the rectangular data K2 is integrated with the rectangular data K1. That is, the end point coordinates of the rectangular data K1 are rewritten from xe3, ye3 to xe2, ye2 (end point coordinates of run 2), and the pointer (Pk
2) is rewritten to Pk1 indicating the rectangular data K1 (7th
Figure).

In order for the above process to be performed correctly, all the run data must hold pointers to the rectangular data to which the run data belongs.

[Problems to be solved by the invention]

That is, when rectangles are integrated as described above,
The pointer of the run data belonging to the unified rectangle data is no longer valid, so correct this.
The pointer must be updated to point to the unified rectangle. Therefore, it is necessary to check all the run data on the current line. For example, if the run m in FIG. 7 points to the rectangular data K2 which is no longer valid,
The pointer of the run m must be corrected, which causes a problem that the processing speed is greatly reduced.

The integrated rectangular data (rectangular data K in FIG. 7)
2) becomes a garbage, so that there is a problem that the use efficiency of the rectangular data area 53 is deteriorated. Although it is possible to reuse this area, the processing is expensive for the following reasons. That is, it is generally required that rectangular data be read in the order in which it appears when scanning pixel data. Therefore, if the integrated rectangular data area (eg, K2) is used to register other rectangular data, when reading rectangular data in order from the lowest address, the reading order of rectangular data in the area must be managed. The problem that it does not occur.

Further, as described above, since a large amount of dust data is included in the rectangular data area, there is a problem that such dust must be skipped when reading rectangular data. In general, it is also possible to provide a flag in the rectangular data as to whether the data is valid or not, to check all data at the time of reading, and to extract only valid data. In this case, there is a problem that the amount of processing data increases and a great deal of time is spent for processing.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rectangle extracting device capable of performing processing of rectangular data at high speed.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, there is provided a rectangle extracting apparatus for extracting a rectangle from image data.
A first storage unit which stores rectangular data including an identification number of the rectangle and a flag indicating whether the address is used or not.
Storage means for storing the start point and end point data of the run of the current line and the run of the previous line, the identification number of the rectangle to which the run belongs, and the first run on the previous line. The first rectangle to which the second run belongs, the second rectangle to which the second run belongs, and the respective flags are displayed for use and stored in the first storage means, and the first and second rectangles on the previous line are displayed.
And the third run on the current line are stored in the second storage means, and the connection relationship between the run of the current line and the run of the previous line is checked by referring to the second storage means. When the first, second and third runs are connected, the first,
The second rectangle is integrated, the flag of the integrated rectangle is displayed as unused, and the identification number of the run belonging to the integrated rectangle is changed to the identification number of the integrated rectangle. And control means for performing the control.

In the invention according to claim 2, when the third run is not connected to the first and second runs, the third run is set as a new rectangle and the flag of the first storage unit is not used. Is registered at the address that displays.

The invention according to claim 3 is characterized in that reading of the rectangular data from the first storage means is performed by referring to a flag indicating the use.

(Operation)

Run data is created from the pixel data read by the image data interface unit and written to the run data associative memory. The first run data is registered as rectangular data. In this registered area (address), an unused area is found by the search function of the associative memory at the address of the associative memory where the garbage flag is set.

Subsequently, the connection relationship of each run data is checked from the run data of the previous line and the run data of the current line, and if connected, the integration process is performed. As a result of the merging, the garbage flag of the merged rectangular data is set, so that this area can be reused. All the run data on the current line belonging to the integrated rectangular data are searched, and the value of the id of the belonging rectangular pointer field of the searched run data is changed to the value of the rectangular data identification number id on the integrated side. In the rectangle reading process, only valid rectangle data is retrieved by searching for a rectangle data whose garbage flag field is reset by a match search.

〔Example〕

Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a block diagram of a rectangle extracting apparatus according to one embodiment of the present invention. Reference numeral 1 denotes an associative memory for storing rectangular data. Each word includes an x-coordinate and a y-coordinate of a starting point and an ending point of the rectangle, an identification number id of the rectangle, and a garbage flag indicating whether or not this address is used. 6
Consists of fields. Reference numeral 2 denotes a run data associative memory for storing run data in the current line and the previous line. The run data includes x and y coordinates of a start point and an end point, a pointer to a belonging rectangle, that is, an identification number of the belonging rectangle. Has become. Reference numeral 3 denotes an image data interface unit that captures pixel data from a scanner or image data memory or the like. Reference numeral 4 denotes a control unit that controls the above units, and manages the identification number id of the rectangle.

Note that the associative memory used in this embodiment means a memory whose address can be obtained as a result of performing a search on the contents under conditions such as magnitude comparison or agreement. These addresses can be read out to the output register of the associative memory in ascending order. Also, the configuration is such that comparison can be made for each field by using a mask register.

The operation of the rectangle extracting apparatus of the present invention configured as described above will be described in detail by taking the run of FIG. 4 as an example. Prior to the processing, all the garbage flag fields of the associative memory 1 are set, and the control unit is controlled. The rectangular data identification number id of 4 is reset to 0.

Next, the control unit 4 creates run data from the pixel data read by the image data interface unit 3 and writes it to the run data associative memory 2. Since there is no previous line for the first line 1, the first run data 1
(Run 1) is registered as it is as rectangular data (K1).

Registration process; This registration process is performed as follows. Control unit 4
Searches the address of the associative memory 1 where the garbage flag is set by the associative memory search function. Since the address found by this search is an unused area, rectangular data (K) as shown in FIG.
Write 1). In FIG. 2A, the starting point field 21 of the rectangle is the x coordinate value (xi1) and y coordinate value (yi1) of the starting point of the run data (run 1), and the ending point field 22 of the rectangle is the x coordinate value of the ending point. (Xi2) and the y coordinate value (yi2), the identification number 1 is written in the rectangular data identification number id23, and 0 (reset) is written in the garbage flag field 24.

Also, as shown in FIG. 2 (b), the start point and end point coordinate values of the run 1 are written in the run data associative memory 2, and the identification number 1 is written in the belonging rectangle pointer field of the current line. Thereafter, the control unit 4 sets the rectangular data identification number id to 1
Only increase.

Next, run 2 of the current line is extracted, and this run 2
Is not connected to the run 1, the rectangular data (K2) and the run data (run 2) are stored in the memory 1 as shown in FIGS. ,
2 is written. Also, id =
2 is written, and 0 is set in the garbage flag field 24.
(Reset) is written. Thereafter, the control unit 4 increases the rectangular data identification number id by 1 (id = 3).

Subsequently, the control unit 4 clears the run data area of the current line by moving the run data of the current line 1 to the run data area of the previous line. Since it takes time to actually perform the data movement processing, pointers to the two areas are prepared, and the processing is performed so that these are replaced.

Then, the pixel data of the next line 2 is read, and run data (run 3) is created in the run data area of the current line (FIG. 2 (e)).

The control unit 4 refers to the memory of FIG. 2 (e), and based on the run data of the previous line 1 (runs 1 and 2) and the run data of the current line 2 (run 3), the connection relationship of each run data (run 3). 4
(Concatenation or 8 concatenation), and if not connected, rectangular data is registered in the same manner as described above, and if connected, integrated processing is performed. If Run 3 is not connected to Runs 1 and 2, Run 3 is registered as rectangular data (K3) with identification number 3 attached.

In the example of FIG. 4, since the runs 1, 2, and 3 are connected, first, the rectangular data (K1) and the run 3 are integrated, as described in the related art. In other words, the start point and the end point data of the rectangular data (K1) are rewritten by the integration processing, and since the run 3 belongs to the rectangle K1, the pointer is set to 1
To Next, the rectangle K1 and the rectangle K2 are integrated, and the start point and end point data of the rectangle K1 are rewritten.

As a result of the integration, the garbage flag of the integrated rectangular data (K2) is set (set to 1), and this area can be reused.

Search for all run data on the current line that belonged to the integrated rectangular data (K2). This search is performed by searching for data in which the integrated rectangle data identification number id value (id = 2) is written in the belonging rectangle pointer field of the run data. Then, the id value (id
= 2) is changed to the value (id = 1) of the rectangular data identification number id on the unified side.

Rectangle reading processing: The above processing is performed on all pixel data, and when the processing is completed, rectangle reading processing is performed.

That is, only valid rectangular data is searched by searching for a rectangular data whose garbage flag field is reset by a match search. Among the searched rectangular data, the one in which the y-coordinate field of the starting point of the rectangular data has the minimum value is searched. Further, the search result having the minimum value in the x coordinate field of the starting point of the rectangular data is searched.

Based on this search result, the first rectangular data is read from the output register of the associative memory 1. The garbage flag field of the read rectangular data is set so that the data is not read again.

The above process is repeated until all the rectangular data is read.

〔The invention's effect〕

As described above, according to the present invention, since the updating process of the belonging rectangle pointer is performed at high speed, the processing speed of rectangle extraction is significantly improved as compared with the conventional one. Further, since the area of the integrated rectangular data can be reused, the use efficiency of the memory is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a rectangle extracting apparatus according to an embodiment of the present invention. FIGS. 2 (a) and 2 (c) are diagrams showing an example of rectangle data registered in a rectangle data associative memory. 2 (b), (d), and (e) show examples of run data written in the run data associative memory, and FIG. 3 is extracted by raster-scanning each line of an image. FIG. 4 is a diagram showing a run, FIG. 4 is a diagram showing an enlarged run, and FIGS. 5, 6, and 7 are diagrams for explaining a conventional rectangle extraction process. 1 ... rectangular data associative memory, 2 ... run data associative memory, 3 ... image data interface unit, 4 ... control unit.

Claims (3)

(57) [Claims] 1. A rectangle extracting apparatus for extracting a rectangle from image data, comprising, for each address, start and end point data of the rectangle, an identification number of the rectangle, and a flag indicating whether or not the address is used. First storage means for storing rectangular data consisting of: a start point and an end point data for the current line run and the previous line run; and an identification number of the rectangle to which the run belongs; The first rectangle to which the first run belongs on the previous line, the second rectangle to which the second run belongs, and the respective flags are displayed and stored in the first storage means. The first run, the second run, and the third run on the current line are stored in the second storage means, and the connection between the current line and the run of the previous line is referred to by referring to the second storage means. Investigate the relationship, the first, second When the third run is connected,
The first and second rectangles are integrated, the flag of the integrated rectangle is displayed as unused, and the identification number of the run belonging to the integrated rectangle is changed to the value of the integrated rectangle. And a control unit for changing the identification number to an identification number. 2. When the third run is not connected to the first and second runs, the third run is defined as a new rectangle.
2. The rectangle extracting apparatus according to claim 1, wherein the flag is registered in an address where the flag of the first storage means indicates unused. 3. The rectangle extracting apparatus according to claim 1, wherein the reading of the rectangular data from the first storage means is performed by referring to a flag indicating the use.