JPH0148587B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field to which the invention pertains] It relates to an image information processing circuit. In particular, the present invention relates to a circuit that compresses contour shape information of an object in a binary image into one-dimensional information, which is suitable as one of the means for pattern recognition. [Description of Prior Art] The contour tracking method shown in FIG. 1 is often used to measure the contour shape of an object, which is important in image measurement. This method traces the contour of the object 12 in the binary image clockwise 13 or counterclockwise, and traces the contour of the object once, and creates chain codes in eight directions as shown in FIG. Using four-directional codes, tracking directions are sequentially identified, and two-dimensional information about the outline of the object is compressed into one-dimensional information. In order to perform this contour tracing at high speed, there is a method that relies on hardware, but the circuit becomes complicated and there are few examples of such conventional circuits. Furthermore, when using a CPU or the like to make direction judgments associated with contour tracking, real-time processing is difficult, making it unsuitable for high-speed processing. [Object of the Invention] An object of the present invention is to provide a circuit that measures the contour shape using a method that replaces the conventional contour tracking method, and eliminates the disadvantages of the contour tracking method associated with the aforementioned high-speed image processing. shall be. [Summary of the Invention] Instead of directly generating a chain code using the contour tracking method, the present invention first generates a containment code by raster scanning, and processes this code to correspond to the contour shape of a binary image. It generates a chain code, and includes an input terminal into which a binary image scanned in a plane according to horizontal and vertical synchronization is input, and a circuit that numbers each pixel represented by the signal of this terminal for each image area. , a circuit that generates a containment code for four adjacent pixels of the screen represented by the signal input to the input terminal, and a set of the image area number and the containment code for that pixel for each pixel. a processor connected to the memory circuit for rearranging the addresses of the memory contents of the memory circuit; and a processor connected to the memory circuit for rearranging the addresses of the memory contents of the memory circuit; It is characterized by including means for rearranging addresses so that they are equivalent to chain codes. [Explanation based on Examples] The present invention will be described based on the drawings. FIG. 3 is a block configuration diagram showing the configuration of the embodiment circuit. First, the configuration of the circuit of this embodiment will be explained based on FIG. This circuit includes an image signal input terminal 30 that inputs binary signals of "1" and "0" obtained by raster scanning a binary image to be measured, and a containment code generation circuit 31.
, a control logic circuit 32 , an area numbering circuit 33 , and a chain code generation circuit 3
4 and a timing generation circuit 35, furthermore, the containment code generation circuit 31 includes a one-line memory 3 that provides a delay of one horizontal scanning period.
In addition, the chain code generation circuit 34 includes a number buffer circuit 341, a number selector circuit 342, a data memory 343, and a rearrangement processor 344.
and a containment code counter 345. Next, the connections of the circuit of this embodiment will be explained based on FIG. The terminal 30 is connected to an image signal source (not shown), and is connected so as to input this image signal to a containment code generation circuit 31. The output of the containment code generation circuit 31 is connected to the input of the control logic circuit 32. The containment code output of the control logic circuit 32 is the area numbering circuit 3.
3, and the control signal output of the control logic circuit 32 is connected to the number selector circuit 34 of the chain code generation circuit 34.
It is also connected to the second input. Furthermore, the containment code output of the control logic circuit 32 is connected to the input of the data memory 343 of the chain code generation circuit 34, and the timing signal output of the control logic circuit 32 is connected to the input of the data memory 343 of the chain code generation circuit 34. Connected to the input of containment code counter 345. Further, the output of the area numbering circuit 33 is connected to the input of the number buffer circuit 341 of the chain code generation circuit 34. The output of number buffer circuit 341 is connected to the input of number selector circuit 342. The area number signal output from number selector circuit 342 is connected to an input of data memory 343, and the output of the containment code counter is connected to be provided as an address to data memory 343. The output of data memory 343 is connected to the input of reorder processor 344. The output of timing generation circuit 35 is connected to the data memory 343 of the chain code circuit and the input of number buffer circuit 341. Next, prior to explaining the operation of the circuit of the present invention, the main points of the drawings from FIG. 3 to FIG. 13 and the tables from Tables 1 to 4 used for this explanation will be explained. FIG. 3 is a block configuration diagram showing the configuration of the circuit of this embodiment as described above. Figure 4 shows a mask composed of four adjacent pixels input to the 2x2 mask circuit in Figure 3.
This shows the names of the four frames of the pattern. One set of frames a and b in the figure is called the upper line of the mask pattern, and one set of frames c and d is called the lower line of the mask pattern. To tell. FIG. 5 shows an outline 52 of an object on a screen 50, and
By a line 53 that cuts the object into two regions,
This shows a state in which the area of the screen 50 is divided into three parts, with area numbers "1" and "2" assigned to each of the two parts of the object area, and area number "0" assigned to the background area. is attached. FIG. 6 is a diagram showing a mask pattern that follows the outline of the object shown in FIG. 5. Among the four pixels of the mask pattern, the shaded pixels are obtained by raster scanning. A blank pixel corresponds to a "1" value signal, which indicates that the pixel belongs to the object region in FIG. 5, and a blank pixel corresponds to a "0" value signal, indicating that the pixel belongs to the background region. indicates that it belongs to Note that the black dots on the object outline in this figure indicate the common points of the four pixels of the mask pattern. FIG. 7 is a diagram showing a mask pattern generated on a line defined by the arrowed line c drawn in FIG. However, the background mask patterns on the left and right sides of the object are omitted. FIG. 8 shows the containment codes on the contour of the object shown in FIG. 5, classified into lower left codes and upper right codes. Here, the lower left chord is a general term for the left-hand chords numbers 1, 8, 9, 11, and 13 of the containment codes Cc shown in FIG. 12, and the containment code number 3. The upper right chord is a general term for the right-side chords numbers 2, 4, 6, 7, and 14, and the containment chord number 12. However, the containment codes numbered 5 and 10 are the same as the containment codes numbered 1 and 4 and number 2, respectively.
and the containment code of 8 will be treated as a combination. Containment on the area 80 indicated by short vertical lines on the outline of the object in the figure.
The code belongs to the lower left code of area number "1" in Table 3, and the containment code on the dashed part 81 along the outline belongs to the upper right code of area number "1". However, the containment codes on the parts 83 and 84 marked with circles on the outline belong to the upper right code of area number "2", and the containment codes on the part 82 marked with an x on the outline belong to the upper right code of area number "2".・The code belongs to the lower left code of area number "2", and is part 85 indicated by the black circle on the outline.
The upper containment code belongs to the lower left code of area number "2'", and the containment code on the part 86 marked with a solid line along the contour line
The code belongs to the upper right code of area number "2'". In addition, in the figure, reference numeral 800 and reference numeral 85
Partial surfaces indicated by 0 indicate areas "1" and "2", respectively, and the parts surrounded by circles marked with numerals 825 and 875 respectively indicate the curved part of the U shape and the curved part of the ∩ shape. 9 to 12 are logical flowcharts showing the process of sequentially converting codes from Table 2 to Table 4, and illustrate the operation of rearrangement processor 344. That is, the process in which the stored contents of the data memory 343 are converted into a chain code that goes around the outline of the image object is shown. Figure 9 shows the outline and order of the processes in Figures 10 and 11. In the process of Figure 10, the conversions shown in Tables 2 to 3 are performed, and
In the process shown in FIG. 1, conversion from Table 3 to Table 4 is performed. FIG. 12 shows the correspondence between the mask pattern, the containment code Cc, and the clockwise chain code Cd, and a direction code is also added to the chain code. This containment code Cc is a code of a combination of four pixels, and for the pixels in frames a to d of the mask pattern shown in FIG. 4, a is "1" and b is "2". , c is weighted with "4" and d is weighted with "8", and numbers from "0" to "15" are given to combinations of four pixels. This containment code Cc indicates a combination of four pixels, can be automatically attached once a mask pattern is determined, and has a correspondence relationship with a chain code as shown in FIG. FIG. 13 shows a combination of a curved point and a mask pattern at the left end, which is called a curved point pair. There are three types of curved points: upwardly convex, downwardly convex, upwardly concave (hereinafter referred to as U shape), and downwardly concave (hereinafter referred to as ∩shape). be.
The names of the bend points are not affected by the number of mask patterns corresponding to containment code numbers 3 and 12 that are interposed between the bend point pairs. Table 1 shows the judgment criteria of the number selector circuit of the chain code generation circuit 34, and selects the frame temporarily stored in the number buffer circuit 341 corresponding to the containment code from the control logic circuit. The area number within the selected frame is given to the data memory 343. Table 2 shows area numbers and containment codes stored in data memory 343 based on the mask pattern generated along the contour of the object in FIG. However, the x mark shown in the area number row indicates the case where the area number is not selected by the number selector circuit 342. Table 3 is a table created by combining the area numbers shown in FIG. 8, the lower left code, and the upper right code, and the containment codes belonging to each combination are added to the logical flowchart shown in FIG. 10. This shows the state processed according to the method shown in . Table 4 shows the state in which the data classified as shown in Table 3 is converted into a chain code that goes around the outline of the image area through the processing shown in the logical flowchart of FIG. A containment code is also included to clarify the relationship between this table and Table 3, and also to indicate the compressed state of the data.

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[Usage form]

(1) Reproduction of binary image and calculation of contour point coordinates XY coordinate data memory 32 shown in Fig. 14
By adding this to the circuit shown in FIG. 3, image reproduction and coordinate calculation can be performed. That is, this XY coordinate data memory stores the containment number 8 when a pair of convex curved points above the control logic circuit appears.
This is a circuit that stores the coordinates of points on the contour indicating the code. The point indicated by these coordinates indicates the starting point for creating a chain code that goes around the outline of the object, and the original binary image can be reproduced using the coordinates of this point and the chain code. It is also possible to calculate the coordinates of each contour point. (2) Expression of contour shape using polar coordinate system This will be explained based on FIGS. 15 and 16. FIG. 15 shows the outline 130 of the object, the fixed point 131 on the object, for example, the coordinates of the center of gravity (Xc, Yc), the coordinates of the starting point 132 (X ₀ , Y ₀ ), and the fixed point 1
31 as the origin, a line connecting the fixed point 131 and the starting point 132 as the reference line of the polar coordinates, and shows a state in which a vector 135 indicating the polar coordinates moves on the contour of the object. The horizontal axis in FIG. 16 indicates the order number of the contour points or the deviation angle 134 of the vector 135 which is the reference line, and the vertical axis indicates the length of the vector 135, that is, the distance from the center of gravity 135 to a point on the contour 130. The figure is drawn with the starting point 132 as the origin. Contour shape information can be expressed using this method, but if a chain code is used at this time, the distance of a point on the contour from a fixed point
Calculation of Ri can be easily performed. In other words, let the coordinates of a point on any contour be (Xi,
Yi), and ^the distance between ^the starting point and the fixed point is R ₀ , then R ₀ ² = ( _X 0 ⁻ , each corresponds to the chain code as shown below. That is, a change of "+1" in the X coordinate corresponds to the appearance of chain codes numbered 1, 2, and 8, and therefore Ri ² = (R _i-1 ) ² + 2 (Xi - Xc) + 1 "-1" change is number 5, 4, 6
Therefore, Ri ² = (R _i-1 ) ² + 2 (-Xi-Xc) + 1 A change of "+1" in the Y coordinate corresponds to the occurrence of the chain code of numbers 3, 4, 12
Therefore, Ri ² = (R _i-1 ) ² + 2 (Yi - Yc) + 1 Also, the change of "-1" in the Y coordinate corresponds to the appearance of the chain code of number 7,
The distance between a point on the contour and a fixed point can be determined by Ri ² =(R _i-1 ) ² +2(-Yi-Yc)+1. (3) Calculation of area and circumference To calculate the area product of an object, based on the coordinates of the contour point determined by the method (1) above, determine whether the contour point belongs to the right-hand code or the left-hand code. , when it belongs to the right-hand code, add it, and when it belongs to the left-hand code, perform subtraction, and then go around the contour. In this case, the coordinates may be coordinates with the starting point as the origin. In addition, the circumference is calculated using a series of mask patterns obtained by one line of raster scanning, with containment codes numbered 1, 2,
4, 7, 8, 11, 13, and 14 by measuring it as “√2/2” and when the containment code is number 3, 6, 9, and 12, it should be measured as “1”. Can be done. [Effects of the Invention] The present invention can generate a chain code corresponding to the contour shape in a binary image using raster scanning, so real-time processing can be performed using simpler hardware than contour shape measurement using the conventional contour tracking method. It can be carried out. Also, since the binary image is converted into one-dimensional data, data compression is performed, and therefore it is convenient for signal transmission and storage. Furthermore, in addition to the area and circumference of the object, information on the irregularities of the outer periphery can also be obtained, which is convenient for identifying the outer shape during pattern recognition.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram explaining the contour tracking method. FIG. 2 is a diagram explaining a chain code. FIG. 3 is a block configuration diagram showing the configuration of a circuit according to an embodiment of the present invention. FIG. 4 is an explanatory diagram of frame names of a 2×2 mask pattern. FIG. 5 is an explanatory diagram showing area numbers of images. 6th
The figure shows a state in which contour containment codes are generated. FIG. 7 is a diagram showing how a containment code is generated by a specific raster scan. FIG. 8 is an explanatory diagram showing area numbers of contours. 9-11 are logic flow diagrams illustrating the operation of the reordering processor. FIG. 12 is a comparison diagram of signals. FIG. 13 is an explanatory diagram of curved point pairs. FIG. 14 is a diagram showing the connection of the XY coordinate data memory and input/output. Figure 15 and 1
Figure 6 is an explanatory diagram of contour shape expression using the polar coordinate system. 11... Scanning line, 12, 130... Object outline, 30... Image signal input terminal, 31... Containment code generation circuit, 32... Control logic circuit, 33... Area numbering circuit,
34... Chain code generation circuit, 35... Timing generation circuit, 50... Screen, 52... Outline of object, 53... Target area cutting line, 90...
Coordinate data memory, 91...X coordinate signal input terminal, 92...Y coordinate signal input terminal, 131...fixed point, 132...start point, 133...arbitrary point on area number, 134...deviation angle, 135... ...Polar coordinate vector, 311...One line memory, 312...
2×2 mask circuit, 341...Number buffer circuit, 342...Number selector circuit, 343...Data memory, 344...Reordering processor,
345...Containment code counter.

Claims (1)

[Claims] 1. An input terminal into which a binary image plane-scanned according to horizontal synchronization and vertical synchronization is input, and a circuit that numbers each pixel represented by the signal of this terminal for each pixel area; A circuit that generates a containment code indicating a combination of four adjacent pixels on the screen represented by a signal input to the input terminal; A memory circuit that stores the content codes as a set, and a processor that is connected to the memory circuit and rearranges the addresses of the memory contents of the memory circuit. 1. A contour shape information extraction circuit comprising means for rearranging addresses so that the chain code is equivalent to a chain code that goes around the contour of the image area.