JPH07262385A - Outline data generator - Google Patents

Abstract

PURPOSE:To provide the method and device for generating outline data so as to efficiently generate a high-quality contour line from the character data of a dot form expressing dot width for more than one. CONSTITUTION:A contour extracting part 140 prepares contour line data by chasing a contour based on the state of adjacent four picture elements surrounding the lattice point of dot data stored in a storage part 12, a smoothing processing part 141 executes smoothing by linking the respective midpoints of plural segments consisting of these contour line data, and a curving processing part replaces series of segments monotonously increasing or decreasing the X and Y coordinate values and the inclination of segments in this smoothed contour line with a Bezier curve provided with two control points.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outline data generator for generating contour line data from dot format data.

[0002]

2. Description of the Related Art Conventionally, fonts used in workstations and document processing apparatuses include not only dot-type fonts used in a dot pattern method, but also outline fonts used in an outline character method.

This outline font is obtained by extracting the outline of the font expressed in dot format.
Often forms letters.

For example, in Japanese Patent Laid-Open No. 63-231392, dots of character data in a dot format are scanned to check flags in the horizontal direction, vertical direction, right diagonal direction and left diagonal direction. There is disclosed a character data format conversion method for converting character data from the dot format to the vector format by checking the connection of black dots while performing.

Further, in Japanese Patent Laid-Open No. 63-188277, after removing noise dots from a target dot image for vector font generation, transition point dots in the X-axis direction and transition point dots in the Y-axis direction of the image are removed. Is disclosed, and the extracted transition point dots in the X-axis direction and the Y-axis direction are combined to obtain contour dot data for vector font generation.

[0006]

However, according to the former prior art, a portion having a line width of 1 dot in a font expressed in a dot format can be extracted as a line segment but as a contour line. Cannot be extracted.

Therefore, when the outline font in which the contour line is extracted is enlarged, the portion in which the contour line is extracted is enlarged, but the portion in which the contour line cannot be extracted cannot be enlarged in the portion extracted as the line segment. , The font shape becomes unbalanced.

In particular, when a contour line is extracted from a low-dot character having a small number of dots forming a font, a large number of line segments represented by a 1-dot width appear, and the above problem becomes apparent.

Further, in the latter technique, the outline of the font is scanned in the X-axis and Y-axis directions and the line segments forming the outline are extracted by linear approximation. The straight line portion and the connected portion of the line become conspicuous, and the poor character quality becomes remarkable.

For this reason, in Japanese Patent Laid-Open No. 3-78888, when the polygonal line is curved, first, the midpoints of the two end points are obtained on the curve using a curving equation, and the midpoints of the midpoint and the end points are calculated. There is disclosed a graphic data processing device that determines the number of divisions according to a straight line distance, divides a curve between end points by the number of divisions, and calculates the coordinates of the division points.

However, in this conventional technique, since the contour line is formed by the line segment passing through the calculated series of division points, it cannot be replaced with a smooth curve.

Therefore, the present invention solves the above problems and provides an outline data generating method and apparatus capable of efficiently generating a high-quality contour line from character data in a dot format in which a dot width is represented by 1 or more. The purpose is to provide.

[0013]

In order to achieve the above object, the present invention provides an outline generator for generating contour line data consisting of a plurality of segments from image information in a dot format formed by arranging a plurality of pixels. , The contour line continuation direction at each grid point located at the contact point of four adjacent pixels is determined in accordance with the value of the four pixels, and the contour line is defined based on the contour line continuation direction at each grid point. It is characterized by further comprising a contour extracting means for tracing a line and extracting contour line data.

Further, the present invention is a continuous segment among a plurality of segments forming a contour line, in which the X coordinate value at the end point of each segment monotonically increases or decreases, and the Y coordinate value at the end point. Monotonically increases or monotonically decreases, and further detects a plurality of segments in which the inclination of each segment monotonically increases or monotonically decreases, and the coordinate values of the start and end points of the continuous segments detected by the detector and each segment. And a curve forming means for replacing the continuous segment with a Bezier curve having two control points on the basis of the slope of.

Further, according to the present invention, in an outline generating apparatus for generating contour line data consisting of a plurality of segments from dot-form image information constituted by arranging a plurality of pixels, contact points of four pixels adjacent to each other are provided. The continuous direction of the contour lines at the respective grid points located is obtained corresponding to the values of the four pixels, and the contour lines are traced based on the continuous direction of the contour lines of the respective grid points to extract the contour line data. A contour extracting means, a smoothing means for replacing the continuous segments extracted by the contour extracting means with a new segment connecting the midpoints of the segments; and a plurality of segments forming the contour line. The X coordinate value at the end point of each segment monotonically increases or decreases and the Y coordinate value at the end point monotonically increases or decreases. Then, further, the detection means for detecting a plurality of segments in which the inclination of each segment monotonically increases or decreases monotonically, based on the coordinate values of the start and end points of the continuous segments detected by the detection means and the inclination of each segment, And a curve forming means for replacing the continuous segment with a Bezier curve having two control points.

[0016]

According to the present invention, when the contour line data is generated from the image information formed by arranging the dot data, that is, the pixels to which the values are given, in a grid pattern, the contour extracting means sets the four adjacent pixels. The continuous direction of the contour line at each grid point located at the contact point is obtained corresponding to the values of the four adjacent pixels, and the contour line data is obtained by tracing the grid points based on the directionality of each grid point. Extract.

Thus, the outline data can be extracted even from the line segment having the width of 1 dot.

Further, according to the present invention, among the plurality of segments forming the contour line, the X coordinate value at the end point of each segment is a monotonous increase or monotonous decrease and the Y coordinate at the end point is continuous. The detecting means detects a plurality of segments whose coordinate values monotonously increase or monotonically decrease, and the inclination of each segment monotonically increases or monotonically decreases, as the segments to be curved, and the curvilinearizing means detects the segments. Based on the coordinate values of the start and end points of the continuous segment and the slope of each segment, the continuous segment is replaced with a Bezier curve having two control points.

Thus, it is possible to easily curve a predetermined continuous segment.

Further, according to the present invention, when the contour line data consisting of a plurality of segments is generated from the image information in the dot format constituted by arranging a plurality of pixels, the contour extracting means,
The connecting direction of the contour lines at each grid point located at the contact points of the four pixels adjacent to each other is obtained corresponding to the value of the four pixels, and the contour line is based on the connecting direction of the contour lines at each grid point. To extract contour line data, and the smoothing means sets the midpoint of each segment to a continuous segment formed stepwise among a plurality of segments forming the extracted contour line. Replace with a new concatenated segment. The detecting means is a continuous segment among the plurality of segments forming the contour line, and the X coordinate value at the end point of each segment monotonically increases or decreases, and the Y coordinate value at the end point monotonically increases. Alternatively, a plurality of segments that monotonically decrease and the gradient of each segment monotonically increases or monotonically decreases is detected, and the curving means detects the coordinate values of the start and end points of the detected continuous segments and the gradient of each segment. To replace the continuous segment with a Bezier curve with two control points.

Thus, the outline data including the Bezier curve can be easily generated from the dot format image information.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an outline data generating device according to the present invention.

As shown in FIG. 1, this outline data generating apparatus is an apparatus for generating outline data from a dot format font, and has an input unit 10 and an output unit 1.
1, a storage unit 12, a memory 13, and an outline data generation unit 14.

The input unit 10 is an input unit for giving an instruction to create outline data, and is composed of a pointing device such as a mouse or a keyboard.

The output unit 11 is an output destination to which the outline data generated by the outline data generation unit 14 is output, and corresponds to, for example, an image memory when displaying the outline data.

The storage unit 12 is a storage unit for storing various font data (hereinafter referred to as "dot data") expressed in a dot format which is a basis of outline data generation, and is constituted by a hard disk or the like.

The memory 13 is a storage device for holding the dot data designated by the input unit 10 as the outline data creation target out of the dot data stored in the storage unit 12, and is composed of a memory element such as a RAM. It The memory 13 is also provided with a work memory area for storing work data in the form of a matrix while the outline data is being created.

The outline data generation unit 14 is a processing unit that generates outline data from the dot data stored in the memory 13 and outputs the outline data to the output unit 11. The outline extraction unit 140, the smoothing processing unit 141, The target segment extraction unit 142a and the control point processing unit 142b are included in the curve processing unit 142.

The contour extraction unit 140 pays attention to the grid points where the respective pixels are adjacent to each other, and by taking into account the state of each pixel surrounding the grid points, the tracking processing described later is used to store the dots stored in the memory 13. It is a processing unit that extracts contour line data consisting of straight lines based on the data and outputs the contour line data to the smoothing processing unit 141 or the curve processing unit 142.

The smoothing processing section 141 includes a contour extracting section 140.
Is a processing unit that performs a smoothing process to be described later on the extracted contour line data, and outputs the processing result to the curve processing unit 142 or the output unit 11.

The curve processing section 142 is a smoothing processing section 14.
Among the segments that make up the contour line data received from No. 1, the segment satisfying a predetermined condition is referred to as "Page Description Language POSTSCRIPT Reference Manual" (Adobe System
(Written by Matsumura, ASCII Publishing Co., 1988), and the like, and outputs the curve-shaped contour line using the Bezier function.
Is a processing unit for outputting to.

The curve processing section 142 is composed of a target segment extraction section 142a and a control point processing section 142b.

The target segment extraction unit 142a extracts a segment having a monotonous increase or decrease in the gradient of the segment forming the contour line as a curving target segment and outputs it to the control point processing unit 142b. It is a department.

The control point processing unit 142b receives the segment extracted by the target segment extraction unit 142a, obtains the control point of the Bezier curve to replace the segment with the Bezier curve, and uses the segment by using the control point. It is a processing unit that outputs the output to the output unit 11 after making a curve.

Next, the processing procedure of the outline data generator 14 having the above-mentioned configuration will be described.

FIG. 2 is a flowchart showing the processing procedure of the outline data generator 14.

As shown in FIG. 2, when an outline data creation instruction is input from the input unit 10, the outline data creation unit 14 reads the corresponding dot-format font from the storage unit 12 (step 201) and stores it in the memory. Store in 13.

Then, the contour extracting section 140 examines the data of 4 pixels surrounding the grid point of interest and extracts the contour line by repeating the process of selecting the grid point corresponding to the pattern of 4 pixels as the next grid point. Yes (Step 20)
2).

In this embodiment, when the next grid point is selected, four pixels adjacent to the current grid point are searched, but the search range is expanded to 12 pixels in the neighborhood or 16 pixels in the neighborhood. It is also possible to do so.

Next, it is confirmed whether or not the smoothing processing by the smoothing processing unit 141 is performed (step 141). If the smoothing processing is not performed, the process proceeds to step 205, whereas the smoothing processing is performed. When performing the
Outputs the contour line to the smoothing processing unit.

Then, the smoothing processing unit 141 that has received this contour line performs a straightening process to eliminate the step-like step generated in the straight line portion of the contour line (step 204).

Next, the smoothing processing unit 141 confirms whether or not to perform the curving processing by the curving processing unit 142 (step 205), and if the curving processing is not to be performed, the process proceeds to step 208. On the other hand, when performing the curve processing, the smoothed contour line is output to the curve processing unit 142.

Then, in the curving processing unit 142 that has received this contour line, the target segment extracting unit 142a extracts the segment to be curbed (step 20).
6) The control point processing unit 142b obtains the control points of the Bezier curve corresponding to the segment, curves the segment, and outputs the segment to the output unit 11 (steps 207 and 20).
8).

By performing the above series of processing, the contour line data of the dot data designated from the input section 10 is extracted from the dot data stored in the storage section 12, and the smoothing processing and the curve processing are performed as necessary. After this, the contour line data can be output as outline data.

Next, the contour line extraction process shown in step 202, the smoothing process shown in step 204, and the control point process shown in step 207 will be described in more detail using a concrete example.

FIG. 3 is a diagram showing a specific example of the contour line extraction processing (step 202) performed by the contour line extraction unit 140.

As shown in FIG. 3A, when the contour line data is extracted from the dot data "J" having a line width of 1 dot, attention is paid to the grid point located at the intersection of each dot. 0, which indicates the direction in which the grid point continues to the neighboring grid points
A value of F (hereinafter referred to as “direction value”) is obtained for each grid point, and the contour line is formed by tracing the grid points.

That is, according to the present invention, based on the idea that the outline of a font represented by dot data can be represented by the continuity of the grid points, the direction value is taken into consideration after taking into consideration the state of the adjacent pixels surrounding each grid point. Is determined and the direction value is stored in the coordinate position of the work memory W associated with the coordinate position of the grid point. Then, the contour line is extracted by tracking the direction value on the work memory W.

In the present invention, since the data possessed by the pixels adjacent to the grid point is used, it is necessary to give the dot value even outside the range of the matrix forming the dot data. Therefore, in this embodiment, the dot value "0" is given to the portion outside the matrix range.

Next, the assignment of the direction value to each grid point forming the dot data will be described.

As shown in FIG. 3B, in this embodiment,
16 direction values 0 to F corresponding to the mask patterns 30 to 3f are used.

That is, when the four pixels surrounding the grid point are all “0” as shown in the mask pattern 30, the direction value corresponding to the pixel position corresponding to the grid point in the work memory W is set. Add "0".

Similarly, if the four pixels surrounding the grid point are in any one of the mask patterns 31 to 3f, the pixel values corresponding to the grid point in the work memory W have the corresponding direction values 1 to F. Give either.

In this way, by storing the direction value at the pixel position corresponding to the grid point of the work memory W,
Work memory W composed of the direction values shown in FIG.
Is obtained.

Next, the work memory is searched, and the contour line tracking processing is performed based on the direction value of each pixel, whereby the contour line data shown in FIG. 4B can be obtained.

That is, the direction value of "8" is obtained by sequentially scanning the pixels from the pixel 4a of the work memory W shown in FIG. 4A for starting contour tracing (hereinafter referred to as "tracing start pixel"). Confirm that pixel 4b is the tracking start pixel.

The direction value of the tracking start pixel 4b is'
Since it is 8 ′, from the table shown in FIG. 3B, in this pixel, a contour line comes from below (hereinafter, referred to as “−Y direction”), and to the right (hereinafter referred to as “X direction”) .), And the pixel 4c located to the right of the current pixel.
Be the next tracking pixel.

In the same manner, the contour line data shown in FIG. 4 (b) can be obtained by performing the pixel tracking until the tracking start pixel 4a is returned.

As described above, according to the present invention, the direction value is given in consideration of the states of the pixels adjacent to the lattice point, and
By tracing the contour line based on the direction value, the contour line can be extracted even from dot data having a width of one dot.

Next, a case where the contour line is composed of a plurality of closed curves will be described.

FIG. 5 is a diagram showing a specific example of extracting contour line data from the dot data “times”.

In order to extract the contour line of the dot data "times" shown in FIG. 5A, the dot data shown in FIG.
As in the case of J ′, FIG.
By storing the direction value shown in FIG. 5B in the work memory W, the work memory W shown in FIG. 5B is obtained.

Then, by scanning the work memory W, the tracing of the contour line can be started from the tracing start pixel 5a, and one closed curve forming the contour line can be obtained.

By the way, in this specific example, since another closed curve forming the contour line exists, the scanning of a new tracking start pixel is restarted from the previous tracking start pixel 5a.

That is, the pixel 5b is selected as the next tracking start pixel and is tracked by the same procedure, whereby another closed curve can be obtained.

Similarly, the contour line shown in FIG. 5C can be obtained by performing the tracking process using the pixels 5c and 5d as the tracking start pixels.

Here, in the present embodiment, in order to prevent the duplication of tracking, each pixel tracked with the pixel 5a as the tracking start pixel is replaced with data other than 0 to F. It can also be configured to write to a new work memory when deciding.

Next, the flow of the contour line extracting process performed by the contour line extracting section 140 will be described with reference to the flowchart shown in FIG.

As shown in FIG. 6, first, the state of neighboring pixels surrounding each grid point of the dot data is taken into consideration, and the direction value corresponding to the grid point is extracted and stored in the work memory W (step 601).

Then, the work memory W is scanned and a pixel having a predetermined direction value is selected as a tracking start pixel (step 602). Then, it is confirmed whether or not the tracking start pixel exists (step 603). If the tracking start pixel exists, the tracking process is sequentially performed based on the direction value of the pixel (step 604) and the tracking starts. The processed pixel value is replaced with a value indicating processed (step 605).

At this time, if there is a memory for storing the processing result other than the work memory W, the pixel value may be cleared after the tracking processing.

The processing of steps 604 and 605 is repeated until the tracking start pixel is returned (step 606).

Then, when the tracking processing started from a certain tracking start pixel is completed, it is checked whether or not there is another tracking start pixel.

Specifically, a new tracking start pixel is searched again from the previous tracking start pixel position (step 60).
2) If the new tracking start pixel exists, the same process is performed, and if the new tracking start pixel does not exist, the process ends.

By performing the series of processes described above, the contour line can be extracted even from the dot data having a one-dot width.

Next, the smoothing processing (step 204) performed by the smoothing processing section 141 will be described using a concrete example.

FIG. 7 is an enlarged view of the line segment extracted by the contour line extracting section 140 (FIG. 7A) and a processing result of smoothing the line segment (FIG. 7B). FIG.

Since the contour line extracted by the contour line extracting section 140 is merely a trace of a boundary line, as shown in FIG. 7A, a diagonal contour line is formed stepwise. There are cases.

Therefore, in the present embodiment, the smoothing processing unit 1
41 is used to linearize a line segment formed in such a staircase shape.

That is, in this embodiment, as shown in FIG. 7A, the point sequence forming the contour extracted by the contour extracting unit 140 is a0 = (x0, y0), a1 = (x1, y
1), ~, a7 = (x7, y7) and the line segments connecting the point sequences are l0, l1, ~, l7, the start point is (x0, y0) and the end point is (x7 , Y7) and pass through the midpoints of the respective line segments 10 to 17.

Therefore, the newly provided point sequences b1 to b1
b7 is, as shown in FIG. 7B, b0 = (x0, y
0), b1 = ((x1 + x2) / 2, (y1 + y2) /
2), ~, b6 = (x7, y7).

As described above, by arranging so as to pass through the midpoint between each two points forming the point sequence, it is possible to smooth the line segment formed in a staircase pattern or the like.

Next, the processing procedure performed by the smoothing processing unit 141 will be described with reference to the flowchart shown in FIG.

As shown in FIG. 8, first, the point sequence constituting the line segment to be smoothed is held, and after the start point and the end point are fixed, the variable i is initialized (i = 1) (step 1). 801). In this example, the line segments are a0 to a.
The variable i is made to correspond to the point sequence number of the line segment (1 ≦ i ≦ n−1).

Then, it is confirmed whether or not the number of point sequences n is 3 or more (step 802). If n is less than 3, the process is terminated. Here, it is confirmed whether or not the number n of point sequences is 3 or more. When the number of point sequences is 2 or less, the line segment is not formed in a stepped shape, so the smoothing process is performed. This is because it is configured so as not to perform.

On the other hand, if it is confirmed that the number of point sequences n is 3 or more, then bi = ((xi + xi + 1) / 2, (yi + yi
+1) / 2) is used to calculate the end point bi of each line segment and increment the variable i (i = i + 1) (step 803).

The variable i is smaller than n-2 (i
> N-2), the process proceeds to step 803 and the above process is repeated (step 804), and the variable i is n.
If it becomes -2 (i = n-2), b0 = (x0, y0), bn-1 = (xn, yn), and after the start point and the end point are confirmed (step 805).
The process ends.

By performing the above-described series of processing, it is possible to smooth and straighten the line segment in the case where the line segment is formed stepwise.

Next, the curve processing (step 206 to step 207) performed by the curve processing section 142 will be described in detail.

FIG. 9 is an enlarged view of a part of the contour line smoothed by the smoothing processing unit 141.

As shown in FIG. 9A, the starting point (x0, y
If there is a line segment consisting of a point sequence from (0) to the end point (xn, yn), the curving processing unit 142 replaces the point sequence with a Bezier curve control point.

Specifically, first, the target segment extraction unit 1
42a is a continuous segment, the X coordinate value is monotonically increasing or monotonically decreasing, the Y coordinate value is also monotonically increasing or monotonically decreasing, and the slope of each segment is monotonically increasing or monotonically decreasing. Extract as an object to be converted.

For example, in the case of FIG. 9A, assuming that the coordinate origin is located at the upper left corner, the X coordinate value at the end point of each segment, that is, x0, x1, x2, x3, x4,
xn successively and monotonically increases, and the Y coordinate values at the end points, that is, y0, y1, y2, y3, y4, and yn, also monotonically increase.

The inclination of each segment, that is, segment ((x0, y0)-(x1, y1)), segment ((x1, y1)-(x2, y2)), segment ((x2, y2)-( (3, x3, y3)), the segment ((x3, y3)-(x4, y4)) and the segment ((x4, y4)-(xn, yn)) also increase monotonically, so that FIG. a)
The series of segments shown in () are to be curved.

It is to be noted that the condition for the curve formation is that the X coordinate and the Y coordinate at the end points of the segments are monotonically increasing or monotonously decreasing, and the inclination of each segment is monotonically increasing or monotonically decreasing. As long as the coordinate value and the Y coordinate value are monotonic, the start point (x0,
y0) to P to end points (xn, yn), as long as each segment is within the triangle and the inclination of each segment is monotonous, the contour line does not wavy within the triangle.
This is because this continuous segment can be easily replaced with a Bezier curve.

Further, the control point processing unit 142b calculates control points corresponding to the series of segments extracted by the target segment extraction unit 142a, and curves them.

For example, in the case of the segment shown in FIG. 9A, the start point is (x0, y0) and the end point is (xn, yn).
Then, the control points are replaced with Bezier curves of (s1, y0) and (xn, t1) (FIG. 9 (b)). In addition, this s
1 and t1 are calculated based on the ratio of the slope of the straight line and the slope of the triangle.

Next, the calculation procedure of s1 and t1 will be described by catching two extreme cases. In the following, the coordinates of the control points are indicated by capital letters X and Y.

First, as shown in FIG. 10A, when the inclination of the segment is in the X-axis direction, Y0 = Y1 = Y
Since 2 = Y3, the start point of the segment (X0, Y0)
And the end points (X3, Y3) can be used to represent the segment (provided that X1 = X2 = X3).

Here, paying attention to X1, the distance X1-X0 from X1 to X0 is the distance X3-X from X3 to X0.
Since it is equal to 0, it is assumed that the length of X1 is 1.00 (100%) as compared with X3.

As shown in FIG. 10B, when the segment inclination is in the end point (X3, Y3) direction,
Since X0 can be represented by X1, it is assumed that the length of X1 is 0.00 (0%) as compared with X3.

Therefore, this X1 is set to 0 (X1 = X0)
To 1 (X1 = X3), and similarly for Y1 from 0 to 1, a curve can be expressed.

That is, the control point processing unit 142b controls by proportional calculation from the inclinations of the segments affecting the X-axis direction and the Y-axis direction and the inclinations of the triangles including the segments with reference to the extremes described above. Dot X
The coordinates and Y coordinates are calculated.

Next, the control point calculation process performed by the control point processing unit 142b will be described in more detail using a specific example.

FIG. 11 is a diagram showing a case where control points are calculated from two monotonically increasing segments and are made into curves.

As shown in FIG. 11A, the starting point (0,
When there is a segment 1 from 0) to the end point (7, 1) and a segment m from the start point (7, 1) to the end point (8, 10), the length of the triangle in the X direction (X) = 8 The length of the triangle in the Y direction (Y) = 10, and the inclination of the hypotenuse of the triangle in the X direction (Xd) = 10 /
Therefore, the gradient Xd becomes the threshold value in the X direction.

Then, since the segments below this slope affect the curve, when the slopes of the segments 1 and m in the X direction are respectively calculated, the slope of the segment l (lx) = 1/7 The slope of the segment m (mx) = 9/1.

That is, in the X direction, the segment l
Therefore, the coordinates of X1 are: X1 = (X3-X0) * (1-lx / Xd) = 8 * {1- (1/7) (10/8)} = 216/35 Becomes

Similarly, the inclination (Yd) in the Y direction of the hypotenuse of the triangle = 8/1
Since 0 is a threshold value and the gradient (ly) of the segment 1 is 7/1 and the gradient (my) of the segment m is 1/9, it can be seen that the segment m affects the Y direction.

Therefore, the coordinates of Y1 are Y1 = (Y3−Y0) × (my / Yd) = 10 × (5/36) = 25/18.

Therefore, the coordinate values of the start point, the end point, and the two control points of the Bezier curve in this case are (0, 0),
(216 / 35,0), (8,25 / 18), (8,1)
0), and the segment is replaced by the curve shown in FIG. 11 (b).

Next, the case where the contour line segment composed of four segments is replaced with a curve will be described.

FIG. 12 is a diagram showing a case where control points are calculated from four monotonically increasing segments and are made into curves.

As shown in FIG. 12A, the start point (0,
Segment a from 0) to end point (3,1), segment b from start point (3,1) to end point (5,2),
Segment c from start point (5,2) to end point (6,4)
And a segment d from the start point (6, 4) to the end point (8, 10), the length of the triangle in the X direction (X) = 8 the length of the triangle in the Y direction (Y) = 10 and the inclination (Xd) of the hypotenuse of the triangle in the X direction = 10 /
Therefore, the gradient Xd becomes the threshold value in the X direction.

Then, since a segment having a slope less than this influences the curve, X of the segments a, b, c and d is
The inclinations of the respective directions are calculated as follows: inclination of segment a (ax) = 1/3 inclination of segment b (bx) = 1/2 inclination of segment c (cx) = 2/1 inclination of segment d (dx) = 6 It becomes / 2.

That is, in the X direction, the segment a
And segment b has an effect, so X
The coordinates of 1 are: X1 = (X3-X0) * (1-ax / Xd) * (1-b
x / Xd) = 8 * {1- (4/15)} * {1- (2/5)} = 264/75.

Similarly, the inclination (Yd) of the hypotenuse of the triangle in the Y direction = 8/1
0 is the threshold value, and the gradient of segment a (ay) = 3/1 the gradient of segment b (by) = 2/1 the gradient of segment c (cy) = 1/2 the gradient of segment d (dy) = Since it is 2/6, it can be seen that the segment c and the segment d influence in the Y direction.

Therefore, the coordinates of Y1 are as follows: Y1 = (Y3-Y0) * (cy / Yd) * (dy / Y
d) = 10 × (5/8) × (5/12) = 125/48.

Therefore, the coordinate values of the start point, the end point and the two control points of the Bezier curve in this case are (0, 0),
(264 / 75,0), (8,125 / 48), (8,
10) and the segment is replaced by the curve shown in FIG.

Next, the processing procedure performed by the control point processing unit 142b will be described with reference to the flowchart shown in FIG.

As shown in FIG. 13, first, in order to determine the segment that affects the curve, the threshold value Xd of the tilt in the X direction and the threshold value Yd of the tilt in the Y direction are obtained, and n segments are calculated. (Segment 10 to Segment ln-1) is set (i = 0) (step 130
1).

At this time, Xd and Yd are calculated by Xd = Y / X Yd = X / Y, and lj = {(xj, yj)-(xj + 1, yj + 1) for each segment. } (Where 0 ≦ j ≦ n−1).

Next, the inclination of each segment with respect to the X and Y directions is obtained (steps 1302 to 13).
03).

At this time, the inclination l of the segment li in the X direction
The tilt liy in the ix and Y directions can be obtained by lix = (yi + 1−yi) / (xi + 1−xi) liy = (xi + 1−xi) / (yi + 1−yi).

Next, for each segment, step 1
Inclination lix and Y in the X direction of the segment obtained in 302
It is confirmed whether or not the inclination liy in the direction is smaller than the threshold values Xd and Yd obtained in step 1301, respectively, and the segment having the inclination smaller than the threshold value is considered to affect the curve and is held. (Step 1305
~ Step 1308).

Then, the coordinate positions X1 and Y2 of the control point are calculated from the inclination of the segment held in step 1308 and the threshold value (step 1309).

By performing the above series of processing, it is possible to easily obtain the coordinate position of the control point when the series of segments is curved.

As described above, in the present embodiment, the contour extraction unit 140 focuses on the grid point of the dot data, stores the direction value by the value of the four pixels which are in contact with the grid point, and The contour line data can be generated from the character data in the dot format in which the dot width is represented by 1 or more.

Further, since the smoothing processing unit 141 is configured to connect the respective midpoints of the plurality of segments to smooth the contour line, it is possible to improve the quality of the contour line.

Furthermore, the curve-processing section 142 selects one of the smoothed continuous segments whose X-coordinate value and Y-coordinate value monotonically increase or monotonically decrease, and whose inclination of each segment monotonically decreases or monotonically increases. Since it is configured to replace the continuous segment with a Bezier curve having two control points based on the coordinate values of the start point and the end point of the continuous segment, the segment composed of the linear component is converted into the Bezier curve. Can be replaced.

In this embodiment, the contour line extracting section 140
The case where the smoothing processing unit 141 smoothes the contour line extracted by the above and the curve processing unit 142 further curves is described, but the present invention is not limited to this, and each processing is performed. The parts can also be processed independently.

[0133]

As described above in detail, in the present invention, the direction in which the contour lines are connected at each grid point is determined in correspondence with the values of the four adjacent pixels, and the directionality of each grid point is determined. Since the grid points are traced based on this to extract the contour line data, it is possible to extract the outline data even from a line segment having a one-dot width.

Further, in the present invention, in the case of continuous segments, the X coordinate value at the end point of each segment monotonically increases or decreases, and the Y coordinate value at the end point monotonically increases or decreases monotonically. A plurality of segments whose slopes are monotonically increasing or monotonically decreasing are detected as segments to be curved, and based on the coordinate values of the start and end points of the detected continuous segments and the slope of each segment, the continuous Since the segment to be converted is replaced with the Bezier curve having two control points, it is possible to efficiently obtain high-quality outline data.

Further, according to the present invention, since continuous segments are replaced with new segments in which the midpoints of the respective segments are connected, it is possible to efficiently improve the quality of the contour line data. is there.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an outline data generation device according to the present invention.

FIG. 2 is a flowchart showing a processing procedure of an outline data generation unit shown in FIG.

FIG. 3 is a diagram showing dot data processed by a contour line extraction unit shown in FIG. 1 and a mask pattern used for the processing.

FIG. 4 is a diagram showing a processing result obtained by performing contour line extraction processing on the dot data shown in FIG. 3;

5A and 5B are diagrams showing another dot data processed by the contour extraction unit shown in FIG. 1 and a processing result.

6 is a flowchart showing a processing procedure performed by a contour line extraction unit shown in FIG.

FIG. 7 is a diagram showing polygonal line data processed by a smoothing processing unit shown in FIG. 1 and a smoothing processing result.

8 is a flowchart showing a processing procedure performed by a smoothing processing unit shown in FIG.

9 is a diagram showing a series of segments processed by the curving processing unit shown in FIG. 1 and control points generated after the processing.

FIG. 10 is a diagram showing an extreme case in which the curving processing unit shown in FIG. 1 performs curving.

FIG. 11 is a diagram showing a specific example of processing performed by the curve processing unit shown in FIG. 1.

FIG. 12 is a diagram showing another specific example processed by the curving processing unit shown in FIG. 1.

FIG. 13 is a flowchart showing a processing procedure performed by a curve processing unit shown in FIG.

[Explanation of symbols]

10 input unit, 11 output unit, 12 storage unit, 1
3 memory, 14 outline data generation unit, 14
0 contour extraction unit, 141 smoothing processing unit, 142 curve processing unit, 142a target segment extraction unit, 14
2b Control point processing unit

Claims (3)

[Claims] 1. An outline generation device for generating contour line data composed of a plurality of segments from image information in a dot format formed by arranging a plurality of pixels, wherein each grid is located at a contact point of four adjacent pixels. Contour extraction means for obtaining the contour line continuation direction at a point corresponding to the values of the four pixels, tracing the contour line based on the contour line continuation direction of each grid point, and extracting the contour line data. An outline data generation device characterized by being provided. 2. A plurality of segments forming a contour line, which are continuous segments, in which the X coordinate value at the end point of each segment monotonically increases or decreases and the Y coordinate value at the end point monotonically increases or decreases. A monotonically decreasing, further detecting means for detecting a plurality of segments in which the inclination of each segment monotonically increases or monotonically decreases, based on the coordinate values of the start and end points of consecutive segments detected by the detecting means and the inclination of each segment. And a curve forming means for replacing the continuous segment with a Bezier curve having two control points. 3. An outline generation device for generating contour line data consisting of a plurality of segments from dot-form image information formed by arranging a plurality of pixels, wherein each grid is located at a contact point of four adjacent pixels. A contour extracting means for obtaining a contour line continuation direction at a point corresponding to the values of the four pixels, tracing the contour line based on the contour line continuation direction of each grid point, and extracting contour line data. A smoothing unit that replaces the continuous segment extracted by the contour extracting unit with a new segment that connects the midpoints of the segments, and a continuous segment among a plurality of segments that form the contour line. X at the end point of each segment
Detecting means for detecting a plurality of segments whose coordinate values monotonously increase or monotonically decrease, Y coordinate values at the end points monotonically increase or monotonically decrease, and the inclination of each segment monotonically increases or monotonically decreases; And a curve forming means for replacing the continuous segment with a Bezier curve having two control points on the basis of the coordinate values of the start point and the end point of the continuous segment detected by the above and the inclination of each segment. Outline data generation device.