JP2521756B2 - Pattern data generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a method of restoring compressed data in which a contour of a pattern is approximated by straight lines and curved lines, a means for controlling a stroke line width in which vertical / horizontal lines and curved strokes are integrated, / It is characterized in that a means for correcting the waviness of the horizontal line is provided.

[Industrial applications]

 The present invention relates to a pattern data generation device.

When characters and figures are stored in a dot pattern, there are problems such as a large memory capacity and difficulty in enlarging and reducing. In this respect, the method developed by the present inventors for approximating the contours of a character or graphic pattern by a straight line and a curve and storing the character or graphic with a vector representing the straight line and a function representing the curve requires a large amount of data compression. It is possible, and it is easy to enlarge and reduce the display of characters and figures.

[Conventional technology]

The present inventors have proposed various pattern data compression methods for approximating the contours of this character or figure pattern by using straight lines and curved lines. A. "Pattern data compression method" (Japanese Patent Application No. 61-118920), B "pattern compression method by curve approximation" (Japanese Patent Application No. 61-220400), C "curve approximation interval setting method" and the like are a few examples. As a method for reproducing characters and figures from this compressed data, D "Compressed data restoration and generation method" (Japanese Patent Application No. 61-139646) and "Pattern line width control method" are proposed.

The problem with the method of reproducing characters and figures from the above compressed data is that the generation of a curved stroke that connects smoothly to a vertical / horizontal line is performed by the linear approximation of the vertical / horizontal line and the curved approximation of the curved stroke. At the point of connection of the vertical / horizontal line and the curved stroke, the continuity of the position is guaranteed, but the continuity of the derivative is not guaranteed, and thus lack of smoothness. Invention B improves on this point. The vertical / horizontal lines and the curved strokes are integrated with respect to the curved strokes that are smoothly connected to the vertical / horizontal lines of the characters and figures, and the integrated strokes are converted by the B-spline function. To approximate. Since the first derivative and the like are continuous in the same function, the smoothing of the connecting portion between the vertical / horizontal line reproduced from the compressed data and the curved stroke is eliminated by the above processing.

When reproducing characters and figures from compressed data, it is possible to specify the line width, such as the number of vertical / horizontal lines. In the conventional method, if this line width control is performed on vertical / horizontal lines and curved strokes that smoothly connect to them, the line width is independently translated for vertical / horizontal lines and linear conversion is performed for curved strokes. Because of this, only positional continuity is guaranteed at the connection points of the vertical / horizontal lines and the curved strokes. In this respect, in the spline function display for the integrated stroke as in the invention A, the same line width control can be performed for the vertical / horizontal lines and the curved stroke, and continuity in the derivative is also guaranteed.

[Problems to be solved by the invention]

However, when the integrated stroke is reproduced with the compressed data according to the invention A, waviness may occur in vertical / horizontal lines. This is a small one, and one dot protrudes in the width direction.
Although it retreats, it is not preferable that the contour of the vertical / horizontal line, which should be a straight line, be uneven.

The present invention intends to improve these points and enable generation of high quality character and graphic patterns from the compressed data.

[Means for solving problems]

FIG. 1 shows the principle of the device of the present invention. 10 is the invention A
It is the compressed data of the integrated stroke by. When the vertical / horizontal line width of characters and figures is specified as n dots,
There are two ways to specify the reduction ratio.
At 14, the latter is performed by the line width calculation unit 12. A line width control unit 16 receives the line width calculation value 12 and the line width instruction value from the line width giving unit 14. Reference numeral 18 is a polynomial in this example, a linear conversion unit for the B-spline function, and 20 is a function value calculation unit. Reference numeral 22 is a contour restoration portion of a curved portion, that is, a restoration portion of the curved stroke, and reference numeral 24 is a contour restoration portion of a straight portion smoothly connected to the curved stroke.

[Action]

The two contour lines (on both sides) of the integrated stroke are approximated by the B-spline function shown in equation (1).

However, n _t is the number of nodes, Cj is a coefficient, Nj, ₄ is the difference quotient (base function) of the fourth order, and the compressed data 10 is composed of the coordinate values of the nodes and the coefficient Cj of the B-spline function. The polynomial linear conversion unit 18 linearly converts the coordinate value of the node and the coefficient Cj according to the size of the generation pattern. Taking the vertical / horizontal line in Fig. 2 and the right contour line of a curved stroke that smoothly connects to it as an example, the nodes of this integrated stroke are Z1, Z2, and Z3. If line width control is not performed, these nodes The Y coordinate values y ₁ , y ₂ , y ₃ and the coefficient Cj are multiplied by the magnification (αx, αy). These αx and αy are equal to the scaling factor β of the scaling conversion. The conversion formula is shown in formula (2).

This processing corresponds to processing for converting the y-axis and S (y) -axis scales as shown in FIG. 4th with this linear transformation
As shown in the figure, the spline curve of the enlarged / reduced generated pattern can be calculated, and the contact points Z1 'to Z3' corresponding to the nodes Z1 to Z3 before generation can also be obtained.

Each coordinate value (y _j ′, S (y) ′) obtained by the above equation (2)
The "compressed data decompression and generation method" can be used to obtain the contour points of the integrated stroke from the above, but this may cause undulations in the vertical / horizontal line portions as shown in FIG. 5 (a). (This figure is exaggerated).

Therefore, in the present invention, the contour restoration of the curved portion and the contour restoration of the straight portion are separated. Then, the restoration is started from the node Z3 ′, is performed by the spline function up to Z2 ′, and Z2 ′ to Z
Draw a straight line by DDA (Digital Differencitial Analyzer) up to 1 '. In this way, no waviness occurs in the vertical / horizontal lines.

When controlling the line width of the integrated stroke, the procedure is as follows. It is assumed that the line widths of the vertical / horizontal lines are determined and that the nodes Z1 and Z2 in FIG. 2 are located at Z1 ″ and Z2 ″ on the generated pattern. For the calculation of Z1 ″ and Z2 ″, “a character pattern enlarging / reducing method with a line width control function and a“ pattern similarity conversion method (Japanese Patent Application No. 60-6166) can be used. For the end point Z3 of the integrated stroke, , Multiply by the scaling factor β and Z
Find 3 ″. This Z1 ″ (x1 ″, y1 ″), Z2 ″ (x2 ″, y
From 2 ") and Z3" (x3 ", y3"), the linear conversion corresponding to the above equation (2) is performed by the following equation (3).

Each coordinate value (yj ″, S obtained by the above equation (3)
In order to obtain the contour point of the integrated stroke from (y _j ″) ″), the “compression data decompression / generation method” can be used.

Since waviness may occur in the vertical / horizontal lines as in the case where the line width is not controlled here, the vertical / horizontal lines are drawn with DDA to remove the waviness and generate a high quality integrated stroke.

〔Example〕

FIG. 6 shows a character pattern generation block diagram according to an embodiment of the present invention. The compressed data 10 includes vertical / horizontal lines, bending points obtained by linearly approximating the contour of a decoration and its attribute data, and coefficients and nodes obtained by approximating diagonal lines / curve strokes by a B-spline function and vertical / horizontal lines and curved strokes. It is composed of attributes and the like indicating an integrated stroke. Here, the contour restoration of the integrated stroke of the vertical / horizontal lines and the curved stroke is performed by using the present invention, and for the other contours, for example, the above-mentioned "compression data restoration and generation method" is used. Below,
The processing of each block will be briefly described.

First, the line width giving unit 14 arbitrarily sets the line width of the vertical / horizontal lines after conversion, as described above. When the line width after conversion is proportional to the enlargement / reduction ratio with respect to the line width before conversion, the above process is not performed, and the line width calculation unit 12 performs the enlargement / reduction conversion magnification and the vertical / before conversion. The line width of the vertical / horizontal line after conversion from the horizontal line is calculated. For this purpose, for example, the above-mentioned invention "enlargement / reduction system of character pattern having line width control function" can be used. Since the line width control unit 16 sets the line width of the vertical / horizontal lines after conversion to the line width of the vertical / horizontal lines determined by the line width calculation unit 12 or the line width assignment unit 14, the line width control units 16 are positioned on the vertical / horizontal lines. Control the coordinate value after conversion of each bending point. The same is done for the integrated stroke, and the coordinate value of the bending point of the vertical / horizontal line portion is used. For this, for example, the invention “pattern similarity conversion method” can be used. The bending point linear conversion unit 32 enlarges / reduces the coordinates of the bending points belonging to the vertical / horizontal line and the ornament, and obtains the coordinates of the converted bending points. Then, a straight line is generated by DDA between each bending point, and the vertical / horizontal lines and the contour of the ornament are restored. The contour restoration (18, 20, 22, 24) of the integrated stroke is performed by the present invention. To restore the contours of the slanted lines / strokes, the polynomial linear transformation unit 26 performs the linear transformation according to the equation (2), and then the calculation unit 28 calculates the function value and the restoration unit 30 restores the contours. In this way, the contours of vertical / horizontal lines, ornaments, integrated strokes, and diagonal / curved strokes are restored to obtain the entire contour of the pattern. The contour connecting unit 36 connects the contours obtained. The filling section 38 fills the inside of the entire contour. This internal filling process is performed by defining the determination points that are the start point and the end point of the filling and filling between the determination points. For this filling processing, for example, "polygonal internal area filling method" (Japanese Patent Application No. 60-48896) can be used.

7 and 8 show examples of line width control. FIG. 7 is a reproduced character according to the method of the present invention, and FIG. 8 is a reproduced character according to the conventional method. In both cases, (a) is a line width calculation and (b) is a line width control example by giving a line width. With the conventional method, it is not possible to generate a high-quality curved stroke that smoothly connects with a vertical / horizontal line, but the present invention generates a high-quality pattern of continuous derivatives at the connection point of a vertical / horizontal line and a curved stroke. be able to.

〔The invention's effect〕

As described above, according to the present invention, by using the compressed data according to the invention A, it is possible to generate a vertical / horizontal line portion having no undulation, and a curved stroke smoothly connected to the vertical / horizontal line portion even if line width control is performed. It is very effective.

[Brief description of drawings]

 FIG. 1 is a block diagram of the principle of the device of the present invention, FIG. 2 is an explanatory diagram of an integrated stroke, FIGS. 3 and 4 are explanatory diagrams of enlargement / reduction, FIG. FIG. 7 is a block diagram showing an embodiment of the invention, FIG. 7 is a diagram showing an example of line width control according to the present invention, and FIG. 8 is a diagram showing an example of line width control according to a conventional method.

Claims (1)

(57) [Claims] 1. A pattern in which vertical / horizontal lines of a character or a figure and curved strokes smoothly connected thereto are integrated and a character or figure pattern is generated from pattern data including compressed data obtained by approximating the integrated stroke as a whole by a sprite function. In the data generation device, the line width control means (12, 14, 16) for controlling the vertical / horizontal line to a line width based on the designation, and the line width control means for outputting the vertical / horizontal line width from the line width control means Means (18, 20) for linearly converting the spline function approximating the integrated stroke, and means (22) for restoring the curved portion contour of the integrated stroke by the linear conversion output of the spline function from the linear conversion means.
Then, a straight line portion is generated by DDA following the restored curved portion,
Straight line contour restoring means for generating a straight line portion without waviness (2
4) A pattern data generation device comprising: