JPH0777968A - Method and device for character generation - Google Patents

Abstract

PURPOSE:To store and reproduce plural fonts, etc., by an easy method by storing the shape of a solid body whose section show character shapes of another font when the solid body is cut with plural planes and cutting the solid body with a cutting surface corresponding to a desired font. CONSTITUTION:When a character I is represented in three dimensions, the character is cut with a plane perpendicular to a Z axis. A space area (0<=X<=15, 0<=y<=15, and 0<=z<=15) including this solid body is divided into 15X15X15 elements with three-dimensional lattices (of 1 in unit length) and stored in a memory in a character generator so that the ratio of the volume by which the solid body occupies each element to the element volume, i.e., a volume rate can be reproduced. The character shape can be reproduced with a volume rate distribution on an eight lattice surface from the bottom when this solid body is cut with a plane of Z=7.5. Assuming that the values of a volume rate function F at points (x) and (y) are defined matching the volume rate of an element in its center, the values of F at other points are bi-linear interpolated to obtain the outline of the character I with a contour of F=0.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a character generating method and device for generating a font pattern of characters used for displaying or printing.

[0002]

2. Description of the Related Art In order to print a character as an output of an information processing device such as a computer or a word processor, the shape (font pattern) of the character is stored in a memory in advance, and is reproduced in a human-readable form at the time of output. There is a need to. Regarding the shape of the character, the character itself may be engraved on the printing hammer on the side of the printing device, or may be stored as digital information in the processing device or the printing device. Examples of the former include hammer-type printers for large-scale computers and daisy-wheel printers for personal computers, and examples of the latter include dot-matrix impact printers, thermal transfer printers, inkjet printers, and electrophotography. There are laser beam printers, etc. depending on the method.

Compared with the former method, the latter method has the advantage that many kinds of character typefaces (fonts) can be selected without replacing the print head and the output of figures and the like can be easily performed. Is becoming.

Conventionally, as a method of digitally storing a character shape, a method of storing a skeleton of a character (vector font), a method of storing a character as a binary image as a dot matrix (dot font), and a contour are stored. The method (outline font or scalable font) has been used. Dot fonts are mainly used to represent small and medium characters on medium and low resolution printers, vector fonts are mainly used on pen plotters, and outline fonts are mainly used on high resolution printers. .

In order to handle a plurality of character fonts by these methods, it is basically necessary to store shape data separately for each font. However, a simple method may be used in which an italic font is expressed by inclining the shape of an upright font. In this case, the degree of tilt can be arbitrarily specified.

[0006]

However, according to the conventional method, it is difficult to express an intermediate typeface between two types of typefaces, except for the case of a simple italic typeface and the like.

Therefore, an object of the present invention is to provide a character generating method and apparatus capable of storing / reproducing a plurality of typefaces and intermediate typefaces by a simple method.

[0008]

In order to achieve such an object, the invention of claim 1 is such that when a solid is cut into a plurality of planes, each cross section represents a character shape of a different typeface. Store the shape of the solid in memory,
When a character is generated, the character shape is obtained by performing image processing for cutting the solid body with a cut surface corresponding to a desired typeface.

The invention of claim 2 is characterized in that a plurality of typefaces are expressed by cutting the solid body in planes parallel to each other.

Furthermore, the invention of claim 3 stores a plurality of typefaces as a solid in which the character shape on the cut surface also changes continuously when the way of cutting the solid is continuously changed. Is characterized by.

Still further, according to the invention of claim 4, the space containing the solid is divided into a plurality of elements by a lattice, and the solid in the form of a volume ratio showing a ratio of the volume occupied by the solid to the element volume in each element. It is characterized by storing the shape of.

Furthermore, the invention of claim 5 is characterized in that a part of the element dividing grid is subdivided.

Furthermore, the invention of claim 6 is characterized in that the value of the volume ratio is given to the center, on the surface, on the side, on the grid point, or on a combination thereof and stored.

Furthermore, the invention of claim 7 is characterized in that diffusion processing is performed on the value of the volume ratio before obtaining the distribution of the volume ratio.

Furthermore, the invention of claim 8 is characterized in that the volume ratio is interpolated by an interpolation method of linear interpolation, class C3 cubic interpolation, Lagrange interpolation or spline interpolation, and the solid is represented by the interpolation. Characterize.

Furthermore, the invention of claim 9 finds a place where the value of the volume ratio takes a predetermined value on the side of the element, and finds the contour of the solid by connecting the places,
It is characterized in that the character-shaped portion having the volume ratio equal to or larger than a predetermined value is printed based on the contour.

Further, the invention of claim 10 is characterized in that, in an element including an end portion of a character stroke, a character contour is obtained by extrapolating a character contour in an adjacent element.

Furthermore, the invention of claim 11 is characterized in that the shape of the surface of the solid is stored as the shape of the solid.

Furthermore, the invention of claim 12 is characterized in that the surface shape of the solid is represented by a curved surface by a piecewise polynomial.

Still further, according to the invention of claim 13, a storage means for storing the shape of the solid body such that each cross-section when the solid body is cut by a plurality of planes represents a character shape of a different typeface, and a character. The image processing means obtains a character shape by performing image processing for cutting the solid body at a cut surface corresponding to a desired typeface when the character is generated.

[0021]

In the present invention, a solid body whose cross-sections when cut along a plurality of planes represent the character shapes in different typefaces is considered, and the shape of the solid body is stored in a memory, so Remember the shape. At the time of reproduction, that is, at the time of character generation, a character shape is obtained by cutting a solid body at a cut surface corresponding to a desired typeface.

The easiest way to cut a solid is to cut in planes parallel to each other. In order to represent an intermediate typeface, it is desirable to store a plurality of typefaces as a solid type in which the character shape on the cut surface changes continuously when the cutting method of the solid type is continuously changed.

One method of storing the three-dimensional shape is to divide a space containing the three-dimensional shape into a plurality of elements by a grid and store the ratio (volume ratio) of the volume occupied by the three-dimensional shape in each element. . In this case, the element division grid is subdivided as necessary. The volume ratio value is the element center, on the surface,
It can be given and stored on a side, on a grid point, or a combination thereof. At the time of reproduction, the volume ratio is interpolated by linear interpolation, class C3 cubic interpolation, Lagrangian interpolation, spline interpolation, or the like, and a solid can be reproduced at a portion where the volume ratio is a predetermined value or more. Alternatively, it is also possible to find a place where the value of the volume ratio has a predetermined value on the side of the element, connect it to obtain the contour of the solid body, and obtain a portion where the volume ratio is the predetermined value or more based on it.

Another method of storing the three-dimensional shape is to store the surface shape of the three-dimensional shape. A typical surface shape storage method is a curved surface representation using a piecewise polynomial. Examples include spline surfaces, Bezier
Curved surface, Overhauser curved surface, etc.

[0025]

Embodiments of the present invention will now be described in detail with reference to the drawings.

<First Embodiment> FIG. 1 is a diagram showing a method of representing a character I as a solid in the first embodiment of the present invention. In the present embodiment, the shape of the letter I is obtained by cutting along the plane perpendicular to the z-axis, and the cutting plane is continuously moved in parallel (corresponding to the invention of claims 2 and 3), thereby The length of the horizontal bar of is continuously changed to obtain various different typefaces.

A spatial region containing this solid (0≤x≤15,
0 ≦ y ≦ 15, 0 ≦ z ≦ 15) is divided into elements by a 15 × 15 × 15 cubic lattice (unit length 1), and the ratio of the volume occupied by the solid in each element to the element volume, that is, the volume ratio (volume ratio (Corresponding to the invention of claim 4) is stored in a memory in the character generator so that it can be reproduced. This solid is z
The character shape when cut on the plane of = 7.5 can be reproduced by the volume ratio distribution as shown in FIG. 2 in the eighth lattice plane from the bottom. Considering that the value of the volume ratio function F at the point (x, y) is defined to match the volume ratio of the element at the center of each element, the value of F at the other point is bilinearly interpolated, When the contour line of F = 0.5 is drawn, the contour of the character I is obtained as shown in FIG.

In order to print this character in the dot matrix type printer, a dot (dot) may be printed using the data in the region of F ≧ 0.5. This method seems to be similar to the binarization method in so-called multi-valued image processing in which an image with gradation is stored and reproduced as a multi-valued image, but the original image has a clear contour with two gradations. The processing is completely different because it is limited to the character shape that it has. Normal,
In multi-valued image processing, elements above the threshold value are set to F = 1, and elements below the threshold value are set to F = 0, and the position of the contour within the element is not searched. The reason is that in the multi-valued image processing, even if the density distribution as shown in FIG. 2 is given, the original image may have a clear contour like a character or a smooth gradation. This is because it is impossible to know more than the resolution (element size).

8 to store the value of F in the element
When an integer value G (0 to 255) of bits is used (G = 2
55 is regarded as F = 1.0), and the representation accuracy of the position of the outline of the character is about 1/255 of the element size. on the other hand,
When an element is subdivided using twice the storage capacity (16 bits) and a character is represented by a binary dot matrix, each element is divided into a 4 × 4 sub-matrix, so the position of the outline of the character The expression precision of is 1 / element size
It will be about 4. That is, when this method is used, it is possible to express a character with higher accuracy with a small storage capacity. In addition, according to this method, it is possible to freely enlarge or reduce the typeface.

FIG. 4 is a block diagram of a dot matrix type printing apparatus having a character generator using the method of this embodiment.

In FIG. 4, the external interface 2 receives a print command for designating a printing operation and a character code indicating a character to be printed from the information generation source. The control unit 1 is mainly a CP
It is composed of a U (central processing unit) and controls the printing operation. The control unit 1 also constitutes a part of a character generator 100 that generates a font pattern from a character code. The control relating to character generation in another embodiment described later is executed by the control unit 1. Further, the linear interpolation calculator 5 executes a calculation process, which will be described later, relating to the generation of the font pattern. Print information corresponding to the created font pattern is sent to the print head 6, and the print head 6 records on the recording paper. Controller 1 and linear interpolation calculator 5
Operates as the image processing means of claim 13.

A character font ROM (read-only memory-memory according to the first aspect of the invention, storage means according to the thirteenth aspect of the invention) 3 stores a font pattern relating to the present invention and corresponding to a normal character code. The external character registration RAM (random access memory) 4 stores a font pattern corresponding to a character code for external character registration.

In such a configuration, when the print command is received through the external interface 2, the control unit 1 receives the character shape data (volume ratio of each element) from the character font ROM 3 or the external character registration RAM 4 according to the typeface and the character code. Is represented by 8 bits), the above-mentioned F value corresponding to each print dot is calculated in the linear interpolation calculation circuit 5, and when F ≧ 0.5 (G ≧ 128), the print head 6 is driven. Then, the corresponding print dots are hit by the print head 6. These processes are controlled by the control unit 1.

The storage method of the volume ratio F is not limited to the 8-bit fixed point method, but an arbitrary bit length can be used according to the required precision, and the floating point method (divided into the exponent part and the mantissa part). May be stored by other methods).

<Second Embodiment> In the second embodiment of the present invention, in order to store the three-dimensional shape of FIG. 1, the volume ratio value is not the center of the element but the vertex of the element (lattice point-claim). 6 of the invention, on the surface of the other elements, on the sides, on the sides, and combinations thereof are also possible). When the volume ratio distribution at z = 7.5 is obtained as the average of the lattice points at z = 7 and z = 8, the result is as shown in FIG. Based on this value, F = 0.
When the contour line of 5 is obtained by linear interpolation, a character shape as shown in FIG. 6 is obtained.

In FIGS. 3 and 6, the contour is not smooth at the end of the character stroke, but a smooth contour can be obtained by using a high-order interpolation polynomial. For example, in FIG. 7, the value of the volume ratio function F (x, y) at the point (x, y) in the central element (hatched portion) is
Interpolation using Overhauser's piecewise cubic polynomial, which is a C1 class function,

[0037]

[Equation 1]

[0038] Here, (x, y) is the local Cartesian coordinates (0 ≦ x ≦ 1, 0 ≦ y ≦ 1), F _ij is the value of F at the vertex ij, E0, E1, E2, and E3 are the following expressions,

[0039]

[Equation 2] E ₀ (x) = − 0.5x + x ² −0.5x ³

[0040]

[Equation 3] E ₁ (x) = 1-2.5x ² + 1.5x ³

[0041]

[Equation 4] E ₂ (x) = 0.5x + 2x ² −1.5x ³

[0042]

## EQU5 ## The interpolation function given by E ₃ (x) =-0.5x ² + 0.5x ³ . When the contour line of F = 0.5 is displayed by this method, a smooth contour is obtained as shown in FIG. As the form of the interpolation function, other than the expressions (Expression 2 to Expression 5), for example, another C1 class piecewise cubic polynomial, Lagrange polynomial, spline function, etc. may be used (in the invention of claim 8). Correspondence). In the case of using the spline function, storing the spline coefficient instead of the volume ratio value itself requires less calculation during reproduction. When a cubic spline is used, the volume ratio function is represented by a C2 class function. It should be noted that the spline here is not a so-called spline curve in which a sequence of points representing an outline is displayed as one parameter, but is a two-variable spline interpolation of a volume ratio function F as a function of x and y. Keep it.

In order to obtain the volume ratio distribution on an arbitrary z section, linear interpolation may be performed using the values of the volume ratio function at the upper and lower lattice points. Also, Overh in the z direction
Using auser's piecewise polynomial,

[0044]

[Equation 6]

It is also possible to

Further, in order to smoothly express the outline of the character, the value of the volume ratio function can be subjected to preprocessing by diffusion. For example, for the value of the volume ratio function F _{ij at} the vertex ij, Fnewij is

[0047]

[Equation 7]

It can be obtained as follows. Here, D is a dimensionless diffusion coefficient, which is usually 0.25 or less in consideration of the stability of the explicit diffusion scheme. Formula 7
Equation 7 can be used an appropriate number of times, with F _newij obtained in _{step 1} as F _ij . In order to prevent the character shape from being lost due to excessive diffusion, it is better to set d to 1 or less. Here, d is a distance that is a standard for diffusion, and using the diffusion coefficient D and the number of times of diffusion processing n,

[0049]

[Expression 8] d = 2 · (D · n) ^1/2 Such diffusion processing is also effective for creating a typeface by the method of the present invention based on a character typeface for a dot matrix printer. This is because the jaggedness peculiar to the typeface for the dot matrix printer is smoothed by the diffusion process. As the diffusion scheme, a differential expression other than Equation 7, for example, an implicit scheme

[0050]

[Equation 9]

Etc. can also be used. In this case, F
You need to solve the matrix equation for _new .

In Equations 7 and 9, only diffusion in the xy plane is considered, but diffusion in the z direction may be included. In that case, the diffusion coefficient in the z direction is not necessarily x.
It need not be the same as the diffusion coefficient in the y-plane.

<Third Embodiment> In the above-described embodiment, the corners of the stroke end of a character are chipped off, but this can be prevented by finely dividing the elements at the stroke end. You can FIG. 9 shows the element division of the lowermost part of the vertical bar made fine (corresponding to the invention of claim 5). Which element is subdivided is stored separately. The elements can be subdivided as needed. Also, in order to avoid an excessive increase in storage capacity due to subdivision, the number of bits expressing the volume ratio function F in the subdivided area may be reduced. For example, if F is represented by 8 bits for each element in FIG. 9, F may be represented by 4 bits in the subdivided region.

<Fourth Embodiment> In order to obtain the outline of the stroke of a character, points at which the volume ratio is 0.5 on the sides of the element may be obtained and connected to each other (corresponding to the invention of claim 9). ). When connecting, use a straight line, a spline curve, or the like. Further, when it is desired to make the end point sharp, the contour of the surrounding element can be extrapolated (corresponding to the invention of claim 10) as shown by the dotted line in FIG. 10 to find the character contour in the element. It is separately stored which elements include the ends and which contours to extrapolate from inside.

<Fifth Embodiment> When one character is represented by a plurality of volume ratio matrices, a character having a fine stroke can be handled. FIG. 11 shows a method of expressing a line thinner than the element size as a difference between two volume ratio matrices.

<Sixth Embodiment> As a method for expressing a solid, in addition to the method of using the volume ratio function as in the first to fifth embodiments, the position of the solid surface may be stored. Good (corresponding to the invention of claim 11). For that purpose, a curved surface may be expressed by a piecewise polynomial by using a point for controlling the three-dimensional shape or a feature point on the three-dimensional surface (corresponding to the invention of claim 12). For example, spline surface, Bezi
er curved surface, Overhauser curved surface and the like, a method used in CAD and computer graphics can be used (corresponding to the invention of claim 12).

<Seventh Embodiment> FIG. 12 shows various three-dimensional fonts of the letter I and intermediate fonts thereof. The shape a in FIG. 12 is obtained by adding a portion representing the italicized form of the character I to the solid body in FIG. The shape b in FIG. 12 is obtained by adding a portion representing the bold typeface of the character I to the solid body in FIG. The shape c of FIG. 12 is obtained by adding a portion representing a font having a short vertical length of the character I to the solid body of FIG. The shape d in FIG. 12 expresses a typeface similar to the shape b, but the way of changing the typeface is non-linear (curved), and is different from the shape b. In this way, three or more types of fonts and their intermediate fonts can be represented by one solid.

Up to now, the solid corresponding to the area to be printed has been considered, but conversely, the solid corresponding to the area not to be printed,
That is, it is also possible to consider a portion excluding the solid represented in FIG. Further, a hollow solid body may be considered, and characters may be expressed by the cavity portion.

The cut surface does not necessarily have to be horizontal. By tilting to the front or back or left and right to cut, it is possible to reproduce a character whose typeface changes vertically or horizontally. Furthermore, the cut surface may be a curved surface.

<Eighth Embodiment> In this embodiment, the solid is not cut along planes parallel to each other, but cut along a plane including the z axis. FIG. 13 shows a solid representing the letter I in various typefaces in the case of this method.

(Others) Which plane is used to cut the three-dimensional shape is the type of the typeface and the position of the cut surface, that is, the character font R.
The relationship with the address of the data read from the OM3 is predetermined. Based on this correspondence, the control unit 1 reads the data from the character font ROM 3 to obtain the plane data of the three-dimensional cut surface, that is, the character shape data.

[0062]

As described above, according to the present invention,
Since the character shapes of a plurality of typefaces are stored in the form of a three-dimensional shape, it is possible to store and reproduce a plurality of character typefaces and intermediate typefaces with a small storage capacity and a simple operation.

[Brief description of drawings]

FIG. 1 is the letter I in various typefaces in the first embodiment.
It is a figure which shows the memory | storage method of the shape of.

FIG. 2 is the character I in a specific typeface in the first embodiment.
It is a figure which shows the volume ratio distribution of.

FIG. 3 is a diagram in which the shape of the character I is reproduced using the method of the first embodiment.

FIG. 4 is a block diagram of a dot matrix type printer using the method of the first embodiment.

FIG. 5 is a letter I in a specific typeface in the second embodiment.
It is a figure which shows the volume ratio distribution of.

FIG. 6 is a diagram in which the shape of the character I is reproduced by linear interpolation in the second embodiment.

FIG. 7 is a diagram for explaining a volume ratio interpolation method in the second embodiment.

FIG. 8 shows the shape of the letter I as an Overhauser in the second embodiment.
It is a figure reproduced | regenerated using the piecewise cubic polynomial of.

FIG. 9 is a diagram showing a method of subdividing a character stroke end portion and storing it in a third embodiment.

FIG. 10 is a diagram showing a method of reproducing a character outline in the fourth embodiment.

FIG. 11 is a diagram showing a method of expressing a thin line in the fifth embodiment.

FIG. 12 is a diagram showing a solid representing a character I in the seventh embodiment.

FIG. 13 is a diagram showing a solid representing a character I in the eighth embodiment.

[Explanation of symbols]

 1 control unit 2 external interface 3 character font ROM 4 RAM for external character registration 5 linear interpolation calculator 6 print head

Claims (13)

[Claims] 1. A shape of a solid is stored in a memory so that each cross section when the solid is cut into a plurality of planes represents a character shape of a different typeface, and the solid is desired when a character occurs. A character generation method characterized in that a character shape is obtained by performing image processing for cutting with a cutting surface corresponding to the typeface. 2. The character generation method according to claim 1, wherein a plurality of typefaces are expressed by cutting the solid body in planes parallel to each other. 3. A plurality of typefaces are stored as a solid in which the character shape on the cut surface also changes continuously when the way of cutting the solid is continuously changed. Character generation method described. 4. The space containing the solid is divided into a plurality of elements by a lattice, and the shape of the solid is stored in the form of a volume ratio indicating the ratio of the volume occupied by the solid to the element volume in each element. The character generation method according to claim 1. 5. The character generation method according to claim 4, wherein a part of the element division grid is subdivided. 6. The character generating method according to claim 4, wherein the value of the volume ratio is given and stored in the center, on the surface, on the side, on the grid point or a combination thereof, of the element. 7. The character generating method according to claim 4, wherein diffusion processing is performed on the value of the volume ratio before obtaining the distribution of the volume ratio. 8. The volume ratio is interpolated by any one of linear interpolation, class C3 cubic interpolation, Lagrange interpolation, and spline interpolation, and the solid is represented by the interpolation. Character generation method. 9. A position on a side of an element where a value of the volume ratio takes a predetermined value is obtained, the contour of the solid is obtained by connecting the places, and the volume ratio has a predetermined value based on the contour. The character generation method according to claim 4, wherein the character shape portion described above is printed. 10. The character generating method according to claim 4, wherein a character contour is obtained by extrapolating a character contour in an adjacent element in an element including an end portion of a character stroke. 11. The character generating method according to claim 1, wherein the shape of the surface of the solid is stored as the shape of the solid. 12. The character generating method according to claim 11, wherein the surface shape of the solid is represented by a curved surface by a piecewise polynomial. 13. A storage means for storing the shape of the solid so that each cross-section when the solid is cut into a plurality of planes represents a character shape of a different typeface, and the solid is desired when the character is generated. A character generation device, comprising: an image processing unit that obtains a character shape by performing image processing for cutting with a cut surface corresponding to a typeface.