KR890003318B1 - Apparatus for processing character or pictorial image data - Google Patents

Abstract

The outline of a character which is developed on X and Y coordinates is split into a number of blocks (P1, Pn) (where P1 and Pn are a start point and an end point of an arbitrary block respectively) each defined by a univalent function involving X as a variable. Block data are produced to specify the shape of each block, of which data is stored as the compressed data of one character to accomplish compression of the data. A memory is provided for storing the start point coordinates of a straight portion, and the start point coordinates of each sampling segment established on a curved portion, and the coefficient and the degree of the cubic polynomial which approximates each segment.

Description

Character image data processing system

1 and 2 illustrate a conventional outline method.

3 is a flowchart showing an outline of a processing procedure of the system of the present invention.

4 is a view showing an outline of the configuration in which the present invention system is implemented.

5 is a view showing an example of a character outline.

FIG. 6 is a diagram showing an example in which the outline of the character shown in FIG. 5 is divided into a plurality of blocks. FIG.

7 is a diagram for explaining straight line approximation.

8 is a block diagram showing an embodiment of a configuration for realizing identification of straight portions and curved portions.

FIG. 9 is a view showing details of main parts of the process in the configuration of FIG. 8; FIG.

10 is a view showing a result of identifying a straight portion and a curved portion.

11 (a) to 11 (c) are diagrams for explaining a method of calculating the inclination at each contour point.

12 is a diagram illustrating a process of setting a sample section.

FIG. 13 (a) and FIG. 13 (b) show a situation in which sample points are set.

FIG. 15 shows an example of a format for storing arbitrary one block data. FIG.

Fig. 16 is a diagram explaining a storage method of block data.

FIG. 17 is a block diagram showing an embodiment of a configuration for restoring block data. FIG.

18 is a timing chart showing the operation of FIG.

* Explanation of symbols for main parts of the drawings

1, 50, 90: outline of characters 60: connection point storage unit

61: straight part identification vector length setting part 62: curve dividing point identification angle setting part

63: difference connection point coordinate register 64: current connection point coordinate register

65: all connection point coordinate register 66: vector length calculation unit

67: angle calculation unit between the vectors 68: vector length comparison unit

69: angle comparison unit 70: straight line storage unit

71: curve sub memory 91: approximation curve of the n-th order polynomial

120: compressed data storage section 121: selector

1, 122: magnification memory unit 123: decoder group

124: selector 125: 1-character memory

126: output device

The present invention relates to a character image data processing system which compresses the amount of stored data by storing the outline shape of a character or image (hereinafter referred to as a character). Specifically, the outline of a character is classified into a straight portion and a curved portion. The present invention relates to a character image data processing system in which sample point candidates provided on this curved portion are moved by trial and error to decipher the compressed data and reproduce a character image. The determination of whether or not this trial and error is carried out and in which direction the sample point candidate is to be started is determined depending on the amount of oil ε obtained for each contour point in the sample candidate section. Then, the sample sections are sequentially set at the point of view of the curve section, the curve section is divided into a plurality of sample sections, and the straight section and each sample section obtained here are stored.

It is well known that two-value data obtained by dot decomposition of characters is extremely redundant. Thus, various data compression schemes have been proposed in order to alleviate this redundancy.

Another one is a data compression method called so-called contour method, in which the shape of a character is identified as an outline and the data amount is specified by storing the data specifying the outline.

As the compression method by this contour method, the linear (vector) approximation method like FIG. 1 and the n-th order curve approximation method like FIG. 2 are already proposed.

The linear approximation method illustrated in FIG. 1 is a method disclosed in JP-A-54-149522, JP-A-65-79154, and the like. The outline is approximated by a set of vectors (2) showing the outline (1) of any character shown by a dotted line in a solid line and specifying each vector (viewpoint position, length and inclination, or horizontal and vertical components). By using as encoded data, data compression is enabled.

In addition, the n-th order curve approximation method illustrated in FIG. 2 is a method known from JP Patent Application No. 57-39963 of the present applicant. The outline is an n-th order curve (3) that attempts to compress the data amount by storing the coordinates of the point P group appropriately set on the outline of an arbitrary character as described later, and forms arbitrary (n + 1) points. Is to approximate the desired outline. 2 also illustrates the case of n = 2.

The data compression method by the outline method is characterized by reproducing the compressed data and reproducing the character image by carrying out the storage process, the extraction process or the vector magnification conversion process to reproduce the character image at various magnifications.

However, these conventional methods are, for example, the inclination angle of the left and right tangent lines centering on the connection point Pc of each n-th order curve 3 in FIG. As apparent from the fact that δ becomes discontinuous in any case, there was an inherent defect that the smoothness of the contour (continuity of the inclination of the contour) is not guaranteed.

In general, the outline of a letter has both a straight line and a curved line, and the outline itself is not only continuous but also except for the unusual points such as the intersection of the letter image or the tip of the 'beep'. It has the characteristic that the first derivative (the slope of the contour) changes continuously.

Therefore, the conventional data compression method has a problem that it is difficult to obtain specific compressed data faithfully to outlines, and it is not possible to accurately remove the unnaturalness (slope discontinuity) of characters reproduced on the basis of the data.

In order to solve such a problem, the method of the present applicant JP-A-58-134745 has already been proposed.

The data compression method disclosed herein is also a kind of contouring method, and has the following problems. That is, since (1) all the sample intervals in any one block are approximated at once, it is easy to generate a deviation from the contour at the connection point at the portion where the linear portion and the curved portion are connected, and the portion to be reproduced as a straight line is also Since the approximation is affected by the approximate curve of the front and rear sample sections, the reproducibility of the straight line is inferior.

(2) In order to avoid this, it is evident that a large number of sample points must be set, divided into many polynomials, and approximated, thereby increasing the amount of data.

(3) Also, since each sample section in any one block was approximated at once, it became apparent that the sample point would be affected by this and the approximate curve of other sample sections would also change.

(4) In addition, each time a sample point is established, an approximation curve has to be recalculated for all sample intervals on any one block, and furthermore, a complicated operation is required for encoding.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data processing system by an improved contour method, and another object of the present invention is to obtain a compressed character that obtains compressed data that faithfully reproduces an outline while reducing computation time in obtaining compressed data. It is another object of the present invention to provide a character image data processing system that can store compressed data that faithfully reproduces the smoothness of outlines, and can obtain a sufficiently high data compression ratio.

An outline of the processing level of the system of the present invention will be described according to the flowchart shown in FIG.

The input character image is dot-separated into x and y matrices (30), and the outline of this dot-decomposed character is extracted (31). The extracted contour is approximated linearly with a vector whose deviation from the contour is less than or equal to the tolerance (32). The linearly approximated contour is identified as a straight line and a curved line according to the vector length (33). If necessary, the curved portion and the identified contour are divided based on the intersection angle of adjacent vectors (34). In preparation for curve approximation of the contour of the curved portion in the cubic polynomial, the inclination at each contour point forming the contour is obtained (35). The third-order polynomial is obtained from the start point, the end point coordinates, and the slope of the sample candidate section set in the curve approximation section. Then, while extending or shortening the sample code section, the sample section which is the longest within the range where the deviation between the third-order polynomial and the contour approximating this section is accommodated below the tolerance is obtained, and the start point and the end point of the section are sampled. We decide by point. (36)

In this way, when the sample intervals are obtained in order, and a third order polynomial approximating each sample interval is obtained, first order functions of the respective third order polynomials are obtained, and the slope of each contour is calculated again (37). The sample points are determined as described above according to the newly obtained slopes and coordinates of each contour point, and a third order polynomial faithful to the contour is calculated (38). The view coordinates of the linear sample section obtained as described above and the view coordinates of the respective curve sample sections constituting the curved portion and the coefficients and orders of the cubic polynomial (39) are then coded (39). Remember (40).

The compressed data of the stored character outline is distributed and decoded by a plurality of decoders (41), and the desired character outline is restored (42) according to the decoding result.

Next, the outline of the structure which implemented the system of this invention is demonstrated according to FIG.

Reference numeral 41 denotes an outline point storage means for storing the position of the outline point Qj of the character image, and 42 denotes a start point Pi and an end point Pi + of an arbitrary outline point Qj among a plurality of outline points Qj constituting the character image contour. By calculating the deviation of the length of the vector and the contour point of the vector with respect to the vector Vi as 1, the vector calculation means for finding a vector Vi whose maximum length li is the maximum when the deviation amount is equal to or less than a predetermined allowable value. (43) is a first comparison means for comparing the length li of the vector Vi with a preset length 1, (44) is the intersection angle θi between the vector Vi and the vector Vi-1 adjacent to the vector Vi and And second comparing means for comparing the preset angle θ.

k일때, 상기 윤곽구간[Pi, Pi+1]을 곡선부로 식별하고, 다음의 벡터에 대해서도 반복하여 상기 비교를 행하고 벡터 Vi + k 에서 li + k > L 가 될때 또는 θi + k < θ 가 될때 , 그때까지의 윤곽구간[Pi, Pi+k]을 하나의 연속한 곡선부로 식별하는 식별수단, (46)은 상기 곡선부의 윤곽구간[Pi, Pi+k]에 대하여 윤곽의 시점 Qj를 제1의 샘플점으로 하고 임의의 윤곽점 Qj +r 을 샘플점 후보로 하는 샘플후보구간[Qj , Qj+r]을 설정하고 이 샘플점 Qj와 샘플점 후보Qj+r의 좌표(xj, yj),(xj+r, yj+r)및 그 경사 tj, tj+r에 의거하여 상기 샘플 후보 구간[Qj,Qj+r]을 3차 다항식 f(x)으로 곡선 근사하는 곡선 근사수단, (47)은 이 3차 다항식 f(x)과 상기 샘플 후보 구간의 각 윤과점과의 편위량 ε산출수단.(45) identifies the contour section [Pi, Pi + 1] approximating the vector Vi as a straight line when the comparison result is li> L, and the comparison result is li

When k, the contour section [Pi, Pi + 1] is identified as a curved portion, and the comparison is repeated for the next vector and when li + k> L in the vector Vi + k or θ i + k <θ. Identification means for identifying the contour section [Pi, Pi + k] up to that point as one continuous curved portion, and (46) firstly designating the starting point Qj of the contour with respect to the contour section [Pi, Pi + k] of the curved portion; Set the sample candidate section [Qj, Qj + r], which is a sample point of, and the arbitrary contour point Qj + r is a sample point candidate, and coordinates (xj, yj) of this sample point Qj and sample point candidate Qj + r, curve approximation means for curve approximating the sample candidate interval [Qj, Qj + r] with a cubic polynomial f (x) based on (xj + r, yj + r) and its slopes tj, tj + r, (47) Means for calculating the amount of deviation? Between the third polynomial f (x) and each lattice point of the sample candidate section.

(48) is the third comparison means for comparing the obtained deviation amount ε and the tolerance △, and (49) sets the current sample point candidate as the next sample point according to the comparison result, Sample interval setting means for sequentially setting the sample interval over the one continuous curved portion and all the identified contour intervals [Pi, Pi + k] with the sample point as the starting point of the next sample candidate interval.

Reference numeral 50 denotes storage means for storing the view coordinates of the linear section and the view coordinates of each sample section set in the curve section, and the coefficients and orders of the third order polynomial approximating each sample section.

Next, data processing is described in detail in each section.

[Image input 30]

By raster scanning of a scanner device or the like, the characters are dot-decomposed onto the x and y matrices, and the bit pattern data obtained therefrom becomes character data to be processed.

[Contour Extraction (31)]

The dot position (contour point Q) in which two-value data corresponding to the decomposed character data changes from "0" to "1" or "1" to "0" in the x or y direction is obtained. The position of the point is stored in the outline point storage means 41.

FIG. 5 is a diagram showing one example of the character outline obtained in this way, and one character pronounced as "な" (b) is illustrated.

However, when the character image is reproduced by the raster scanning method, the raster image is drawn between the start point and the end point of the scan. Therefore, the information of the contour parallel to the Y axis (register scanning direction) is not necessarily necessary.

FIG. 6 omits the portion of the yaw height and parallel to the Y axis shown in FIG.

In the figure, the "0" table is the starting point and the end point of each outline, and the narrow space sandwiched between these "0" tables is omitted.

As is apparent from the figure, the x coordinate value of each contour is monotonously increasing or decreasing between this starting point and the end point. That is, 1 is a function y whose x is a variable.

Accordingly, the contour of FIG. 6 can be obtained by sequentially obtaining the sections (blocks B1, B2, B3 ....) where the value of the x coordinate monotonously increases or decreases with respect to the contour of FIG.

[Linear approximation (32)]

In the vector calculation means 42 of FIG. 4, the linear approximation is performed by a plurality of vectors Vi which are set so that their length li, which is equal to or less than a predetermined tolerance of the amount of deviation from the contour, is maximized.

For example, in FIG. 7, a straight line approximation is performed on a set of vectors Vi (where i = 1 to n-1) of the outline 51 indicated by a dotted line in any one block [P1, Pn]. Connection point coordinate storage unit (Fig. 8) shows coordinates (xj, yj) of contour point Qj (where j = 1 to m) corresponding to the connection point Pi (i = 1 to n) of Vi of each vector. Remember at 60).

[Identification of straight and curved portions of the contour (33)]

As described above, in general, the outline of a character has both a linear portion and a curved portion, and in Japanese Patent Application Laid-open No. 58-134745 of the present applicant, since the entire outline in one block is about to be approximated at once, In the part where the curved portion connects, many sample points must be set near the connection point and expressed by a large number of approximation equations, and the amount of data in this part increases, indicating a decrease in the compression ratio.

Therefore, the present invention first identifies whether the shape of the contour section approximated by the vector according to the length li of the vector determined by the linear approximation is a straight portion or a curved portion, and separately processes the straight portion and the curved portion separately. In order to solve the problem, even a character having a complicated contour shape can obtain an excellent reproduction image.

FIG. 8 is a block diagram showing one embodiment of the configuration in which the straight portions and the curved portions of the contour are realized, and FIG. 9 is a diagram showing details of main parts of the process in the configuration of FIG.

8 and 9 correspond to the vector calculation means 42, the comparison means 43, 44, and the identification means 45 in FIG.

In Fig. 8, reference numeral 60 denotes a connection point storage unit for storing connection points obtained by the linear approximation 32 in units of blocks, and reference numeral 61 denotes a linear part identification vector length setting for presetting a vector length L for identifying. (62) is a curve dividing point identification length setting unit which sets in advance an angle θ for identifying a point for dividing the curve, and (63) is the coordinate of the i + 1th connection point Pi + 1, that is, the connection point Pi + 1. The next connection point coordinate register for retaining the coordinates (xj + S, yj + S) of the corresponding contour point Qj + S, where 64 is the coordinate (xj, yj of the contour point Qj corresponding to the i-th connection point P. The current connection point coordinate register for holding (), (65) is the previous connection point coordinate register for holding the coordinates (Xj-u, yj-u) of the contour point Qj-u corresponding to the i-1st connection point Pi-1. (66) denotes respective coordinates of the next connection point coordinate register 63, the current connection point coordinate register 64, and the previous connection point coordinate register 65; The inter-vector angle calculation unit (68) for calculating the inter-vector angle θ i at the connection point Pi at, is calculated by the vector length L set by the straight line identification vector length setting unit 61 and the vector length calculation unit 66. A vector length comparator, 69 for comparing vector lengths li, compares the angle θ set by the curve dividing point identification angle setting unit 62 with the angle θ i between vectors calculated by the angle calculation unit 67 between the vectors. The angle comparing unit 70 denotes a linear storage unit for storing sections of the linear unit according to the comparison result of the vector length comparing unit 68. Reference numeral 71 denotes a curve storage unit for storing the section of the curve in accordance with the comparison result of the vector length comparison unit 68 or the comparison result of the vector length comparison unit 68 and the angle comparison unit 69. .

Next, the operation will be described. First, the angle θ is set in the point identification angle setting part 62 to curve the vector length L in the linear part identification vector length setting part 61. Next, the connection point coordinate storage unit 60 sends the coordinates of the starting point P1 of the arbitrary blocks [P1, Pn] to the next connection point coordinate register 63. At this point in time, since nothing is stored in the current connection point coordinate register 64, the vector length calculation unit 66, which will be described later, cannot obtain the vector length.

The connection point coordinates stored in the next connection point coordinate register 63 are transferred to the current connection point coordinate register 64, and the coordinates of the next connection point P2 are newly stored in the next acceleration point coordinate register 63. Subsequently, the coordinates of the connection point stored in the current connection point coordinate register 63 are shifted to the current connection point coordinate register 64, respectively, and the coordinates of the next connection point are stored in the connection point coordinate storage unit 60 in the next connection point coordinate register 63. do.

를 산출한다. 산출한 길이 li는 벡터 길이 비교부(68)에서 상기 직선부 식별 벡터길이 설정부(610에서 미리 설정한 벡터 길이 L 와 비교한다.The vector length calculation unit 66 is the coordinate (xj + S, yj + S) of the i + 1th connection point Pi + 1 of the next connection point coordinate register 63 and the i-th connection point of the current connection point coordinate register 64. Vector Vi and length at the coordinates of Pi (xj, yi)

To calculate. The calculated length li is compared with the vector length L previously set in the linear identification vector length setting unit 610 by the vector length comparison unit 68.

In the case of li> L, the contour section [Pi + Pi + 1] approximating to the vector Vi is identified by a straight line, and the start point and end point coordinates of the section are information about one straight line. Remember).

L인 때는 윤곽구간[Pi+Pi+1]을 곡선부로 식별하고, 이 구간[Pi+Pi+1]의 시점 좌표 및 종점 좌표를 곡선부에 관한 정보로서, 곡선부기억부(71)에 기억한후, 다음의 구간[Pi+1Pi+2]도 곡선부이면 그때까지 곡선부로 식별해온 구간[Pi+Pi+2]을 연속한 하나의 곡선부로하고, 그 시점 좌표와 종점 좌표를 하나의 곡선부에 관한 정보로서 곡선 부기억부(71)에 기억한다.Again, li

In the case of L, the contour section [Pi + Pi + 1] is identified by the curved portion, and the start coordinates and the end point coordinates of the section [Pi + Pi + 1] are stored in the curved portion storage portion 71 as information about the curved portion. After that, if the next section [Pi + 1Pi + 2] is also a curved section, the section [Pi + Pi + 2], which has been identified as a curved section until then, is one continuous curved section, and the starting point and end point coordinates are one curved line. The information stored in the curve is stored in the curve storage unit 71.

Then, the above comparison is repeated until it is identified as the straight portion of the next contour section and when li + k> L in the vector Vi + k, the contour up to that point already stored in the curve storage unit 71 is obtained. The start point coordinates and the end point coordinates corresponding to the section [Pi + Pi + k] are fixed as information on one curved portion.

As described above, when information on one straight portion or information on one curved portion is obtained, the same identification is repeated for the next vector and constitutes one arbitrary block [Pi, Pi]. Data of the straight and curved portions is stored in the storage portions 70 and 71, respectively. The mode block constituting one character is identified below.

[Segmentation of the outline (34)

On the other hand, in the vector-to-vector angle calculation unit 67, the coordinates (Xj) of the connection points Pi-1, Pi, and Pi + 1 in the difference connection point coordinate register 63, the current connection point coordinate register 64, and the previous connection point coordinate register 65, respectively. -u, yj-u) and (xj + S, yj + S) are read out, and the angle between the vectors (crossing angle between the vector Vi and the vector Vi-1 adjacent to each other) θi shown in FIG. 7 is calculated. The calculated angle between the vectors θ i is compared with the angle θ set in the curve splitting point identification angle setting unit 62 in the angle comparison unit 69. And when θ i <θ, the curve division signal is supplied from the angle comparison section 69 to the curve storage unit 71.

In the practice of the present invention, the curve division signal 71 is operated in advance or whether the curve division signal is ignored in accordance with this curve division signal. When the command to ignore the curve division signal is instructed, the curve sub storage unit 71 faithfully executes the operation described in the section (identification 33 of the straight line portion and the curve portion of the outline).

In other cases, i.e., when the curve portion is continuously identified in the vector Vi, for example, in the state instructing the operation of the curved portion storage portion 71 according to the curve division signal, and becomes θ i +1 <θ in the vector Vi + k. This curve division signal is supplied to the curve storage unit 71. The curve storage unit 71 identifies the connection point Pi + k as a curve dividing point newly and coordinates the viewpoint corresponding to the contour section [Pi, Pi + k] up to that point already stored in the curve storage unit 71. And end point coordinates are fixed as information about one curved portion.

By the way, unusual points, such as the intersection part of the molecular image and the tip of the &quot; beep &quot;, are often identified as this curve dividing point. In Japanese Patent Application Laid-Open No. 58-134745, many connection points exist in the vicinity of this unusual point, and it takes time to process the approximation curve obtained, but the contour is divided at the curve division point obtained above, and each curve approximation before and after As a result, the processing time is fast, and an approximate curve can be easily obtained thereon.

FIG. 10 shows an example in which the processes from [linear approximation 32] to [division 34 of outlines] were performed on the outline shown in FIG.

In the drawing, o is a starting point and end point of one block, o is a connection point obtained by [straight approximation and identification of a curved portion 33], and o is a curve dividing point.

In addition, the two curve dividing points shown are set because the crossing angle θn is smaller than the predetermined identification angle θ.

[Calculation of Slope of Each Contour Point 35]

When approximating the outline shape of the above-mentioned curved part using a cubic polynomial, this cubic polynomial is uniquely determined when the coordinate value and the inclination of two points are determined. Therefore, first, a method for obtaining the inclination at each contour point on the contour will be described.

In the embodiment of the present description, the inclination of each contour point is obtained by extracting only a predetermined number of contour points before and after the contour point, and calculating the inclination of the contour point and the slope of the line segment connecting the extracted contour points, respectively. The inclination at the contour point was calculated in advance and stored.

Next, the calculation method of the inclination at each contour point is demonstrated according to the example of the curve part shown in FIG.

First, the case where the inclination t1 at the contour point Q1 (the start point of the curved portion) in FIG. 11 (a) is obtained will be explained. Only an arbitrary number of contour points existing behind the contour point Q1 are extracted to be different from the contour point Q1. The inclination of the line segments connecting the contour points is calculated, and the inclination t1 at the contour point Q1 is calculated from the inclination of each of these line segments in a manner described later.

의 경사 m12, 선분

의 경사 m13을 구한다.For example, in the case where the contour point is extracted by extracting two contour points on the rear side of the contour point Q1 for which the slope is to be obtained, first, the segment

Slope of m12, segment

Find the slope of m13.

The slope m12 of the line segment is at two coordinates (x1, y1), (x2, y2)

You can get it by The same applies to the case of the slope m13.

When the slopes m12 and m13 of the line segments are obtained, the slope t1 at the contour point Q1 is

Obtain by

Next, the case where the inclination t2 at the next contour point Q2 is calculated | required according to FIG. 11 (b) is demonstrated.

In this case, only a predetermined number of contour points existing before and after contour point Q2 are extracted, and the inclinations of the line segments connecting the contour points at the height of contour point Q2 are obtained, respectively, to be the inclination t2 at contour point Q2.

For example, when the contour point is extracted two points front and back to obtain the inclination, only one point of Q1 can be extracted from the front side at the contour point Q. In this case, the slope t2 is obtained by the following equation by extracting one point front and back.

If the specified number of contour points does not exist as described above, the slope is obtained by extracting the maximum number of contour points within the specified range.

Next, the case where the inclination t3 at contour point Q3 is calculated | required like FIG. 11 (c) is demonstrated. In this case, in the contour point Q3, the predetermined number of contour points exist before and after. Therefore, the slopes m13, m23, m34, and m35 of each line segment connecting the contour point Q3 and the other contour points are calculated to calculate the slope t3 at the contour point Q3,

Obtain from

Then, in the same manner, the inclination at each contour point is calculated, and the inclinations tn and tn-1 at the end point Qn of the curved portion or the contour point Qn-1 adjacent thereto are shown in Figs. 11 (a) and 11 ( b) It calculates like the case where the inclination of the viewpoint Q1 shown in the figure, or the contour point Q2 adjacent to it is calculated | required.

In this way, the calculation of the inclination at each contour point is performed by extracting only a predetermined number of contour points related to the front and rear of the contour point. The above description is an example when the predetermined number = 2.

[Determination of Sample Point (36)]

When the inclination at each contour point which comprises a curved part is calculated | required as mentioned above, a sample section is set on the outline corresponding to a curved part next.

The sample section is set by the curve approximation means 46, the deviation amount calculating means 47, the comparing means 48, and the sample section setting means 49 in FIG.

12 is a view showing the process. So, first, two contour points Qj and Qj + r are selected in sequence according to the procedure described later in order to set the sample interval (see Fig. 13).

In the following description, among these two contour points, the front contour point Qj is called a sample point, and the rear contour point Qj + r is called a sample point candidate. The section using these two points as the starting point and the ending point is called a sample candidate section [Qj, Qj + r]. The sample point Qj is set at the beginning of the curve portion as an initial condition, and the sample point candidate Qj + r is set at a position separated by r contour points from the sample point Qj.

So, first, based on the coordinates (xj, yj), (xj + r, yj + r) of these sample points Qj and sample point candidates Qj + r, and their slopes tj and tj + r, they pass through these two points. The coefficients and dimensions of the third-order polynomial f (x) are obtained, and each deviation amount ε between all contour points existing in the sample candidate intervals [Qj, Qj + r] and the approximation curve obtained by the third-order polynomial is predetermined. The validity of the obtained approximation curve is determined by comparing whether or not the tolerance is less than or equal to.

의 경우, 상기 구해진 근사곡선을 허용할 수 있는 것으로 판단한다. 그런데, 하나의 근사곡선에 의해 표현할 수 있는 구간이 길수록, 바꾸어 말하면 주어진 임의의 윤곽을 표현하는데 필요한 근사곡선의 수가 적을수록 데이타의 수가 적어져서 효율좋게 압축할 수 있다.Now, for all contour points of the sample candidate section [Qj, Qj + r], ε

In this case, it is determined that the obtained approximation curve can be tolerated. However, the longer the interval that can be expressed by one approximation curve, in other words, the smaller the number of approximation curves required to express a given arbitrary contour, the smaller the number of data and the more efficient the compression can be.

△일때, 현재의 샘플점후보 Qj+r에 인접하는 윤곽점Qj+r+1을 새로운 샘플점후보로하여 상기 비교를 하고, 이후 비교 결과가 하나라도 ε>

로 되기까지 샘플점후보를 순차 갱신하여 상기 비교를 반복하고, 윤곽점Qj+r+p에서 하나라도 ε>

로 되었을때, 그 직전의 윤곽점 Qj+r+p-1을 제2의 샘플점으로 하여 샘플구간[Qj, Qj+ r+p-1]을 설정하고, 이 샘플구간[Qj, Qj+r+p-1]에 있어서의 근사곡선이 주어진 임의의 윤곽을 표현하는데 필요한 근사곡선의 하나로서 결정된다.Thus, for the sample candidate sections [Qj, Qj + r], which are determined to be the sample point candidates of the arbitrary contour point Qj + r set for the first time, the approximation curves obtained as described above, and the sample candidate sections [Qj, Qj +]. r] is calculated from each contour point of r], and is compared with the tolerance △.

When Δ, the comparison is made using the contour point Qj + r + 1 adjacent to the current sample point candidate Qj + r as a new sample point candidate, after which any comparison result is ε>

The above comparison is repeated by sequentially updating the sample point candidates until it becomes, and at least one of the contour points Qj + r + p is ε>

Is set, the sample section [Qj, Qj + r + p-1] is set using the immediately preceding contour point Qj + r + p-1 as the second sample point, and this sample section [Qj, Qj + r + The approximation curve in p-1] is determined as one of the approximation curves required to express a given contour.

와 비교한 결과가 하나라고 ε>

일때, 현재의 샘플점후보 Qj+r에 인접하는 윤곽점 Qj+r - 1을 새로운 샘플점 후보로서 상기 비교를 하고, 이후 비교결과가 모두 ε

되기까지 샘플점후보를 순차갱신하여 상기 비교를 반복하여, 윤곽점 Qj+r-p에서 모두ε

로 되었을때, 이 샘플점후보 Qj+r-p를 제2의 샘플점으로 하여 샘플구간[Qj, Qj+r-p]을 설정하고, 이 샘플구간[[Qj, Qj+r-p]에 있어서의 근사곡선이, 주어진 임의의 윤곽을 표현하는데 필요한 근사곡선의 하나로서 결정된다.On the other hand, the approximation curves obtained as described above with respect to the sample candidate sections [Qj, Qj + r], which are determined to be the sample point candidates, which are initially set to arbitrary contour points Qj + r, and the sample candidate sections [Qj, Qj]. calculate deviation ε with each contour point of + r]

Compared with ε>

, The contour point Qj + r−1 adjacent to the current sample point candidate Qj + r is compared as a new sample point candidate, and then the comparison results are all ε

The sample point candidates are sequentially updated until the comparison is repeated, and at the contour point Qj + rp, ε

When the sample point candidate Qj + rp is set as the second sample point, the sample interval [Qj, Qj + rp] is set, and the approximation curve in this sample interval [[Qj, Qj + rp] is It is determined as one of the approximation curves needed to represent a given contour.

의 범위내에서, 최장으로 되는 샘플구간을 결정하면서, 윤곽을 샘플구간에서 분할해간다. 그리고, 이 샘플구간에 의해 결정하는 3차 다항식으로 윤곽이 근사해진다.By such a process, the deviation amount epsilon

The contour is divided in the sample interval while determining the longest sample interval within the range of. The outline is approximated by a cubic polynomial determined by this sample interval.

Next, the calculation of the approximation curve and the calculation method of the amount of deviation are explained based on FIG. In Fig. 13 (a), reference numeral 90 denotes a contour, B denotes a contour point on the contour 90, 91 denotes an approximation curve of the cubic polynomial f (x), and 92 denotes a sample candidate interval [Qj, Qj + r] is a straight line connecting two points between the starting point Qj and the end point Qj + r, (93) is the vertical line lowered from the point B to the straight line 92, C is the intersection of the approximation curve 91 and the vertical line (93), BA is the amount of deflection εx in the x direction between the contour 90 and the approximation curve 91 at point B, and BC is the amount of deflection εy in the y direction between the contour 90 and the approximation curve 91. to be.

The slopes tj, tj + r, coordinate values (xj, yj), and (xj + r, yj + r) of the calculated time point Qj and sample point candidate Qj + r are substituted into the following three equations.

When the approximation curve is obtained as described above, the amount of deviation ε between the approximation curve and each contour point is obtained, respectively.

FIG. 13 (b) enlarges the amount of deflection epsilon between the outline 90 and the approximation curve 91 in the thirteenth (a). In the figure, it is assumed that the line segment Ca is parallel to the straight line 92, and the inclination of the straight line 92 is the inclination m of the line segment CA. And, as shown, in the case of m 1>, when the deviation amount εx in the X direction between the point B and the approximation curve 91 is obtained, the desired deviation amount ε is

Can be obtained as

1일 때는 마찬가지로And although not shown in the drawings

When it is 1

The desired amount of deviation ε can be obtained from.

In the above description, if the amount of deviation ε in the following sample candidate section [Qj, Qj + r + p] exceeds the tolerance, the sample candidate Qj and Qj + p-1 in advance is taken as the sample point. The interval was determined.

However, in another embodiment, when the tolerance is exceeded, the sample point candidates Qj and Qj + p are temporarily stored at that time, and the deviation amount ε is evaluated when the sample point candidate section is several points forward. All. When the tolerance condition is satisfied in the sample candidate section up to several points from the sample point candidate, the candidate section is corrected to a new sample section, and the above-described evaluation process is repeatedly executed while advancing the sample point. By performing this read ahead, the sample interval can be made longer and the data compression product is improved. Of course, when the tolerance is reached even before a predetermined number of points, the sample interval is determined using Qj + r + p-1 as the sample point.

[Sloped Reproduction (37) of Each Contour Point]

Since the contour point for obtaining the inclination of each contour point obtained by the [inclination calculation 35 of each contour point] and the predetermined number of contour points before and after the contour point are quantized and obtained from the inclination of each line segment, It may be different from the slope of the outline. Therefore, in order to approximate the outline more faithfully as necessary, the slope is calculated again as follows. That is, the inclination obtained by the first derivative function f '(x) of the cubic polynomial f (x) in each sample section is taken as the inclination at each contour point of this sample section. In the embodiment of the present invention, after each sample section is determined, all slopes at the contour points of each sample section are obtained and stored in advance.

[Recrystallization of Sample Point]

When the inclination at each contour point is calculated again by the [inclination recalculation 37 of each contour point], the said [determination 36 of a sample point] is used using the inclination in each calculated contour point. ], And the sample interval determined again while reducing the sample point can be reduced, thereby improving the data compression rate.

By processing the above [recline recalculation 37 of each contour point] and [recrystallization of the sample point 38], the contour can be approximated more faithfully, and the data compression ratio is also improved. Requires processing time.

Moreover, in the case of a simple character, since the outline of the character is approximated faithfully, the above processing is not necessary.

FIG. 14 shows an example in which the processes from [decision 36 of sample point to recrystallization 38 of sample point] to the outline shown in FIG. 10 were performed.

가 새로 설정된 샘플점이다.As in FIG. 10, ○ denotes a start and end point of one block, ▲ denotes a connection point, ● denotes a curve dividing point, * denotes a linear portion, and a non-marked curve portion.

Is the newly set sample point.

[Encoding 39] and [Storage of Compressed Data 40]

Each linear part stored in the linear storage unit 70 of FIG. 8 is regarded as a sample section, and the viewpoint coordinates are encoded.

Subsequently, the viewpoint coordinates of each sample section in the curve section obtained by the above [Determine 36] or [Re-determine 38] of the sample point, and the angle of the approximation curve represented by the cubic polynomial f (x). Coefficients and orders are coded separately.

By storing these coded data in the storage means 50 of FIG. 4, compressed data faithful to the contour can be obtained.

FIG. 15 is a diagram showing an example of a preferable format of any one block of data to be applied in the practice of the present invention as described above.

In the format of the drawing, the block header stores the coordinates of the end point of one block and the number of sample sections of the straight and curved portions existing in the one block, and the segment header contains the coordinates of the start point of the one sample section and the third order polynomial f. The order of (x) is stored, and the segment information stores the coefficients of the third order polynomial f (x) obtained by the order. The coded data of the sample section constituted by the segment header and the segment information is arranged by the number of sample sections stored in the block header to form block data for specifying the contour of one block.

The data is structured in the same format for the other blocks, and becomes compressed data that specifies the outline shape of one character as a whole.

Next, when storing the block data coded by the above format, the decoding processing time for each block is in the order of the longest block, for example in the case of making the restoration of the contour high speed. A storage method for storing block data in the storage means 50 will be described.

For example, FIG. 16 (a) is a diagram showing each block of the letter "A" (in the description, each block is numbered 1-20). The memory is stored in order from the long time required for decoding (for example, the distance between the start and end points of each block in the X direction is long). In the example of the sixteenth (a), the longest time required to decode one block is the block 12, which is followed by the block 10 and the block 16, and the block 3 is the shortest.

Therefore, the compressed data for one character finally obtained by this example is stored as a set of block data as shown in FIG. 16 (b).

[Distributed Decoder 41]

What has been described so far has been the creation of compressed data specifying contours.

Next, a method of restoring the original outline will be described.

In general, restoration of an outline is performed as follows. First, block data is transmitted to the decoder in block data units. The decoder then restores this block data. When the restoration of one block data is completed, block data that has not been restored is sequentially transmitted to the decoder. In this way, the decoder decompresses the block data for one character to restore the compressed data to the outline.

Next, as shown in FIG. 16 (b), the case of the compressed data stored in the order of the long time required for decoding the block data for one character is explained.

In the following description, an embodiment in which the block data for each block is sequentially transmitted to a plurality of decoders for processing in order to restore the contour, and the next block data is processed by the processed decoder will be described.

Next, a description will be given based on FIG. 17 and FIG. 18. Fig. 17 is a block diagram showing one embodiment for contour restoration in the present invention.

In the figure, reference numeral 120 denotes a compressed data storage unit for storing each block data in the order of long time required for decoding one block, (storing means 50 in FIG. 4), and 121 denotes one block data to be described later. Selectors 1 and 122 for selecting and transmitting a decoder are a magnification storage unit for storing a desired magnification separately input, and 123 is a decoder group consisting of n decoders for restoring the block data to a contour corresponding to the magnification. Selector 2, 125 which selects a decoder which has been processed from the decoder group 123 and transmits the decoded outline data to the one-character memory unit 125 to be described later. The one-character memory unit 126, which stores the contour data sent by the user, is an output device for printing or displaying characters on the basis of the contour data of the one-character unit that has been stored in the one-character memory unit 125.

The following operation is described.

The selector 1 121 is arranged in the order in which the time required for decoding one block in the compressed data storage unit 120 is long (for example, in the order of blocks 12, 10, 16, ..., in FIG. 16). To transmit. The selector 1 121 selects and transmits the transmitted block data in order from the decoder 1 of the decoder group 123.

The decoder which has finished the transmission of the block data starts the reconstruction processing of the contour based on the block data and the desired magnification data stored separately in the magnification storage section 122. The selector 2 124 sequentially selects the decoders for which the restoration process has been completed, and transmits the deconstructed contour data to the one-character memory unit 125. The decoder, which has completed the restoration process for one block, requests the selector 1 121 to transmit block data, and the next block data for one block is transmitted.

FIG. 18 is a timing chart showing an example of the processing status of each decoder group 123 shown in FIG.

In the figure, T1 is a time for transmitting block data to each decoder in the selector 1 121, and T2 is a time for transmitting contour data decoded by each decoder to the one-character memory unit 125 through the selector 2 124. FIG. T3 is the decoding process time of block data in each decoder. T4 represents the processing time for one character.

When the block data of n block portions is transmitted to the decoders 1 to n and processing starts, the next n + 1 block data is transmitted to the decoder having the shortest processing time (in this case, decoder 3) and continues processing. . In addition, since each block data to be transmitted is arranged in order of decreasing processing time as described above, as shown in FIG. 18, each decoder ends processing at the same time, and decoding of one character is completed. .

That is, since each decoder operates evenly and proceeds to decode the block data, the decoder starts decoding the block data of the next character without waiting for another long time until the decoding operation of one decoder is completed. By distributing to the decoder and supplying n blocks of data, the entire decoding time can be shortened.

[Reconstruction of the outline (42)]

As described above, one block of contour data reconstructed by each decoder is used for the contour data of one character stored in the one-memory storage unit 125, for example, a laser beam printer, a CRT photographic magnet or various display devices. Supply to the output device 126, the desired character is restored.

As described above, according to the present invention, the contour is identified by the straight portion and the curved portion, the straight portion is represented by the straight line, and the curved portion is represented by the curve approximation, so that the character image can be faithfully reproduced. In addition, since the curve portion is sequentially divided in the sample section that can be most appropriately curved, the contour can be faithfully reproduced with a small sample score. In addition, the n-th order polynomial that curve-approximates each sample section is calculated for each sample section considering the inclination of the start point and the end point of each sample section, and thus can be processed at high speed without complicated calculation.

In addition, since the outline is approximated by a cubic polynomial, the deterioration of the character image quality at the time of high magnification conversion, which is a drawback of the conventional vector approximation method, can be eliminated.

As a result of applying the character image data processing system according to the present invention described above to the famous Hiragana character "A" composed of 800 x 800 dots, when the tolerance for the image of the desired character is 1 dot, The data compression rate was obtained.

In addition, although the above description is a description in the case of protecting and compressing characters, it is clear that various marks, symbols, pictures, and the like other than the characters can be handled in the same manner.

According to the present invention, it is possible to provide a character image data processing system which can attain high speed data which faithfully stores the smoothness of the contour at a sufficiently high compression ratio.

Claims (1)

In a character image data processing system configured to store code and data for specifying a character image contour, a vector Vi having one of a plurality of contour points Qj constituting the character image contour as the starting point Pi and the end point P + 1. Vector calculating means 42 for obtaining a vector Vi whose deviation amount is equal to or less than a predetermined allowable value and whose length li is maximum by obtaining the length of this vector and the deviation amount of this vector and the contour point; First comparing means 43 for comparing the length li of the vector Vi with a preset length L; Second comparison means (44) for comparing the intersection angle θi between the vector Vi and the vector Vi-l adjacent to the vector Vi and the preset angle θ; When the comparison result is li> L, the contour section [Pi, Pi + 1] approximating to the vector Vi is identified by a straight line, and the comparison result is li

When L, the contour section [Pi, Pi + 1] is identified as a curved portion, and again

When the above vector is repeated, the comparison is repeated. When the vector Vi + k becomes li + k> L, or when θi + k <θ, the contour section [Pi, Pi + k] until one Identification means (45) for identifying a continuous curved portion of the; And a storage means 50 for storing the viewpoint coordinates of the linear section, the viewpoint coordinates of each sample section set in the curve section, and coefficients and orders of the third order polynomial approximating each sample section. Processing system.

Images