Image Processing System

1. Field of the Invention

The present invention relates to a method of transforming delineative patterns such as graphic characters, which method is used with a graphic pattern processing system employing vector data for processing the delineative patterns, and more particularly, to an image processing system in which contour line data, composed of vector data, of the delineative pattern is moved by discriminating the signs of the normal vector component of the contour line data so that the widths along the vertical and horizontal directions of the delineative pattern can be changed independently from each other.

2. Related Background Art

The method of processing graphic characters in the form of vector data is very advantageous in its high data compression rate and its high quality of displayed graphic patterns which have undergone one or more desired graphic pattern transformations, such as magnification, reduction and the like. However, with the conventional pattern transformation, when a character "H", as shown in FIG. 7A, for example, is subjected to proportional magnification, the resultant transformed characters are such as those shown in FIG. 7B and FIG. 7C. Thus, in case where a character is magnified or reduced in scale, the ratio of the width along the vertical direction to the width along the horizontal direction is constant and the relative width between both directions cannot be changed.

FIG. 1 is a block diagram illustrating an embodiment of the image processing system according to the present invention;

FIG. 2 is an example of vector data of the contour of graphic character "P";

FIG. 3 shows normal vectors of the vector data of FIG. 2;

FIG. 4A illustrates the vertical width transformation of the graphic character of FIG. 2;

FIG. 4B shows vector data of the graphic character after undergoing the transformation of FIG. 4A;

FIG. 5 illustrates an approximate solution of normal vectors according to the present invention;

FIGS. 6A and 6B show examples of graphic characters obtained according to the present invention; and

FIGS. 7A, 7B and 7C show examples of graphic characters obtained according to the prior art.

In view of the above problems, it is an object of the present invention to provide an image processing system comprising discriminating means for discriminating the signs of a normal vector component of the contour line of a delineative pattern such as a picture image.

It is another object of the present invention to provide an image processing system capable of independently changing the widths of an image (pattern) along the vertical and horizontal directions and which, when applied to a character, can provide various patterned characters easy to read.

It is a further object of the present invention to provide an image processing system capable of changing the widths along the desired directions by performing a predetermined calculation of the component of a normal vector, taking its sign into consideration.

The embodiment of the present invention will now be described with reference to the accompanying drawings. In the image processing system of the present invention, the objects to be processed may include an image, graphic pattern, graphic character and the like. Obviously, the system may be constructed of a composite apparatus or a unitary apparatus.

FIG. 1 is a block diagram showing the embodiment of the image processing apparatus of the present invention. In the Figure, reference numeral 1 represents a vector processor, reference numeral 2 represents a vector data memory, reference numeral 3 represents a pattern generator, and reference numeral 4 represents a temporary pattern memory.

Character (or image) data in the form of vector data is stored in the vector data memory 2. The vector processor 2 receives an execution command from an external circuit and reads necessary data from the vector data memory 2. The vector processor 2 processes the read-out vector data to obtain necessary data which in turn sent to the pattern generator 3. The pattern generator 3 develops the vector data as numerical data into an actual vector pattern and write it into the temporary pattern memory 4. The written pattern is then read out to an external circuit as a processed data output.

The contour of a graphic character is represented by a vector data point train shown by o symbols, linear line segments and or curved line segments being interposed between points.

The direction of each vector data, and hence the order of each point is arranged as shown by arrows so that the inside of the graphic pattern (inside of the contour) is always located to the right side relative to the direction of each vector data.

The normal vectors at respective points are shown in FIG. 3. As seen from FIG. 3, the normal vectors are directed to the outside of the contour, which results from the above-noted order of each point.

To make broader only the width along the vertical direction of the pattern, only the sign of the x component of each normal vector is to be noticed and the point is moved by a predetermined amount in the direction of the x component of the normal vector. An example of the character thus processed by moving the points of FIG. 2 character is shown in FIG. 4.

In FIG. 4A illustrating the process of making broader the width, o symbols represent the points before the process while .DELTA. symbols represent the points after the process. FIG. 4B shows the contour of the character thus obtained. Alternatively, to make narrow the width along the vertical direction of the pattern, the point is moved in the direction opposite to that of the x component of the normal vector. Similarly, as to the width along the horizontal direction of the pattern, only the signs of the y component of the normal vector is taken into consideration for widening or narrowing the width.

With the above processes, it is possible to independently make broader or narrower the widths along the vertical and horizontal directions of the contour of a graphic character. It is noted that the direction of movement of the point train of the vector data depends only upon the signs of the x and y components of the normal vectors. Therefore, it is not necessary to use a precise normal vector for each point, but an approximate value can be employed using a simplified algorithm.

An approximate solution of a normal vector applied to the present embodiment will be described with reference to FIG. 5. FIG. 5 shows vector data point train P.sub.n-1 (x.sub.n-1, y.sub.n-1), P.sub.n (x.sub.n, y.sub.n) and P.sub.n+1 (x.sub.n+1, y+1), and vectors V.sub.n and V.sub.n+1 interconnecting the points.

The relation between each points and vectors V.sub.n and V.sub.n+1 can be expressed in the following equations:

Assuming here that tangent vector t.sub.1 is defined as having the same angle .alpha. and .beta., tangent vector t.sub.1 can be expressed in the following equation because the half of the angle between vectors V.sub.n+1 and V.sub.n are obtained by adding the unit vectors thereof:

Normal vector (unit vector n perpendicular to tangent vector t(t.sub.x, t.sub.y) and directing to the left side relative to the direction of vectors, is given by:

Therefore, from the equations (1), (2) and (3):

where

The approximate normal vector can be solved as above. In this case, if the width only along the vertical direction of the pattern is processed, the y component of the normal vector is not needed, or vice versa.

After the graphic character is subjected to the above widening or narrowing process, transformation such as magnification, reduction or rotation is carried out. Examples of such transformation applied to the character shown in FIG. 7A are shown in FIGS. 6A and 6B, wherein the magnified character with broadened width along the vertical direction is shown in FIG. 6A, and the magnified character with narrowed width along the horizontal direction is shown in FIG. 6B.

As seen from the foregoing description of the present invention, it is possible to independently changing the widths along the vertical and horizontal directions of a delineative pattern (e.g., graphic pattern) by discriminating the signs of the normal vector and moving the contour line data. Further, application of the present invention to characters enables various patterned characters easy to read.