JP2774573B2 - Image processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image processing method.

<Prior Art> Conventionally, as an image processing method, an outline of a figure is represented by an outline vector, an outline is created from this outline vector by raster conversion, and the inside of the outline is painted out by a switching drawing method (unexpected method). There is a way.

As shown in FIG. 2, the odd detection method scans in the X-axis direction, starts filling at odd-numbered intersections between outlines and horizontal scanning lines, and stops filling at even-numbered intersections. Is the way.

Further, as a method of creating an outline by raster conversion from an outline vector, there is a method using a well-known Bresenham algorithm.

FIG. 3 is a diagram showing an example of an outline vector, and FIG.
The figure shows an outline created by the method using the Bresenham algorithm for the vector C in FIG. 3, and FIG. 7 is a flowchart showing the method using the Bresenham algorithm.

Hereinafter, a procedure for creating the outline of FIG. 4 from the vector C of FIG. 3 will be described with reference to the flowchart of FIG.

First, in step S71, the starting point of the vector C (xc1, yc1)
The absolute value of the difference between the X-coordinates of the point and the end point (xc2, yc2) is set to “deltax”, and the absolute value of the difference between the Y-coordinates is set to “deltay”. Then, in step S72, if "deltax" is larger than "deltay", the process proceeds to step S73 with the X axis as the major axis, and if smaller, the Y axis proceeds to the major axis flow. Step S7
In step 3, an initial value of e and constants (cons1, cons2) are set. This e is, for example, the next time the process proceeds to step S83.
= Cons2-deltax, where e = cons2-deltax is e
= 2 * de on both sides to convert deltay / deltax-0.5 to an integer
2 * deltax * e is newly set to e by multiplying ltax. That is, e> 0 means that the Y coordinate of the intersection of the vector and a straight line parallel to the Y axis passing through the X coordinate of the display point of the pixel is one more increment (or decrement) of Y than the Y coordinate of the display point. It is close to the Y coordinate of the indicated display point. Next, from step S74 to step S78
Alternatively, the process proceeds to step S79, where the value is incremented (inc = 1) or decremented (i
nc = -1). Then, in step S80, the start point of the vector is set as the first display point of the pixel. Next, in step S81, it is determined whether or not e> 0. If not e> 0, e = e + cons2 is set in step S83. Then, in step S84, a pixel (vicel) is displayed at the display point. If> 0, Y is incremented (decremented) by one in step S82 and e = e + cons1, and then in step S84, a pixel is displayed at the display point where Y is incremented (decremented). Then, in step S85, X is incremented by one (decrement).
Then, the process returns from step S86 to step S81, and the same processing is performed up to the end point of the vector.

By the above processing, the vector C shown in FIG.
The outline shown in the figure is created.

However, even if drawing is performed based on this outline by the odd method shown in FIG. 2, scanning stops at the pixel indicated by ○, and the inside of the outline cannot be painted. Therefore, conventionally, a 3 × 3 mesh filter is scanned in the + direction of the X axis so that the center of the filter is located above each pixel shown in FIG. 4, and the pattern of the matrix is shown in FIG. When the pattern becomes the same as any of the patterns shown, the center pixel is drawn, and when the pattern becomes different from the pattern shown in FIG. Pixels are removed. For example, if the above filter is applied to the leftmost pixel in FIG. 4, the pattern is equal to the lower left pattern in FIG. 5, so that pixel is drawn. Since the pattern on the right pixel does not have the pattern shown in FIG. 5, the pixel is not drawn. In this way, pixels marked with a cross in the circle are drawn and pixels in the circle are not drawn. The pattern in FIG. 5 is used for a vector in the direction in which Y decreases like the vector C, and the pattern in FIG. 6 is used for a vector in the direction in which Y increases. When the Y-axis is the major axis, the outline does not become as shown in FIG. 4, so that it is not necessary to use the filter.

<Problem to be Solved by the Invention> As described above, in the above-described conventional image processing method, when the X axis is the major axis, the processing by the Bresenham algorithm is performed, and then the 3 × 3 mesh filter is used. There is a problem that the processing has to be performed and the processing takes time.

Accordingly, it is an object of the present invention to provide an image processing device which draws an outline which does not include unnecessary pixels as shown in FIG. It is to provide a method.

<Means for Solving the Problems> In order to achieve the above object, the present invention relates to an image processing method for representing an outline of a figure by an outline vector and creating an outline from the outline vector. A pixel candidate point is determined based on the vector, and the outline vector is a vector that increases in the X-axis direction and increases in the Y-axis direction, or is a vector that decreases in the X-axis direction and decreases in the Y-axis direction, and If the absolute value of the change amount in the X-axis direction is a vector larger than the absolute value of the change amount in the Y-axis direction, the pixel candidate point changes its Y coordinate with respect to the immediately preceding pixel candidate point. In this case, the previous pixel candidate point is drawn while the pixel candidate point does not change its Y coordinate with respect to the immediately preceding pixel candidate point. In this case, the previous pixel candidate point is not drawn, and the outline vector is a vector that increases in the X-axis direction and decreases in the Y-axis direction, or decreases in the X-axis direction and If the pixel candidate point is a vector that increases in the direction and the absolute value of the amount of change in the X-axis direction is larger than the absolute value of the amount of change in the Y-axis direction, If the Y coordinate changes with respect to the candidate point, the pixel candidate point is drawn. If the Y coordinate does not change with respect to the immediately preceding pixel candidate point, the pixel candidate point is drawn. Is not drawn, and the outline vector is X
If the absolute value of the amount of change in the axial direction is a vector that is not greater than the absolute value of the amount of change in the Y-axis direction, all the pixel candidate points obtained above are drawn, and successive pixel candidate points are drawn. An outline is created by identifying a non-drawing.

<Operation> In the case where the outline of a figure is represented by an outline vector, in order to create an outline from the outline vector, first, for each outline vector, the absolute value of the amount of change in the X-axis direction is the absolute value of the amount of change in the Y-axis direction. It is determined whether it is larger than the value. If the absolute value of the change amount in the X-axis direction is not greater than the absolute value of the change amount in the Y-axis direction, an outline is created based on the Bresenham algorithm using the Y axis as the major axis. On the other hand, when the absolute value of the change amount in the X-axis direction is larger than the absolute value of the change amount in the Y-axis direction, the following processing is performed using the X axis as the major axis. That is, if the outline vector is a vector that increases in the X-axis direction and increases in the Y-axis direction, or is a vector that decreases in the X-axis direction and decreases in the Y-axis direction, the Bresenham algorithm is used. A pixel candidate point is calculated based on the newly calculated pixel candidate point, and if the Y coordinate changes with respect to the immediately preceding pixel candidate point, the immediately preceding pixel candidate point is drawn. If the Y coordinate of the candidate point has not changed with respect to the immediately preceding pixel candidate point, the immediately preceding pixel candidate point is not drawn. On the other hand, if the outline vector is X
If the vector is a vector increasing in the axial direction and decreasing in the Y-axis direction, or a vector decreasing in the X-axis direction and increasing in the Y-axis direction, a pixel candidate point is calculated based on the Bresenham algorithm. If the Y coordinate of the newly obtained pixel candidate point has changed with respect to the immediately preceding pixel candidate point, the pixel candidate point is drawn, while the newly obtained pixel candidate point is changed to the immediately preceding pixel candidate point. If the Y coordinate does not change, the pixel candidate point is not drawn. In this manner, outlines are sequentially created by sequentially identifying drawing and non-drawing of pixel candidate points.

As described above, since the outline can be created without performing the filter processing as in the conventional example, the processing time is shortened.

<Example> Hereinafter, the present invention will be described in detail with reference to an illustrated example.

FIG. 1 is a flowchart showing the processing contents of this embodiment using a microcomputer.

In FIG. 1, the processing contents from step S1 to step S10 are the same as the processing contents from step S71 to step S80 in FIG. When the Y axis is the major axis, an outline is created based on the usual Bresenham algorithm.

When the processes from step S1 to step S10 are completed, the process proceeds to step S11. In step S11, inc = 1
And incx = 1, that is, the vector is X
When increasing in the axial direction and increasing in the Y-axis direction (in the case of rising to the right), or when inc = 1 and incx =
-1, ie, the vector decreases in the X-axis direction,
If it decreases in the Y-axis direction (downward to the left), the process proceeds to step S12; otherwise, the process proceeds to step S12.
Go to 19.

In step S12, it is determined whether or not e> 0. Then, e> 0, that is, the Y coordinate of the vector at the X coordinate of the display point of the pixel is larger than the Y coordinate of the display point by Y.
If it is close to the Y coordinate of the display point that has been incremented (or decremented) by one, the process proceeds to step S13, and the pixel is drawn at the display point whose X coordinate is immediately before. Then, the process proceeds to step S14, where Y is incremented (decremented) by one and e = e + cons1.
And X is incremented (decremented) by one. On the other hand, if e> 0 is not satisfied in step S12, no pixel is drawn at that display point, e = e + cons2 is set in step S15, and then X is incremented (decremented) by one in step S16. Then, from step S17 to step S
Returning to 12, the same processing is performed up to the end point of the vector.
Since the pixel is not drawn at the end point of the vector as it is, drawing is always performed in step S18.

On the other hand, in step S19, after drawing the first pixel, the process proceeds to step S20 to determine whether e> 0. When e> 0, the process proceeds to step S21,
Increment Y by one (decrement) and e
= E + cons1, and then the pixel is drawn at the display point where Y is incremented (decremented) by one. Then, the process proceeds to step S24, where X is incremented (decremented) by one. On the other hand, if e> 0 is not satisfied in step S20, no pixel is drawn at that display point, and in step S23, e =
After e + cons2, X is incremented (decremented) by one in step S24. Then, the process returns from step S25 to step S20, and the same processing is performed until the end point of the vector.

As described above, by performing the above-described processing, it is possible to create an outline similar to the case of using a 3 × 3 mesh filter in the conventional example. Therefore, processing time is not required as in the case where the above-described filter is used, and the processing can be speeded up.

<Effects of the Invention> As is clear from the above, according to the image processing method of the present invention, an outline can be created without performing the filter processing as in the conventional example, so that the processing time is shortened and the processing time is reduced. Higher speed can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart showing the processing contents when an outline is created from a vector in one embodiment of the present invention; FIG. 2 is a diagram for explaining a switching drawing method (odd occurrence method); FIG. 4 is a diagram showing an example in which the outline of a figure is displayed by a vector, FIG. 4 is a diagram showing an outline created based on the conventional Bresenham algorithm for the vector C in FIG. 3, FIG. 5 and FIG. FIG. 7 is a diagram showing a matrix pattern used for filter processing in the conventional example, and FIG. 7 is a flowchart showing the processing contents when an outline is created from a vector in the conventional example.

Claims (1)

(57) [Claims] 1. An image processing method for expressing a contour of a figure by an outline vector and generating an outline from the outline vector, wherein pixel candidate points are obtained from the outline vector based on Bresenham's algorithm. Or a vector that increases in the Y-axis direction, or a vector that decreases in the X-axis direction and decreases in the Y-axis direction, and the absolute value of the amount of change in the X-axis direction is In a case where the pixel candidate point is larger than the absolute value of the amount of change, the pixel candidate point draws the immediately preceding pixel candidate point when the Y coordinate changes with respect to the immediately preceding pixel candidate point. If the pixel candidate point does not change its Y coordinate with respect to the immediately preceding pixel candidate point, the preceding pixel candidate point is not drawn, The line vector is a vector that increases in the X-axis direction and decreases in the Y-axis direction, or a vector that decreases in the X-axis direction and increases in the Y-axis direction, and the absolute amount of change in the X-axis direction is If the value is a vector larger than the absolute value of the amount of change in the Y-axis direction, the pixel candidate point is drawn if the Y coordinate changes with respect to the immediately preceding pixel candidate point. On the other hand, if the pixel candidate point does not change its Y coordinate with respect to the immediately preceding pixel candidate point, the pixel candidate point is not drawn, and the outline vector indicates the absolute amount of change in the X-axis direction. If the value is a vector that is not larger than the absolute value of the change amount in the Y-axis direction, all the pixel candidate points determined above are drawn, and the drawing and non-drawing of the pixel candidate points are sequentially identified and the outline is drawn. To create It features and to an image processing method.