JP2005339370A - Image processing apparatus and image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a drawing speed without lowering a drawing quality when drawing data in which a number of small curves are specified. <P>SOLUTION: An image processing apparatus comprises: a first curvelinear transformation part 21 for converting a specified curve into one or a plurality of linear lines on the basis of the starting point, control point and end point thereof, and also for repeating the segmentation of the linear lines until the one or the plurality of converted linear lines are approximated to the specified curve; a second curvelinear transformation part 22 for converting the specified curve into the plurality of linear lines connecting the starting point, control point and end point; and a curvelinear transformation decision part 23 for deciding whether the specified curve is sufficiently small, and also for applying the second curvelinear transformation part 22 when the specified curve is sufficiently small, and applying the first curvelinear transformation part 21 when the specified curve is not sufficiently small. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus and an image processing program for converting a specified curve into one or a plurality of straight lines approximated thereto and drawing the converted curve.

  A Bezier curve described by vector data is known. A Bezier curve is a function curve that is uniquely derived from the coordinates of the start point, control point, and end point. Since various curves can be described with a small amount of data, it is widely used for outline font curve description, CAD free curve description, etc. It has been.

  When drawing a Bezier curve on a print medium or display, usually, a curve conversion process for converting the Bezier curve into one or more straight lines approximated thereto, and a predetermined drawing of the converted one or more straight lines. In accordance with the rules, processing to expand on the bitmap memory is performed. In particular, since the process of converting a Bezier curve to an approximate straight line has a great influence on the drawing quality and the drawing speed, various linear approximation methods have been proposed (see, for example, Patent Document 1).

FIG. 5 is an explanatory diagram showing a linear approximation method of a Bezier curve according to a conventional example.
In the straight line approximation method shown in this figure, first, it is determined whether or not the straight line 101 connecting the start point P1 and the end point P4 of the curve 100 is approximate to the curve 100 (FIG. 5A).

  If it is determined that the approximation is not performed, the midpoint 103 of the straight line 102 connecting the start point P1 and the first control point P2, the midpoint 105 of the straight line 104 connecting the first control point P2 and the second control point P3, The midpoint 107 of the straight line 106 connecting the second control point P3 and the end point P4, the midpoint 109 of the straight line 108 connecting the midpoints 103 and 105, the midpoint 111 of the straight line 110 connecting the midpoints 105 and 107, and the midpoint The midpoint 113 of the straight line 112 connecting 109 and 111 is obtained. The straight line 112 is a tangent to the curve 100, and the curve 100 can be divided into two arcs 100 a and 100 b by the midpoint 113. Next, a straight line 114 connecting the start point P1 and the midpoint 113 and a straight line 115 connecting the midpoint 113 and the end point P4 are obtained, and it is determined whether these straight lines 114 and 115 approximate the curve 100 (FIG. 5B). )).

If it is determined that the approximation is not made, the midpoints 116 and 117 of the arcs 100a and 100b are obtained by the above procedure, and the straight lines 118 to 121 connecting the start point P1, the midpoints 116, 113, 117, and the end point P4 are obtained. It is determined whether these straight lines 118 to 121 approximate the curve 100 (FIG. 5C).
That is, the straight line approximation method includes a step of dividing a straight line to be replaced by a curve and a step of determining the approximation, and repeats these steps until a straight line approximating the curve is obtained.
JP 7-6232 A

  However, the conventional image processing apparatus has a problem that it takes time to draw because the above-described linear approximation method is applied to all the specified curves. In particular, when developed in a bitmap memory, if many small curves are specified that fit within two or three dots vertically and horizontally, the delay in drawing is significant.

  The present invention has been considered in view of the above circumstances, and an image processing apparatus and an image processing program capable of improving drawing speed without degrading drawing quality when drawing data in which a large number of small curves are designated. The purpose is to provide

  In order to achieve the above object, an image processing apparatus of the present invention includes a curve designating unit that designates a start point, a control point, and an end point of a curve, and a curve processing unit that converts the designated curve into one or more straight lines approximated thereto. And a drawing unit that draws the converted one or more straight lines, wherein the curve processing unit is configured to select a specified curve based on a start point, a control point, and an end point. A first curve conversion unit that converts a plurality of straight lines and repeats subdivision of the straight line until the converted one or more straight lines approximate the specified curve, and the specified curve at its start point, A second curve conversion unit that converts a plurality of straight lines connecting the control point and the end point, and whether or not the specified curve is sufficiently small, and when the specified curve is sufficiently small, the second curve Apply conversion part, otherwise When has a configuration and a curved conversion determination unit for applying said first curve converter.

In this way, when the specified curve is sufficiently small, the time required for the curve conversion process is shortened by converting the specified curve into a plurality of straight lines connecting the start point, the control point, and the end point. . Thereby, when drawing data in which a large number of small curves are specified, the drawing speed can be dramatically improved.
In addition, since this curve conversion process is applied only when the specified curve is sufficiently small, it is possible to avoid a reduction in drawing quality.

Further, the image processing apparatus of the present invention has a specified curve when the distance between the start point and the end point is within a predetermined distance and all the control points are included in a rectangular area whose diagonal is the start point and the end point. The configuration is determined to be sufficiently small.
In this way, it is possible to accurately determine a curve whose drawing quality does not deteriorate due to the application of the second curve conversion unit.

Further, the image processing apparatus of the present invention applies the first curve conversion unit even when the specified curve is sufficiently small when the start point, the control point, and the end point of the specified curve satisfy predetermined exception conditions. It is as composition to do.
In this way, only the first curve conversion unit can be excluded from the application target of the second curve conversion unit, with the exception of curves that cause differences in drawing results due to the application of the second curve conversion unit. The same drawing result as that obtained by converting using can be obtained.

The image processing program of the present invention specifies the start point, the control point, and the end point of the curve, converts the specified curve into one or more straight lines approximated thereto, and converts the converted one or more straight lines. An image processing program that causes an image processing apparatus to execute a drawing process, and when a specified curve is converted into one or more straight lines, a process for determining whether the specified curve is sufficiently small and a specified When the curve is sufficiently small, the specified curve is converted into a plurality of straight lines connecting the start point, the control point, and the end point. Otherwise, the specified curve is converted to the start point, the control point, and the control point. Based on the end point, the image processing apparatus performs conversion to one or a plurality of straight lines, and repeats segmentation of the straight lines until the converted one or more straight lines approximate a specified curve. There as formed.
In this way, the present invention can be provided as an image processing program.

  As described above, according to the present invention, when the specified curve is sufficiently small, the specified curve is converted into a plurality of straight lines connecting the start point, the control point, and the end point, so that many small curves are specified. When drawing data, the drawing speed can be dramatically improved without degrading the drawing quality.

Embodiments of the present invention will be described below with reference to the drawings.
A configuration of an image processing apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a schematic configuration diagram of an image processing apparatus according to an embodiment of the present invention.
However, although the image processing apparatus shown in FIG. 1 shows the configuration of a printer (image processing unit) as a specific example, the image processing apparatus of this embodiment is not limited to a printer. Digital multifunction devices (multifunction peripherals (MFPs)), computers and the like.

  Further, when the image processing apparatus of the present embodiment is a printer, the printer includes various printing methods such as an inkjet printer, a sublimation type thermal transfer printer, a dot impact printer, a laser printer, and a fusion type thermal transfer printer. Includes a printer.

As shown in FIG. 1, the image processing apparatus according to the present embodiment includes a curve designating unit 10, a curve conversion processing unit 20, and a drawing unit 30.
The curve designation unit 10 inputs the coordinate data of the start point, the control point, and the end point, and designates the curve.

  The curve conversion processing unit 20 is a part that converts a designated curve into one or a plurality of straight lines approximated thereto, and includes a first curve conversion unit 21, a second curve conversion unit 22, and a curve conversion determination. Part 23.

  The first curve conversion unit 21 converts the designated curve into one or more straight lines based on the start point, the control point, and the end point, and the converted one or more straight lines are designated as the designated curve. Repeat subdivision of the line until approximating to. As the curve conversion method used by the curve conversion unit 21, a known linear approximation method can be applied. For example, the linear approximation method shown in FIG. 5 is used.

  The second curve conversion unit 22 converts the designated curve into a plurality of straight lines connecting the start point, the control point, and the end point. The curve conversion process by the curve conversion unit 22 can be performed in a shorter time than the first curve conversion unit 21.

  The curve conversion determination unit 23 determines whether or not the specified curve is sufficiently small. When the specified curve is sufficiently small, the second curve conversion unit 22 is applied. One curve conversion unit 21 is applied. A specific determination method of the curve conversion determination unit 23 will be described later.

  The drawing unit 30 draws one or more straight lines converted by the curve conversion processing unit 20. Specifically, the converted one or more straight lines are developed on the bitmap memory according to a predetermined drawing rule.

FIG. 2 is a flowchart showing an overall processing procedure (image forming method) of the image processing apparatus according to the embodiment of the present invention.
As shown in this figure, after specifying the curve (S1), the image processing apparatus determines whether the specified curve is sufficiently small (S2). If this determination result is YES, it is further determined whether or not the specified curve satisfies the exception condition (S3). When this determination result is NO, the designated curve is converted into a straight line by the second curve conversion unit 22 (S4). On the other hand, when step S2 is NO or when the determination result of step S3 is YES, the designated curve is converted into a straight line by the first curve conversion unit 21 (S5). Thereafter, the converted straight line is drawn (S6), and the process ends.
The above steps (S1 to S6) are repeated until all the curves included in the data to be drawn are designated.

Next, a specific determination method in steps S2 and S3 will be described with reference to FIGS.
FIG. 3 is an explanatory diagram showing a minute curve determination method of the image processing apparatus according to the embodiment of the present invention, and FIG. 4 is an explanatory diagram showing an exceptional curve determination method of the image processing apparatus according to the embodiment of the present invention.
However, the grid shown in these figures is a grid indicating the interval between the drawn dots.

  In step S2, it is first determined whether the distance between the starting point P1 and the ending point P4 of the curve is very small. The reference distance is such a small distance that the difference between the drawing result by the first curve conversion unit 21 and the drawing result by the second curve conversion unit 22 is not visually felt. This will vary depending on the resolution of the drawing device. For example, in a printer with a resolution of 300 to 600 dpi, if the distance between the start point P1 and the end point P4 is within 2 dots in length and width, there is no visual difference, so the curve is determined based on this distance.

  If it is determined that the distance between the start point P1 and the end point P4 is very small, it is next determined whether or not the control points P2 and P3 are included in a rectangular area whose diagonal is the start point P1 and the end point P4. Even if the distance between the start point P1 and the end point P4 is very small, if the control points P2 and P3 are outside the rectangular area, the drawing result by the first curve conversion unit 21 and the second curve conversion unit This is because there is a visual difference in the drawing result of No. 22.

  In other words, in the present embodiment, when the distance between the start point P1 and the end point P4 is within a predetermined distance, and all the control points P2 and P3 are included in a rectangular area whose diagonal is the start point P1 and the end point P4, The determined curve is determined to be sufficiently small and the second curve conversion unit 22 is applied, otherwise the first curve conversion unit 21 is applied.

  In step S3, even if it is determined that the designated curve is sufficiently small, a curve in which there is a difference between the drawing result by the first curve converting unit 21 and the drawing result by the second curve converting unit 22 is used. This determination is strictly made and excluded from the processing target of the second curve conversion unit 22, and the determination condition changes according to the drawing rule of the drawing unit 30.

For example, in the coordinates of the grid unit as shown in FIG. 4, when there is a drawing target in an area of X1 or more and less than X2 and Y1 or more and less than Y2, one dot is placed on the coordinates (X1, Y1). ”Is set, the curve defined by the start point P1, the control points P2, P3, and the end point P4 as shown in FIG. When the second curve conversion unit 22 performs linear conversion and draws, as shown in FIGS. 4B and 4C, there is a difference in the drawing result.
Therefore, in this embodiment, after the determination in step S2, it is determined whether the control points P2 and P3 are on Y1 or X2. If the control points P2 and P3 are on Y1 or X2, the first curve is obtained even if the curve is very small. The conversion unit 21 is applied.

  According to the image processing apparatus of the present embodiment configured as described above, the specified curve is converted into one or a plurality of straight lines based on the start point, the control point, and the end point, and the converted one or The first curve converting unit 21 that repeats subdivision of the straight line until the plurality of straight lines approximate the designated curve, and the designated curve is converted into a plurality of straight lines connecting the start point, the control point, and the end point. The second curve conversion unit 22 determines whether or not the specified curve is sufficiently small. When the specified curve is sufficiently small, the second curve conversion unit 22 is applied, otherwise. And a curve conversion determination unit 23 to which the first curve conversion unit 21 is applied. Therefore, when the specified curve is sufficiently small, the time required for the curve conversion process is shortened without causing a visual difference. be able to. This makes it possible to dramatically improve the drawing speed when drawing data in which a large number of small curves are designated.

  In addition, the curve conversion determination unit 23 determines that the specified curve is sufficient when the distance between the start point and the end point is within a predetermined distance and all the control points are included in the rectangular area whose diagonal is the start point and the end point. Therefore, it is possible to accurately determine a curve whose drawing quality is not deteriorated by the application of the second curve conversion unit 22.

  In addition, the curve conversion determination unit 23 applies the first curve conversion unit 21 even when the specified curve is sufficiently small when the start point, the control point, and the end point of the specified curve satisfy predetermined exception conditions. Therefore, a curve in which the drawing result is different due to the application of the second curve conversion unit 22 can be an exception and can be excluded from the application target of the second curve conversion unit 22, and as a result, the first curve conversion unit 21 can be excluded. The same drawing result can be obtained as in the case of conversion using only.

Next, the image processing program will be described.
The drawing function of the image processing apparatus in the above embodiment is realized by an image processing program stored in a storage unit (not shown) such as a ROM.
The image processing program is read by a CPU or the like (computer) in the image processing apparatus to send a command to each component of the image processing apparatus, and performs predetermined processing, for example, curve designation processing of the curve designation unit, curve conversion determination Curve conversion determination processing of a part, curve conversion processing of a curve conversion part, etc. are performed.
Thus, the drawing function is realized by an image processing apparatus in which an image processing program and a computer cooperate.

Note that the image processing program for realizing the drawing function can be stored in a computer-readable recording medium such as an external storage device and a portable recording medium in addition to being stored in a computer ROM or hard disk. .
The external storage device refers to a memory expansion device that incorporates a storage medium such as a CD-ROM and is externally connected to the image processing apparatus. On the other hand, the portable recording medium is a recording medium that can be mounted on a recording medium driving device (drive device) and is portable, and refers to, for example, a flexible disk, a memory card, a magneto-optical disk, and the like.

The program recorded on the recording medium is loaded into the RAM of the computer and executed by the CPU. By this execution, the function of the image processing apparatus of the present embodiment described above is realized.
Further, when the image processing program is loaded by the computer, the image processing program held by another computer can be downloaded to its own RAM or external storage device using a communication line. The downloaded image processing program is also executed by the CPU, and realizes the drawing function of the image processing apparatus of the present embodiment.

  The present invention is applied to an image processing apparatus that converts a specified curve into one or a plurality of straight lines approximated to the specified curve and draws it. For example, it can be suitably used for a printer, a copier, a facsimile machine, a scanner, a digital composite apparatus, a computer, and the like.

1 is a schematic configuration diagram of an image processing apparatus according to an embodiment of the present invention. 3 is a flowchart illustrating an overall processing procedure of the image processing apparatus according to the embodiment of the present invention. It is explanatory drawing which shows the micro curve determination method of the image processing apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the exceptional curve determination method of the image processing apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the linear approximation method of the Bezier curve concerning a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Curve designation | designated part 20 Curve conversion process part 21 1st curve conversion part 22 2nd curve conversion part 23 Curve conversion determination part 30 Drawing part P1 Start point P2 1st control point P3 2nd control point P4 End point

Claims (4)

A curve designating unit for designating the start point, control point, and end point of the curve, a curve conversion processing unit for transforming the designated curve into one or more straight lines approximated thereto, and drawing the transformed one or more straight lines An image processing apparatus comprising a drawing unit,
The curve processing unit is
The specified curve is converted into one or more straight lines based on the start point, control point, and end point, and the straight line is subdivided until the converted one or more straight lines approximate the specified curve. A first curve conversion unit that repeats
A second curve conversion unit that converts the specified curve into a plurality of straight lines connecting the start point, the control point, and the end point;
It is determined whether the specified curve is sufficiently small, and when the specified curve is sufficiently small, the second curve conversion unit is applied, and otherwise, the first curve conversion unit is applied. An image processing apparatus comprising: a curve conversion determination unit to be applied.   When the distance between the start point and the end point is within a predetermined distance and all the control points are included in a rectangular area having the start point and the end point as a diagonal, it is determined that the specified curve is sufficiently small. The image processing apparatus according to claim 1.   The first curve conversion unit is applied even when the specified curve is sufficiently small when the start point, the control point, and the end point of the specified curve satisfy predetermined exception conditions. 3. The image processing apparatus according to 3. The start point, control point, and end point of the curve are specified, the specified curve is converted into one or more straight lines approximated thereto, and the image processing apparatus is caused to execute processing for drawing the converted one or more straight lines. An image processing program,
A process of determining whether the specified curve is sufficiently small when converting the specified curve into one or more straight lines;
When the specified curve is sufficiently small, a process of converting the specified curve into a plurality of straight lines connecting the start point, the control point, and the end point;
Otherwise, the specified curve is converted into one or more straight lines based on the start point, control point, and end point, and the converted one or more straight lines approximate the specified curve. An image processing program that causes an image processing apparatus to execute a process of repeating segmentation of a straight line up to.

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