JP2000222569A - Plotter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly and easily output a gray scale level from an edge list in the stage where a multi-level and high-resolution output is generated from outline information. SOLUTION: An input part 11 receives outline information from a client to generate an enlarged outline for pixel segments. A scan conversion part 12 detects intersections between scanning lines and the enlarged outline to generate an edge list for pixel segments. A gray scale generation part 13 receives the edge list from the scan conversion part 12 with respect to each scanning line and calculates the number of pixel segments, which are inverted on the scanning line, and accumulates respective pixel segments of each pixel in a corresponding array in an image buffer 15. After accumulation of the number of inverted pixel segments is terminated for scanning lines corresponding to the magnification, the array in the image buffer 15 indicates the number of pixel segments inverted in the pixel, and the gray scale level of the pixel is determined based on this number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for receiving drawing target information such as characters and figures as outline information.
A drawing device that can output a character or graphic pattern of any size to a page printer or a CRT display. Particularly, efficiently executes grayscale drawing with a small amount of hardware resources to improve the visibility of the outline of the pattern. It is made possible.

[0002]

2. Description of the Related Art In an output device based on a bitmap screen (raster screen) such as a page printer and a display, as the resolution increases, more data is required to display characters and graphics of the same size. . For character information having a fixed outline, it is inefficient to have bitmap data for each size, so it is advantageous to fill out the outline of the character after enlarging or reducing the outline information. In addition, the current mainstream P
In a printer or the like using a DL (Page Description Language), graphic information is also input in an outline, so that the data transfer time between input / output devices is reduced, and it is no longer necessary to be aware of the resolution of the printer.

However, in order to directly generate bitmap information from outline information, a vertical x
A memory area corresponding to the horizontal size is required, and when a large-sized or high-resolution display device is used, a high-speed processing device and an increased memory capacity are required. For example, if the outline is multiplied N times vertically and horizontally, a memory of N square is required. This puts pressure on the manufacturing cost of the output device.

[0004] Further, with the increase in the definition of the output device, the number of gradations and colors has been increased. There is a method of making the jaggy less noticeable by arranging an intermediate color on the outline of a character or a figure by utilizing this. In particular, when a character or the like is displayed in a single color, it is called a gray scale. Adopting gray scale for characters not only improves output quality, but also improves readability of small-size characters such as ruby. In general, the color density of a pixel of an intermediate color is determined by picking up contour pixels and determining what percentage of the area of each pixel is inside the contour line.

As a method of obtaining the area, a method of dividing each pixel in the vertical and horizontal directions and examining how many of the divided pixels are determined to be inside and inverting (“Basic technology of DTP (5)”, S
upperASCII, Vol. 2, No. 8,199
(August 1st) is well known. FIG. 2 shows an example in which one pixel is divided vertically and horizontally into three, and pixels determined to be inside the outline are inverted to black. When actually calculating, a bitmap is created from an outline enlarged N times vertically and horizontally, and if M pixels in an N × N area are inverted, M / (N ×
N) to determine the area ratio. In this case, the area ratio is 0 /
(N × N) to 1, the gradation accuracy is N × N
+1 gradation. Generally, this process places a heavy load on the CPU to search all the pixels of the enlarged image, and further requires an enlargement process, thus consuming a large amount of memory as described above.

[0006] As a means for obtaining a bitmap from an outline, an algorithm called scan conversion (scan conversion method) is currently common.

FIG. 1 shows an example of scan conversion. In this example, even-odd (EV
The inside and outside of the outline are determined based on a fill condition called an EN-ODD rule.

First, pixels on the intersection between the contour line and each scanning line are extracted. This pixel is called an edge. After the edges have been extracted for all the contour lines, the pixels sandwiched between the edges are inverted for each scanning line. That is, the even-numbered edges are painted from the odd-numbered edges. This is called the even-odd rule. Of course, other rules (zero winding method)
May be used.

The simplest implementation of this processing is to prepare a bitmap of a size that can include a figure as shown in FIG. 4 and invert the pixels that are actually edges. However, when the size of the character is increased or the resolution is high, all pixels must be searched at the painting stage to find an edge, which is disadvantageous in terms of speed. Further, as described above, there is a drawback that a large size requires a large amount of memory. In particular, when it is desired to create a gray scale, the drawback for enlarging becomes significant.

Therefore, as shown in FIG. 5, the edge of each scanning line is managed in a list. . The selected edges are registered in a list for each scanning line, and when all edges are registered, sorting is performed for each list. This list is called an edge list. At the time of output, two points are read from the edge list, and these points are set as a start point and an end point, and the area between them is painted on the frame buffer. In the edge list, for example, even if the outline is expanded to N × N, only N times the memory before the expansion is required. In addition, since each line has a compression format corresponding to the run-length method, memory consumption is further reduced.

In Japanese Patent Application Laid-Open No. 6-168334, a gray scale is created from an edge list created from an enlarged outline, so that memory consumption is extremely reduced. However, when a grayscale edge list is directly generated from an edge list, complicated conditions such as comparison of a start point and an end point in the preceding and succeeding scan lines are performed, and thus processing is slow. Further, the condition determination depends on the gray scale gradation, and a program must be prepared for each required gradation. The more the number of gradations, the more complicated the program and the more difficult the development.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. In the process of creating multi-tone, high-resolution output from outline information of characters and figures, the present invention is directly applied to an edge list. It is another object of the present invention to provide a drawing apparatus which can easily output a gray scale pixel value (gray scale level), can output at high speed, consumes very little memory, and can output an arbitrary gradation. And

[0013]

According to the present invention, in order to achieve the above-described object, the intersection of the outline and the scanning line is determined based on the information of the outline to be drawn such as characters and figures. A drawing device that extracts coordinates and draws pixels between intersections satisfying a predetermined criterion receives the information of the contour line,
Means for generating information of an enlarged contour by primary-transforming coordinate values defining the contour, obtaining an intersection between the enlarged contour and the scanning line, and calculating an ideal point in a pixel based on the information of the intersection. And a pixel value determining means for calculating a grayscale pixel value of the pixel based on an ideal rendering processing area within the pixel.

In this configuration, the ideal drawing processing area in the corresponding pixel is simply calculated from the information of the intersection of the enlarged contour line and the scanning line, and the gray scale level of the pixel is obtained based on this. As a result, the memory consumption is low and there is no need to perform complicated condition judgment. In this configuration, it is also possible to provide a threshold value for the area, to invert the area above the threshold value and not to invert the area below the threshold value, and to perform the binary drawing.

In this configuration, the edge list generated by the scan conversion method can be used as information of the intersection between the enlarged contour and the scan line.

Further, the drawing apparatus further includes an image buffer means for storing the gray scale pixel value in one or a plurality of scanning line units, and an image buffer means for storing the gray scale pixel value in the one or a plurality of scanning line units from the image buffer means. Frame buffer means for receiving the pixel value of the scale may be provided.

Further, the pixel value determining means may have a table means for outputting a gray scale pixel value of a corresponding pixel based on the information of the intersection.

According to the present invention, in order to achieve the above object, coordinates of an intersection of the outline and a scanning line are extracted based on information of an outline to be drawn such as a character or a figure. Drawing processing instruction means for designating whether to perform grayscale drawing processing or binary drawing processing on a drawing apparatus that draws pixels between intersections satisfying a predetermined criterion;
When the grayscale drawing processing is instructed, the information of the outline is received, and a coordinate value defining the outline is linearly transformed to generate information of the enlarged outline, and the grayscale drawing processing is instructed. Then, an intersection between the enlarged contour line and the scanning line is obtained, an ideal drawing processing area in the pixel is calculated based on the information of the intersection, and an ideal drawing processing area in the pixel is calculated. A gray scale pixel value determining means for determining a gray scale pixel value of the pixel, and an image buffer for storing the gray scale pixel value in units of one or a plurality of scanning lines when a gray scale drawing process is instructed. Means, when binary drawing processing is instructed, receives information on the outline to be drawn, finds an intersection between the outline and the scanning line, and obtains information on the intersection. Determining the pixel value of the binary based on 2
The value pixel determining means receives the grayscale pixel value from the image buffer means when the grayscale drawing processing is instructed, and receives the grayscale pixel value from the binary pixel value determining means when the binary drawing processing is instructed. Frame buffer means for receiving binary pixel values may be provided.

Also in this configuration, an ideal drawing processing area in a corresponding pixel is easily calculated from the information of the intersection of the enlarged contour line and the scanning line, and the gray scale pixel value of the pixel is calculated based on this. As a result, the memory consumption is small, and there is no need to perform complicated condition judgment. Further, in this configuration, when binary drawing is sufficient, the processing relating to the binary drawing is directly performed without performing the calculation for gray scale, and the throughput can be improved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, the principle of the present invention will be described.

According to the present invention, the outline is enlarged in accordance with the gradation, and the edge list is created by the scan conversion means. A grayscale image buffer for one line is prepared by the grayscale creating means, and a grayscale image for one line is created from the edge list using a predetermined conversion formula, and then combined with the frame buffer. This is all repeated for the line.

Here, a procedure for outputting a gray scale image of one line of the original size from the edge list of the enlarged contour line will be described by way of an example in which the image is enlarged three times vertically and horizontally to obtain ten gradations. FIG. 2 shows two pixels having the same contour line.
In the case where there is a book, FIG. 3 shows pixels at both ends when the outline is separated to some extent. Each original pixel is divided vertically and horizontally (3
), And performs scan conversion on the divided pixels (referred to as pixel segments). By determining the number of inverted pixel segments in this one pixel, the gradation of the edge can be determined.

Next, a method of calculating the number of inverted pixel segments will be described. First, the example of FIG. 2 (when there are two contour lines in the same pixel) will be described. In FIG. 2, the number of inverted pixel segments per scan line for each pixel is determined by the following equation. The coordinates of the pixel segment used in the calculation are relative coordinates with the left end of the corresponding pixel being 0.

[0024]

## EQU00001 ## where the coordinates of the pixel segment at the end point--the coordinates of the pixel segment at the start point + 1... A However, if there is no pixel segment at the start point in the pixel (in FIG. 2), the coordinates of the pixel segment at the start point =
When the pixel segment to be the end point is not set (0 in FIG. 2), the coordinates of the pixel segment at the end point = the number of divisions−1. The number of segments obtained as described above is calculated for pixel 1
All scan lines included per unit (divided number 3
Therefore, if the addition is performed in three lines), the number of inverted pixel segments per pixel is obtained.

The example of FIG. 2 is calculated.

[0026]

## EQU2 ## = 2-1 + 1 = 2 = 2-0 + 1 = 3 = 2-1 + 1 = 2 ++ = 7 The total number of pixel segments per pixel is 3.times.3 = 9, and the area ratio is 7/9. .

Next, consider the example of FIG. 3 (a case where the outlines are separated to some extent and different outlines intersect two pixels, respectively). By applying the above equation to each scan line of the left pixel, the following is obtained.

[0028]

## EQU00003 ## (the number of divisions-1) -the coordinates of the pixel segment at the starting point + 1 = the number of divisions--the coordinates of the pixel segment at the starting point...

[0029]

The coordinates of the pixel segment at the end point−0 + 1 = coordinates of the pixel segment at the end point + 1... C The pixels sandwiched between the left and right pixels are as follows.

[0030]

## EQU5 ## (the number of divisions-1) -0 + 1 = the number of divisions... D The example of FIG.

[0031]

## EQU6 ## Left pixel = 3-2 = 1 = 3-1 = 2 = 3-1 = 2 ++ = 5 Right pixel = 1 + 1 + 1 = 2 + 1 + 1 = 2 = 0 + 1 = 1 ++ = 5 In most cases, Since the start point and the end point are separated to some extent as shown in FIG. 3, first, the values of the start point and the end point are compared, and A
It is faster to determine whether to calculate using the formulas or to calculate using the B, C, and D formulas than to calculate using only the formula A.

The actual processing is to generate an edge list of pixel segments (divided pixels) from the enlarged outline,
The coordinates of the corresponding pixel are obtained from the quotient obtained by dividing the coordinate value of the pixel segment by the enlargement ratio, the remainder is obtained as the relative coordinates of the pixel segment in the corresponding pixel, the number of inverted pixel segments of each pixel is obtained, and the gray scale is calculated. create.

As described above, in the gray scale creating means of the present invention, since the gray scale is created by calculation and loop, the condition judgment can be minimized, so that the speed is high and the creation procedure does not depend on the number of divisions.

In addition, there are many normally required multiple gradations,
Since there are a few types, a higher speed can be achieved by tabulating the calculation results for each gradation. Since the starting point and the ending point are in most cases distant from each other, most of the calculations by the B, C, and D equations are used. Since formula D is a constant, it is not actually calculated. Since the B and C expressions have only one variable, a small size is sufficient even if a table is created. The left table in FIG. 6 is an example in which the calculation results are previously stored in a table in the case of three divisions of the equation B, and the right table is an equation in the case of division into three equations.

[0035]

Next, an embodiment of the present invention will be described.

FIG. 7 schematically shows the functions of this embodiment. In this drawing, the drawing apparatus of this embodiment includes an input unit 11, a scan conversion unit 12, a gray scale creation unit 13, a synthesis unit 14, an image buffer 15, and a frame buffer 16.

The input unit 11 receives character / graphic outline information from the client, and when gray scale output is instructed, performs primary conversion on each control point of the outline information to create an outline for a pixel segment. . Assuming that the enlargement ratio is N, a gray scale of (N × N) +1 gradations can be handled at most.

The scan converter 12 receives the outline information from the input unit 11, detects an intersection between the scan line and the enlarged contour, and generates an edge list for the pixel segment.

The gray scale creating section 13 first receives the edge list from the scan converting section 12, and initializes the image buffer 15 (one-to-one arrangement with pixels) for one line of pixels. Next, a set of a start point and an end point is sequentially extracted from the edge list of the pixel segment for one scan line, and the relative coordinates of the pixel are calculated. The number of pixel segments to be inverted is calculated by the formula A between the same pixels at the start point and the end point. If the start pixel and the end pixel are different, the number of inverted pixel segments at the start pixel is determined by equation B, the number of inverted pixel segments at the end pixel is determined by equation C, and the start pixel and the end pixel are determined. Equation D calculates the number of inverted pixel segments in the pixels between the pixels. The number of these inverted pixel segments is stored in the image buffer 1
5 are added to the corresponding array. This operation is repeated for N lines in the edge list of the pixel segment to create an image for one line of pixels. Since the value stored in each array is the number of inverted pixel segments in the corresponding pixel, it is converted to a gray scale level by calculation or table conversion.

The synthesizing unit 14 includes the gray scale creating unit 13
And a gray scale image for one line of pixels is received from the frame buffer 16 and combined with the character / graphic display position of the frame buffer 16. When all edge lists have been processed, the process proceeds to an output unit (not shown), and if there is an unprocessed edge list, the process returns to the grayscale creation unit 23.

An output unit (not shown) outputs the information of the frame buffer 16 to a display medium such as paper or a display when the writing of one page into the frame buffer 16 is completed by the synthesizing unit 24.

FIG. 8 shows an example of a computer environment in which this embodiment is realized. In this figure, a CPU (central processing unit) 21, a RAM 2
2, ROM 23, external storage device 24, frame buffer 16, video interface 25, printer interface 26, and the like. Output devices such as a display and a page printer are connected to the video interface 25 and the printer interface 26, and image information (raster information) is read from the frame buffer 16 and supplied to these output devices. CPU
Reference numeral 21 denotes an input unit 11, a scan conversion unit 12, and a scan conversion unit 12 shown in FIG.
The functions of the gray scale creating unit 13 and the synthesizing unit 14 are appropriately executed. Further, outline font data and graphic data are read from the ROM 23 or the external storage device 24, and a part of the information in the RAM 22 is stored in the external storage device 24.
Is written to.

Next, the operation of the drawing apparatus of the embodiment will be described in detail with reference to FIG. 8, FIG. 9 and FIG. In addition,
In this example, gray scale processing and binary processing can be selected.

(Preprocessing) In the scan conversion unit 12, an area of the edge list is secured and each variable is initialized (S3).
0).

(Process of Input Unit 11) The CPU 21 executes the procedure of the input unit 11. First, outline information, character codes, and the like stored in the RAM are read through the interface. If it is a character code, outline information is read from a ROM or an external storage device. When the gray scale is designated, the coordinate transformation of the control point is executed to enlarge the outline (S31, S32). The image buffer 15 of the pixel segment corresponding to one line of the pixel is secured in the RAM 22 (S33).

(Processing of Scan Conversion Unit 12) The CPU 21 executes the procedure of the scan conversion unit 12. As described above, in step S30, an edge list area is secured in the RAM 22 and initialized. Next, determine the number of divisions of the curve,
The outline is divided into short straight lines (S34). Edge selection and registration in the edge list of the RAM are performed on the straight line-divided outline (S35). When the edges of all the contour lines are registered in the edge list, the edge list is sorted for each scanning line (S36). If the gray scale is specified, the process proceeds to step S39 in FIG.

(Processing of Gray Scale Generating Unit 13) CP
U22 executes the procedure of the gray scale creation unit 13.
First, the image buffer 15 (FIG. 7) of the RAM 22 is initialized. Next, the edge list of the number (the number of divisions) required to create one line of pixels is read out from the RAM 22, the number of inverted pixel segments is calculated from each edge list, and added to the image buffer 15. Once the number of inverted pixel segments is determined, the number of pixel segments is converted to a gray scale level.

The specific procedure is as follows. [S39]: The scanning line counter is cleared. [S40]: The image buffer 15 is cleared. [S41]: The edge list of the scanning line counter number is read. [S42]: A pair of a start point and an end point of the edge list is extracted. [S43]: The start point and end point are divided by the number of divisions, and the quotient is set as a new start point and end point. [S44]: It is determined whether the coordinates of the start point and the end point match.
If they match, the process proceeds to step S45. If they do not match, the process proceeds to step S49. [S45]: The calculation result of the expression A is added to the pixel at the start point (also the end point) of the image buffer 15. [S46]: It is determined whether a pair of a start point and an end point still remains. If any remain, the process returns to step S42. If not, the process proceeds to step S47. [S47]: The scanning line counter is incremented. [S48]: It is determined whether or not the scanning line counter is a multiple of the enlargement ratio. If it is a multiple, the process proceeds to step 52. If it is not a multiple, the process returns to step S41 and the process is repeated. [S49]: The result of the expression B is added to the pixel at the start point of the image buffer 15. [S50]: The result of the formula D is added to all pixels immediately after the start point of the image buffer 15 and immediately before the end point. [S51]: The result of the expression C is added to the pixel at the end point of the image buffer 15.

(Processing of Combining Unit) The CPU 22
Follow the steps in First, grayscale level information for one line is written from the image buffer 15 of the RAM 22 to the frame buffer 16 (S52). After the writing, it is determined whether or not all edge lists have been processed (S53). If the processing has been completed, the processing shifts to the processing of the output unit. If there is an unprocessed edge list, the processing returns to the processing of the gray scale creating unit 13 (step S40).

If binary processing is specified instead of gray scale, the scan conversion unit 12 generates an edge list from ordinary contour information (S34 to S36), and the edge list expansion unit 17 (FIG. 11). ), The edge list is directly expanded in the frame buffer 16. That is, the edge list developing unit 17 receives the edge list from the scan conversion unit 22, and stores the
Expand the edge list to the display position of the figure.

(Processing of Output Unit) The output unit checks the frame buffer at fixed time intervals or in response to an end signal from the CPU 22, and outputs a registered bitmap image.

Next, another embodiment of the present invention will be described.

In the above-described embodiment, only an example of gray scale display is shown. However, even in the case of binary display, an image can be created in exactly the same procedure. However, it is not necessary to create an image of pixels for one line in the gray scale creating unit, and the edge list may be directly developed directly at a predetermined position in the frame buffer 16 as shown in step S38. That is, as shown in FIG. 11, the edge list is directly developed in the frame buffer 16 using the edge list developing unit 17. In this way, in the case of binary, the processing of the synthesizing unit 14 can be omitted, so that the speed can be increased. In FIG. 11, parts corresponding to those in FIG. 7 are denoted by corresponding reference numerals. Reference numeral 18 denotes a display instruction unit for instructing gray scale display and binary display.

In the embodiment, the image buffer 15 for one line is used in the gray scale creating unit 13, but is not always necessary when the frame buffer 16 can be read. By reading and writing directly to the frame buffer 16 instead of the image buffer 15, the image buffer 15 can be omitted. In this case, the combining unit 14 is also unnecessary. However, the frame buffer 15
When there is a background or the like, the composition becomes difficult.

In the embodiment, in order to improve the memory efficiency,
Although the image buffer 15 for one line is prepared, any number of lines may be prepared. By combining several lines, the memory efficiency is degraded, but it is possible to write in the frame buffer as required, and high-speed processing becomes possible.

The external storage device 24 is not limited to a hard disk, but may be any storage device capable of storing stored data.
It can be replaced with another storage device such as M or a magneto-optical disk which can store digital information.

[0057]

As described above, according to the present invention, the number of inverting pixel segments in the corresponding pixel is obtained from the coordinate information of the intersection between the enlarged outline information and the scanning line, and based on this, The gray scale level of the pixel can be determined. Therefore, memory consumption can be reduced and high-speed processing can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of scan conversion.

FIG. 2 is a diagram illustrating an inverted state of a pixel segment in an example in which a start point and an end point of an edge list for a pixel segment are within the same pixel.

FIG. 3 is a diagram illustrating an inverted state of a pixel segment in an example in which a start point and an end point of an edge list for a pixel segment are in different pixels.

FIG. 4 is a diagram illustrating a state where edges are stored in a bitmap.

FIG. 5 is a diagram illustrating a state in which edges are stored in an edge list.

FIG. 6 is a diagram showing an example of a table prepared for calculating the number of inverted pixel segments.

FIG. 7 is a diagram illustrating an embodiment of the present invention.

FIG. 8 is a diagram illustrating a computer environment in which an embodiment of the present invention is realized.

FIG. 9 is a diagram (part 1) for explaining the operation of the embodiment of the present invention;

FIG. 10 is a diagram (part 2) for explaining the operation of the embodiment of the present invention;

FIG. 11 is a diagram illustrating a modification of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Input part 12 Scan conversion part 13 Gray scale preparation part 14 Synthesis part 15 Image buffer 16 Frame buffer

Claims (5)

[Claims] 1. A method for extracting coordinates of an intersection between a contour and a scanning line based on information on a contour to be drawn such as a character or a figure, and rendering a pixel between intersections satisfying a predetermined criterion. In the drawing apparatus, means for receiving the information on the contour line, generating information on the enlarged contour line by linearly transforming the coordinate values defining the contour, and finding an intersection between the enlarged contour line and the scanning line, A pixel value determining unit that calculates an ideal drawing processing area in the pixel based on the information of the intersection and determines a gray scale pixel value of the pixel based on the ideal drawing processing area in the pixel. A drawing apparatus, comprising: 2. The drawing processing apparatus according to claim 1, wherein an edge list generated by a scan conversion method is used as information of an intersection between the enlarged contour line and the scan line. 3. An image buffer means for storing the gray scale pixel value in one or a plurality of scanning lines, and a frame receiving the gray scale pixel value in the one or a plurality of scanning lines from the image buffer means. 2. The drawing apparatus according to claim 1, further comprising a buffer unit. 4. The drawing processing apparatus according to claim 1, wherein said pixel value determining means includes table means for outputting a gray scale pixel value of a corresponding pixel based on the information of said intersection. 5. Based on information on a contour line to be drawn such as a character or a figure, coordinates of an intersection point between the contour line and the scanning line are extracted, and a pixel between intersection points satisfying a predetermined criterion is drawn. A rendering device for performing a grayscale rendering process or a binary rendering process on the rendering device; and receiving the contour information when the grayscale rendering process is instructed, Means for generating information of an enlarged contour line by linearly transforming coordinate values defining the following.When a grayscale drawing process is instructed, an intersection between the enlarged contour line and the scanning line is obtained, and the intersection of the intersection is calculated. Calculate the ideal drawing processing area in the pixel based on the information,
A grayscale pixel value determining means for determining a grayscale pixel value of the pixel based on an ideal drawing processing area within the pixel; and when a grayscale drawing process is instructed, the grayscale pixel value is changed to Image buffer means for storing one or a plurality of scanning lines; and when a binary drawing process is instructed, information on the contour line to be drawn is received, and an intersection between the contour line and the scanning line is obtained. A binary pixel determining means for determining a binary pixel value based on the information of the intersection; and receiving the gray scale pixel value from the image buffer means when the gray scale drawing processing is instructed, the binary drawing processing And frame buffer means for receiving the binary pixel value from the binary pixel value determining means when is designated. Drawing device.