JP2005128173A - Figure drawing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a figure drawing apparatus which avoids problems in a picture quality when drawing a straight line and a dot. <P>SOLUTION: In the figure drawing apparatus 100 for drawing a figure in a display, a number of pixels are arranged in the display and each pixel is composed of tentatively determined sequential arrangement of sub-pixel of each color in three primary colors and the coordinate apparatus in which the sub-pixel is a unit coordinate is constituted in the display. The figure drawing apparatus 100 tentatively determines the sub-pixel to be light emitted from a vertex coordinate of an inputted figure and determines whether the tentatively determined sub-pixel is a prescribed 1 reference color or not. If the determination is positive, the tentatively determined sub-pixel is determined to be the sub-pixel to be light emitted and if the determination is negative, the sub-pixel which is the same emitting color with the reference color in the pixel to which the tentatively determined sub-pixel belongs or in an adjacent pixel is determined to be the sub-pixel to be light emitted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a graphic drawing apparatus that draws a graphic by individually controlling each subpixel that emits R, G, and B3 primary colors, and more particularly to a technique for improving the image quality of a graphic displayed in the graphic drawing apparatus.

A display screen of a display (for example, a liquid crystal display or a plasma display) used in a conventional graphic drawing apparatus is formed by repeatedly arranging light emitting elements of R, G, and B3 primary colors in this order in one direction.
Here, each light emitting element is called a sub pixel, and one pixel (one pixel) is constituted by three sub pixels of R, G, and B.

Usually, the display is performed in units of one pixel. However, in a mobile terminal such as a mobile phone, the area of a display that can be mounted is small, and if a character or a figure is to be displayed in a small size, shaggy is likely to occur in a diagonal line due to low resolution.
As a countermeasure technique, Patent Document 1 discloses a technique for improving visibility compared with simple pixel-by-pixel display by individually controlling R, G, and B sub-pixels arranged on the display screen of the display. Has been.

Hereinafter, the technique disclosed in the above patent document will be described with reference to FIGS. Hereinafter, a case where an English letter “A” is drawn on the display screen will be taken as an example.
FIG. 6 is a diagram showing a repetitive arrangement formed by three R, G, and B sub-pixels constituting one pixel on the display screen. The horizontal direction (arrangement direction of three RGB subpixels) in FIG. 6 is referred to as a first direction, and the vertical direction orthogonal to the horizontal direction is referred to as a second direction. On the display screen, a plurality of repetitive arrays of the R, G, and B subpixels are arranged in the second direction shown in FIG.

Note that the arrangement order of the three sub-pixels may be other arrangement orders other than the RGB order.
FIG. 7 shows an example of display on the display screen when the English letter “A” is drawn in units of pixels. In this example, the letter “A” is displayed in an area of 7 pixels vertically and horizontally.

On the other hand, FIG. 8 shows an example of display on the display screen when the above-mentioned English characters are drawn in sub-pixel units. In the display of FIG. 8, each subpixel of RGB is regarded as one pixel, and the character “A” is displayed in an area having 21 (= 7 × 3) subpixels in the horizontal direction and 7 pixels in the vertical direction. ing.
However, if display is performed as it is, color unevenness occurs, and therefore, filtering processing using coefficients as shown in FIG. 9 is performed on each subpixel arranged on the display screen. FIG. 9 shows a coefficient for luminance. The center target subpixel to be processed is 3/9 times, the adjacent subpixel is 2/9 times, and the adjacent subpixel is 1/9 times. The luminance of the sub-pixel to be processed is adjusted by multiplying the coefficient such as 9 times.

In this way, by filtering and displaying characters drawn in units of sub-pixels, shaggy shading is not noticeable, and high-quality display can be realized.
The above-described prior art enables higher-definition character drawing by triple the drawing accuracy in the first direction compared to pixel-by-pixel drawing. This prior art can also be applied to general graphics drawing (straight lines, polygons, etc.).

For example, when drawing is performed in units of pixels, drawing of hatched lines displayed on the display screen as shown in FIG. 10A is also drawn in units of subpixels, and is appropriately filtered to perform shaggy as shown in FIG. 10B. It is possible to display a hatched drawing without a mark on the display screen.
Japanese Patent Application 2002-011851

However, the following problems occur when a straight line or a point parallel to the second direction as shown in FIGS. 11A, 11B, and 11C is drawn using the above-described conventional technique.
For example, when a straight line is drawn in units of pixels, it is normal to have an array with G (green) emitting sub-pixels at the center as shown in FIG. Since the drawing positions of the vertices at both ends of the straight line are determined in units of subpixels, and the subpixels for drawing the interpolation line that interpolates between the vertices are determined based on the determined drawing positions of the vertices, As shown in FIGS. 11A and 11C, the arrangement order of R, G, and B subpixels for drawing a straight line may be different.

  Specifically, when the drawing position determined for each vertex at both ends of the straight line is on a sub-pixel that emits B (blue), an interpolation straight line obtained by extending the drawing width by two sub-pixels in a predetermined direction is As shown in FIG. 11A, when the drawing positions determined for the vertices at both ends of the straight line are on sub-pixels that emit R (red), the drawing width is set to the amount of two sub-pixels in a predetermined direction. The extended interpolation straight line is as shown in FIG. 11B, and when the drawing position determined for each vertex of the straight line is on a sub-pixel emitting G (green), the drawing width is set to a predetermined direction. The interpolation straight line extended by two subpixels is as shown in FIG.

As described above, when the arrangement order of R, G, and B sub-pixels for drawing each interpolation line is different, if each interpolation line is drawn continuously in the macro range of the display screen, drawing is performed in units of pixels. As compared with the case where it is applied, there arises a problem that a difference in visual coloring (weakening of coloring or deviation from the original color) is easily recognized.
The present invention has been made in view of the above problems, and in general graphics drawing, when drawing straight lines and points, an array of R, G, and B sub-pixels that draw straight lines and points. It is an object of the present invention to provide a graphic drawing apparatus that avoids problems in image quality caused by different orders.

  In order to solve the above-mentioned problems, the present invention is a figure drawing apparatus for inputting a vertex coordinate of a figure to be drawn and drawing the figure on a display, and a plurality of pixels are arranged on the display screen of the display. Each pixel is composed of an array of sub-pixels of each of the three primary colors in a predetermined order, and the display screen constitutes a coordinate system having sub-pixels as unit coordinates. Receiving means for receiving the coordinates of the vertexes, temporarily determining means for temporarily determining the subpixels to be lit based on the received numerical values of the vertex coordinates, and the temporarily determined subpixels are a predetermined reference color. A determination means for determining whether or not, and if the determination is affirmative, the tentatively determined subpixel is determined as a subpixel to be emitted, and if the determination is negative, the tentatively determined subpixel is determined Kuseru is in belongs pixels or in the vicinity pixel, and a determination means for performing determination processing for determining the sub-pixels to be lit subpixel of the same luminescent color and the reference color.

Since the present invention is provided with the above-described configuration, the sub-pixel for drawing the vertex is controlled to always be a sub-pixel for emitting a predetermined reference color among the three primary colors, so that a straight line or a point is drawn. It is possible to avoid image quality problems caused by the arrangement order of the R, G, and B subpixels being different.
In this case, when the determination is negative, the determination means uses the same emission color as the reference color among the subpixels adjacent to the determined subpixel in the arrangement direction of the subpixels of each color. A certain subpixel may be determined as a subpixel to emit light.

  As a result, sub-pixels that emit a predetermined reference color are selected from sub-pixels adjacent to the position of the first selected sub-pixel, so that the position of each vertex coordinate is almost from the position intended at the time of input. Without moving, it is possible to avoid image quality problems caused by different arrangement orders of R, G, and B sub-pixels that draw straight lines and points.

Here, the receiving means may receive an input of the type of graphic to be drawn, and the determining means may perform the determining process only when the received graphic type is a straight line or a point.
As a result, the sub-pixel determination process can be executed only when the figure to be drawn is a point or straight line that is likely to cause image quality problems due to the arrangement order of the R, G, and B sub-pixels. Therefore, it is possible to avoid image quality problems caused by different arrangement orders of the R, G, and B sub-pixels for drawing a straight line or a point without performing unnecessary processing.

Here, when the received graphic type is a straight line, the determining means calculates a straight line slope absolute value based on each vertex coordinate of the received straight line, and the calculated slope absolute value is Inclination determining means for determining whether or not the predetermined value is larger than a predetermined threshold, and the determining means may perform the determining process only when the absolute value is larger than the predetermined threshold.
As a result, the sub-pixel determination process is executed only for a straight line in a direction (for example, the vertical direction) in which a visual color difference is easily recognized with respect to the arrangement direction of the R, G, and B sub-pixels. Therefore, it is possible to efficiently avoid the image quality problem caused by the arrangement order of the R, G, and B sub-pixels being different.

A graphic drawing apparatus according to an embodiment of the present invention is a graphic drawing apparatus that draws a graphic by individually controlling each of R, G, and B sub-pixels constituting one pixel in a display of the graphic drawing apparatus. Then, by finely adjusting the determined vertex coordinates of the vertices of the graphic drawn on the display screen of the display so that the types of the light emitting elements of the subpixels corresponding to the vertex coordinates match, R, G , B is a graphic drawing apparatus capable of avoiding the problem of image quality caused by drawing a straight line or a point in which the order of arrangement of the sub-pixels is different in a macro.
<Configuration>
FIG. 1 is a functional block diagram showing an overall configuration of a graphic drawing apparatus 100 according to an embodiment of the present invention. The graphic drawing apparatus 100 includes a processor unit 101, a drawing processing unit 102, a work memory 103, and a display device 104.

The graphic drawing apparatus 100 includes a CPU, a ROM, a RAM, a hard disk, an input device, a liquid crystal display, and the like as hardware. A computer program is stored in the ROM or the hard disk, and the CPU operates according to the computer program. Thus, the device achieves its function.
The processor unit 101 includes a drawing figure determination unit 1011, a vertex coordinate scale unit 1012, and a vertex coordinate modification unit 1013.

  The drawing figure determination unit 101 specifies the type of figure to be drawn from the user via an input device or the like (not shown) and each vertex (both ends of a straight line when the figure to be drawn is a straight line) or each vertex. (For example, apex at both ends of the diagonal line when the figure type is “Rectangle”, the center position of the rectangle and the distance from the center position to each side) is received, and drawing is performed based on the received specification. Each vertex coordinate that identifies a figure is identified, and each identified vertex coordinate is projected onto a two-dimensional space while being subjected to geometric processing such as coordinate transformation, field transformation, and hidden surface removal, and displayed on the display screen of the display device 104 The vertex coordinates of the figure to be determined are determined, and the determined vertex coordinates and the designated figure type are output to the vertex coordinate scale unit 1012.

Thereby, each designated vertex coordinate is arranged in the first direction and the second direction shown in FIG. 6 on the display screen of the display device 104, and is composed of R, G, and B subpixels. It is converted into coordinates associated with the position of each pixel and output.
Here, the designated “type of figure” includes, for example, a polygon, a straight line, a point, and the like in the case of a processing system of a general 3D graphics function.

Further, the determined vertex coordinates may be coordinates represented by integer coordinates assigned in pixel units, or may be coordinates represented in a form such as a floating point with higher accuracy. Further, it is possible to determine a color (for example, RGB value) for each vertex, and this information is used when coloring a polygon or the like in the drawing processing unit 102 described later.
The vertex coordinate scale unit 1012 uses the respective vertex coordinates (here, (x, y), the first direction is the x axis, and the second direction is the y axis) input from the drawing figure determining unit 101. In order to process with triple precision in the first direction, the process of converting the vertex coordinates (x, y) is performed, and the coordinates after processing (here, (x ′, y ′)) are designated. The figure type is output to the vertex coordinate modification unit 1013.

Specifically, the vertex coordinate scale unit 1012 performs the following coordinate conversion processing.
The vertex coordinate scale unit 1012 calculates the vertex coordinates (x ′, y ′) after the coordinate conversion processing by the following formula (Formula 1).
(Formula 1)
x ′ = {3x}, y ′ = {y}
Here, {3x} represents an integer value closest to the value indicated by “3x”, and {y} represents an integer value closest to the value indicated by “y”. For example, in the case of “x = 1.2”, “3x = 3.6” and “{3x} = 4”.

With this coordinate conversion process, each vertex coordinate after the coordinate conversion process is displayed on the display of the display device 104 in which a plurality of repetitive arrays of R, G, and B subpixels are arranged in the second direction as shown in FIG. On the display screen, it is converted into coordinates associated with the position of each sub-pixel and output.
The vertex coordinate modification unit 1013 performs vertex coordinate modification processing according to the type of figure input from the vertex coordinate scale unit 1012.

Specifically, when the type of figure is a straight line or a point, x ′, which is the x coordinate of the input vertex coordinate, is corrected to a multiple of 3 that is the closest to it, and the corrected coordinate is rendered as a drawing processing unit. If the figure type is other than the above, x ′ is output to the drawing processing unit 102 without modification.
The drawing processing unit 102 includes a DDA setup unit 1021, a DDA unit 1022, a first direction extension unit 1023, and a filtering unit 1024.

The DDA setup unit 1021 calculates gradient parameters related to the polygon shape, drawing color, and the like based on the input vertex coordinates and the like, and outputs them to the DDA unit 1022.
Based on the gradient parameter input from the DDA setup unit 1021, the DDA unit 1022 uses a linear interpolation method called DDA (Digital Differential Analyze) to determine the interior of polygons constituting the foreground image and between vertex coordinates. Each subpixel for drawing a straight line to be interpolated (hereinafter referred to as “interpolated straight line”) is determined, and for each determined subpixel (hereinafter referred to as “drawing subpixel”) and for each subpixel constituting the background image. The color information indicated by the RGB values and the α value are determined, and the color information of the foreground image and the background image is translucently synthesized.

  Here, the α value refers to a value indicating the transmittance of the foreground image when the foreground image and the background image are translucently combined, and takes a value from 0 to 1. When the α value is 0, the foreground image becomes transparent, and the color information of the background image becomes the color information after the semi-transparent composition. When the α value is 1, the foreground image becomes opaque and the foreground image Is the color information after the semi-transparent composition, and when the α value is 0 <α <1, the weighted average of the color information of the foreground image and the color information of the background image becomes the color information after the composition. .

Specifically, for each subpixel, color information in the foreground image is Rp (x ′, y ′), Gp (x ′, y ′), Bp (x ′, y ′), and α value in the foreground image is α. If the color information in the background image is Rb (x ′, y ′), Gb (x ′, y ′), and Bb (x ′, y ′), the color information after translucent synthesis Ra (x ′, y ′), Ga (x ′, y ′), and Ba (x ′, y ′) are calculated by the following calculation formulas (Formula 2 to Formula 4).
(Formula 2)
Ra (x ′, y ′) = Rp (x ′, y ′) × α (x ′, y ′) + Rb (x ′, y ′) × (1−α (x ′, y ′))
(Formula 3)
Ga (x ′, y ′) = Gp (x ′, y ′) × α (x ′, y ′) + Gb (x ′, y ′) × (1−α (x ′, y ′))
(Formula 4)
Ba (x ′, y ′) = Bp (x ′, y ′) × α (x ′, y ′) + Bb (x ′, y ′) × (1−α (x ′, y ′))
The first direction extension unit 1023 performs processing for extending the vertex coordinates constituting the foreground screen and the drawing width of the interpolation line connecting them.

  Specifically, a subpixel adjacent in the first direction of the drawing subpixel (hereinafter referred to as “first adjacent subpixel”), a subpixel adjacent in the first direction of the first adjacent subpixel (hereinafter referred to as “first adjacent subpixel”). The color information of the first and second adjacent subpixels of each drawing subpixel and the α value so that each RGB value of “second subpixel” is the same value as the RGB value of the drawing subpixel. And color information of the foreground image and the background image is translucently synthesized.

FIG. 3A shows a specific example when an interpolation line is drawn on the display device 104 based on the color information of each drawing sub-pixel that is semitransparently synthesized by the DDA unit 1022.
FIG. 3B illustrates an interpolation line displayed on the display device 104 based on the color information of the drawing subpixel and the first and second adjacent subpixels translucently synthesized by the DDA unit 1022 and the first direction extension unit 1023, respectively. A specific example when drawing is shown.

A filtering unit 1024 reduces the figure to be drawn to 1/3 and eliminates color unevenness based on each vertex coordinate expanded three times in the first direction by the vertex coordinate scale unit 1012. Perform luminance filtering.
FIG. 2 is a functional block diagram illustrating the configuration of the filtering unit 1024.
The filtering unit 1024 includes a color space conversion unit 10241, a luminance filtering unit 10242, a filtering coefficient storage unit 10243, a color difference filtering unit 10244, and an RGB mapping unit 10245.

The color space conversion unit 10241 performs color space conversion (YCbCr conversion) on the color information of each sub-pixel synthesized by the DDA unit 1022 and the first direction extension unit 1023. Specifically, it is performed by the following mathematical formulas 5-7.
(Formula 5)
Y (x ′, y ′) = 0.299 × Ra (x ′, y ′) + 0.587 × Ga (x ′, y ′) + 0.114 × Ba (x ′, y ′)
(Formula 6)
Cb (x ′, y ′) = − 0.1687 × Ra (x ′, y ′) − 0.3313 × Ga (x ′, y ′) + 0.5 × Ba (x ′, y ′)
(Formula 7)
Cr (x ′, y ′) = 0.5 × Ra (x ′, y ′) − 0.4187 × Ga (x ′, y ′) + 0.0813 × Ba (x ′, y ′)
Here, Y (x ′, y ′) is the luminance in the sub-pixel to be processed (hereinafter referred to as “target sub-pixel”), Cb (x ′, y ′) is the blue difference in the target sub-pixel, Cr (X ′, y ′) represents the red color difference in the target sub-pixel.

The luminance filtering unit 10242 performs a luminance filtering process on Y (x ′, y ′) subjected to color space conversion using the filtering coefficient stored in the filtering coefficient storage unit 10243.
Specifically, the luminance filtering process for the target sub-pixel is performed using Expression 8 shown below.
(Formula 8)
Yoi = C1 * Yi-2 + C2 * Yi-1 + C3 * Yi + C4 * Yi + 1 + C5 * Yi + 2
Here, Yoi represents the luminance in the target sub-pixel after the filtering process, and “i”, “i−1”, and “i + 1” are coordinates C, (x′−1, y ′), (x '+1, y'), and C1, C2, C3, C4, and C5 represent the respective filtering coefficients stored in the filtering coefficient storage unit 10243. As the filtering coefficient, for example, C1 = 1/9, C2 = 2/9, C3 = 3/9, C4 = 2/9, and C5 = 1/9 can be used.

The filtering coefficient storage unit 10243 stores C1, C2, C3, C4, and C5 filtering coefficients.
The color difference filtering unit 10244 performs a color difference filtering process on Cb (x ′, y ′) and Cr (x ′, y ′) subjected to color space conversion. Specifically, the color difference in units of sub-pixels in the target sub-pixel is converted into the color difference in units of pixels using Equations 9 to 11 shown below.
(Formula 9)
Cb_ave (x ′, y ′) = (Cb (x ′ = 3x, y ′ = y) + Cb (x ′ = 3x + 1, y ′ = y) + Cb (x ′ = 3x + 2, y ′ = y)) / 3
(Formula 10)
Cr_ave (x ′, y ′) = (Cr (x ′ = 3x, y ′ = y) + Cr (x ′ = 3x + 1, y ′ = y) + Cr (x ′ = 3x + 2, y ′ = y)) / 3
Here, Cb_ave (x ′, y ′) and Cr_ave (x ′, y ′) represent the blue color difference and the red color difference of the subpixel of interest after the filtering process, respectively.

The RGB mapping unit 10245 inversely converts the luminance and color difference in each target sub-pixel after being filtered by the luminance filtering unit 10242 and the color difference filtering unit 10244 into color information, and the inversely converted color information is stored in the work memory 103. Record.
Specifically, the RGB mapping unit 10245 performs a reverse conversion process using Equations 11 to 13 shown below.
(Formula 11)
R (x ′, y ′) = Y (x ′ = 3x, y ′) − 1.402 × Cr_ave (x ′, y ′)
(Formula 12)
G (x ′, y ′) = Y (x ′ = 3x + 1, y ′) − 0.34414 × Cb_ave (x ′, y ′) − 0.71414 × Cr_ave (3x ′ + 2, y ′)
(Formula 13)
B (x ′, y ′) = Y (x ′ = 3x + 2, y ′) + 1.772 × Cr_ave (x ′, y ′)
The work memory 103 stores color information of each subpixel of interest that has been inversely transformed.

The display device 104 includes a display, and draws a designated figure on the display based on each color information stored in the work memory 103.
<Operation>
Next, the operation of the vertex coordinate correction process performed by the vertex coordinate correction unit 1013 will be described. FIG. 4 is a flowchart showing the above operation. The above operation will be described below with reference to FIG.

When the vertex coordinate correcting unit 1013 receives the specified figure type and each vertex coordinate after the conversion process from the vertex coordinate scale unit 1012 (step S401), the specified vertex type is either a point or a straight line. It is determined whether or not there is any (step S402).
When the specified figure type is either a point or a straight line (step S402: Y), for each vertex coordinate, the x coordinate (x ′) is a multiple of 3 (3n: n is a variable indicating an integer value) It is determined whether it is “3n + 1” or “3n + 2” (step S403).

If “x ′ = 3n + 1”, the x-coordinate of the vertex coordinate point is corrected to “x ′ = 3n” (step S404), and the process proceeds to step S406.
If “x ′ = 3n”, the process proceeds to step S406 without correcting the x coordinate of the vertex coordinate point.
If “x ′ = 3n + 2”, it is corrected to “x ′ = 3 (n + 1)” (step S405), and the process proceeds to step S406.

In step S402, when the designated graphic is neither a point nor a straight line (step S402: N), the process proceeds to step S406.
In step S406, the vertex coordinate modification unit 1013 outputs the vertex coordinates processed in steps S402, S403, S404, and S405 to the drawing processing unit 102 (step S406).

  FIG. 12 is an image diagram showing a state in which the subpixels for drawing the vertex coordinates are corrected to the adjacent subpixels in the operation of the vertex coordinate correction process of FIG. 1201 in FIG. 12 indicates a sub-pixel that emits R (red) whose x coordinate is associated with a vertex coordinate of 3n, and 1202 is G (green) associated with a vertex coordinate whose x coordinate is 3n + 1. Indicates a sub-pixel that emits B (blue) corresponding to the vertex coordinate of 3n + 2 and 1204 indicates the vertex coordinate of 3 (n + 1). A subpixel that emits light corresponding to R (red) is shown.

  As indicated by an arrow in FIG. 12, in the operation of the vertex coordinate correction process in FIG. 4, when it is determined that the x coordinate of the vertex coordinate is 3n + 1, the subpixel that emits the vertex coordinate is 1202 sub-pixels. If the pixel is corrected to 1201 subpixel and the x coordinate of the vertex coordinate point is determined to be 3n + 2, the subpixel that develops the coordinate point is corrected from 1203 subpixel to 1204 subpixel. When it is determined that the x coordinate of the vertex coordinates is 3n, the sub-pixel that emits the vertex coordinates remains 1201 and is not corrected.

Thereby, each vertex coordinate can be controlled to be emitted by the sub-pixel emitting R (red).
<Supplement>
As mentioned above, although demonstrated based on embodiment of the figure drawing apparatus concerning this invention, of course, this invention is not limited to these embodiment.

  (1) In the present embodiment, in the operation of the vertex coordinate correction process shown in FIG. 4, the vertex coordinate correction unit 1013 determines that the designated graphic is either a point or a straight line (step S402: Y). The x coordinate of the vertex coordinate is corrected, but when the type of the specified figure is a straight line, it is further determined whether the absolute value of the slope of the straight line is larger than a preset threshold value. In this case, the processing in steps S403 to S405 in FIG. 4 may be performed.

FIG. 5 is a flowchart showing the operation of a modified example of the vertex coordinate correction process described above. As shown in FIG. 5, the same step number as that of FIG. 4 is assigned to the same process as the vertex coordinate correction process shown in FIG. 4, and different step numbers are assigned to different processes.
Hereinafter, the description of the same processing as that in FIG.
If the determination in step S402 is affirmative (step S402: Y), the vertex coordinate correcting unit 1013 determines whether or not the type of the specified figure is a straight line (step S502), and if the straight line is a straight line (step S502) Step S502: Y) Based on the received vertex coordinates, the absolute value of the slope of the straight line is calculated, and it is determined whether or not the calculated absolute value is larger than a preset threshold value (Step S503). Step S503: Y), the process proceeds to step S403. In step S502, when the type of the designated figure is not a straight line (step S502: N), the vertex coordinate correction unit 1013 proceeds to the process of step S403, and in step S503, the calculated absolute value is greater than a preset threshold value. If not large (step S503: N), the process proceeds to step S406.

  (2) In this embodiment, when the figure type is a straight line or a point, the vertex coordinate modification unit 1013 sets x ′, which is the x coordinate of the input vertex coordinate, to a multiple of 3 that is closest to it. However, the value of x ′ after the correction may be determined so that the vertex coordinates are always associated with one of R, G, and B subpixels. For example, the value may be a value obtained by adding 1 to a multiple of 3, or a value obtained by adding 2 to a multiple of 3.

  (3) In the present embodiment, the first direction extension unit 1023 extends the drawing width of the interpolation straight line by two subpixels (first and second adjacent subpixels) in the first direction. However, the direction in which the drawing width is extended is not limited to the first direction. For example, the drawing width may be extended by one subpixel on both sides of the interpolation line. FIG. 3C shows a specific example when the extended interpolation straight line in the above case is drawn on the display device 104.

Further, instead of extending the drawing width, for example, in the vertex coordinate scale unit 1012, the x coordinate of the vertex coordinate input from the drawing figure determining unit 101 is tripled, and at the same time, the drawing figure is moved from the straight line to the first direction by 2 It is good also as changing to the square which lengthened the sub pixel (for example, two polygons).
Further, the drawing width extension processing by the first direction extension unit 1023 is not limited to the case of drawing a straight line, and may be performed in the same manner as in the case of a straight line when drawing a polygon or a point.

  (4) In the present embodiment, filtering coefficients C1 = 1/9, C2 = 2/9, C3 = 3/9, C4 = 2/9, and C5 = 1/9 are used for the luminance filtering process. The filtering coefficients are not limited to the above values, and other coefficients may be used.

  INDUSTRIAL APPLICABILITY The present invention can be used as a technique for improving the image quality of a displayed graphic in a graphic drawing apparatus that draws a graphic by individually controlling R, G, and B subpixels.

It is a functional block diagram which shows the whole structure of the graphics drawing apparatus 100 which concerns on embodiment of this invention. 3 is a functional block diagram illustrating a configuration of a filtering unit 1024. FIG. A specific example in the case where an interpolation line is drawn on the display device 104 before and after the drawing width is extended by the first direction extension unit 1023 will be described. It is a flowchart which shows the operation | movement of the vertex coordinate correction process which the vertex coordinate correction part 1013 performs. It is a flowchart which shows operation | movement of the modification of a vertex coordinate correction process. It is a figure which shows the repeating arrangement | sequence which three R, G, B sub-pixels which comprise 1 pixel form. An example of display on the display screen when an English letter “A” is drawn in units of pixels is shown. An example of display on the display screen when an English letter “A” is drawn in sub-pixel units is shown. It is an image figure which shows the relationship between the coefficient with respect to the position of a sub pixel, and a brightness | luminance. Specific examples of drawing displayed on the display screen when the hatched drawing is performed in units of pixels and in the case of being performed in units of subpixels will be shown. A specific example of a drawn straight line when a straight line parallel to the second direction is drawn in sub-pixel units will be described. FIG. 5 is an image diagram showing a state in which a sub-pixel for drawing a vertex coordinate is corrected to an adjacent sub-pixel in the operation of the vertex coordinate correction process of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Graphic drawing apparatus 101 Processor part 102 Drawing process part 103 Work memory 104 Display device 1011 Drawing figure determination part 1012 Vertex coordinate scale part 1013 Vertex coordinate correction part 1021 DDA setup part 1022 DDA part 1023 1st direction expansion part 1024 Filtering part 10241 Color space conversion unit 10242 Luminance filtering unit 10243 Filtering coefficient storage unit 10244 Color difference filtering unit 10245 RGB mapping unit

Claims (4)

A figure drawing device for inputting vertex coordinates of a figure to be drawn and drawing the figure on a display,
A number of pixels are arranged on the display screen of the display, and each pixel includes an arrangement in a predetermined order of sub-pixels of each of the three primary colors,
The display screen constitutes a coordinate system having sub-pixels as unit coordinates,
The graphic drawing device
A receiving means for receiving an input of vertex coordinates of a figure to be drawn;
Temporary determination means for temporarily determining the subpixels to be lit from the received vertex coordinate values;
Determination means for determining whether or not the temporarily determined subpixel is a predetermined reference color;
If the determination is affirmative, the tentatively determined subpixel is determined as a subpixel to be emitted,
When the determination is negative, a decision is made to perform a decision process for deciding that a sub-pixel having the same emission color as the reference color in a pixel to which the tentative sub-pixel belongs or a pixel in the vicinity thereof is a sub-pixel to be emitted. Means,
A graphic drawing apparatus comprising: When the determination is negative, the determining means is a subpixel having the same emission color as the reference color among the subpixels adjacent to the determined subpixel in the arrangement direction of the subpixels of each color. The figure drawing apparatus according to claim 1, wherein the sub-pixel to be emitted is determined. The receiving means receives an input of the type of figure to be drawn,
3. The graphic drawing apparatus according to claim 2, wherein the determination unit performs the determination process only when the type of the received graphic is a straight line or a point. The determining means includes
A calculation means for calculating the absolute value of the inclination of the straight line based on each vertex coordinate of the received straight line when the type of the received graphic is a straight line;
Inclination determination means for determining whether or not the absolute value of the calculated inclination is larger than a predetermined threshold;
The graphic drawing apparatus according to claim 3, wherein the determination unit performs the determination process only when the absolute value is larger than a predetermined threshold value.

Images