JP5747553B2 - Image processing system and program - Google Patents

Description

  The present invention relates to an image processing system and a program.

  Japanese Patent Application Laid-Open No. 2005-228561 describes a method of generating in advance an image in which a dither matrix area is filled with a gradation value as a gradation value pattern image.

JP 2001-128015 A

  An object of the present invention is to reduce the processing load in the case of drawing a binary image obtained by performing dither processing on an image including a region where the gradation changes according to the position in the main scanning direction.

The invention according to claim 1 for solving the above-described problem is a drawing means for drawing a dither image obtained by binarizing an output target image with a dither matrix on a storage means based on image information described in a page description language. includes, and output means for outputting a dither image drawn on said storage means, said drawing means is parallel to the main scanning direction, and, the main scanning direction perpendicular to the sub-scanning direction width of said Based on the image information, the output target is the presence of a rectangular gradation area that is larger than a reference distance that is a width in the sub-scanning direction of the dither matrix and whose gradation changes according to the position in the main scanning direction. Detecting means for detecting the image area corresponding to the image of the image, and a rectangular shape of a part of the gradation area when the detecting means detects the presence of the gradation area Generating means for generating a dither image of an area, a partial area in which the width in the sub-scanning direction is the reference distance and the width in the main scanning direction is the same as the gradation area; A gradation rendering unit that renders the dither image of the gradation area in the storage unit based on the generated dither image.

  According to a second aspect of the present invention, in the first aspect of the invention, the first threshold included in the dither matrix and the reference distance in the sub-scanning direction from the first threshold included in the dither matrix. The second threshold value at the same position is the same.

According to a third aspect of the present invention for solving the above-described problem, a drawing is performed in which a dither image obtained by binarizing an output target image with a dither matrix is drawn in a storage unit based on image information described in a page description language. And a computer functioning as output means for outputting a dither image drawn in the storage means, wherein the drawing means is parallel to the main scanning direction and perpendicular to the main scanning direction. Is based on the image information, the presence of a rectangular gradation region that is larger than a reference distance that is the width in the sub-scanning direction of the dither matrix and whose gradation changes according to the position in the main scanning direction. Detecting means for detecting an image area corresponding to the image to be output; and when the detecting means detects the presence of the gradation area, the gradation area is detected. A dither image of a part of the rectangular region, wherein the width in the sub-scanning direction is the reference distance and the width in the main scanning direction is the same as the gradation region And a gradation drawing means for drawing the dither image of the gradation area in the storage means based on the dither image generated by the generating means.

  According to the first and third aspects of the present invention, the processing load can be reduced when a binary image obtained by performing dither processing on an image including an area that changes in gradation according to the position in the main scanning direction is drawn. Can be planned.

  According to the second aspect of the present invention, when a binary image obtained by performing dither processing on an image including a region where the gradation changes according to the position in the main scanning direction is rendered as compared with the case where the present configuration is not provided. The processing load can be reduced more reliably.

1 is a diagram illustrating a configuration of an image processing system. It is a figure for demonstrating PDL data. It is a figure for demonstrating PDL data. It is a figure which illustrates the interpretation result of a drawing command. It is a figure which illustrates a page buffer area. It is a figure which illustrates a dither matrix. It is a figure which illustrates a unit threshold value matrix. It is a flowchart which illustrates the process which a control part performs. It is a flowchart which illustrates the process which a control part performs. It is a flowchart which illustrates the process which a control part performs. It is a figure which illustrates an attention area. It is a figure which shows notionally drawing of the dither image of a gradation area | region. It is a flowchart which illustrates the process which a control part performs. It is a flowchart which illustrates the process which a control part performs.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

[Image processing system]
FIG. 1 is a diagram illustrating the configuration of an image processing system according to the present invention. In the case of this embodiment, the image processing system is realized as the page printer 2 including the control unit 4, the storage unit 6, and the image forming unit 8.

  The control unit 4 is, for example, a microprocessor, and executes image processing according to an image processing program stored in the storage unit 6.

  The storage unit 6 includes a RAM and a ROM, and the storage unit 6 stores data necessary for the process of the image processing by the control unit 4. The storage unit 6 (specifically, ROM) stores the image processing program. The image processing program may be read from a computer-readable information storage medium such as a DVD (registered trademark) -ROM and stored in the storage unit 6, or supplied from a communication network such as a network and stored in the storage unit 6. May be stored.

  As shown in the figure, PDL data (image information) described in a page description language is input to the page printer 2. The PDL data indicates a page image to be output. In this page printer 2, when PDL data is input, a dither image obtained by performing dither processing on the page image represented by the PDL data is printed on a printing paper. Specifically, the control unit 4 (rendering unit) renders a dither image obtained by performing dither processing on the page image on the page buffer area (image area) of the storage unit 6 based on the PDL data, and serves as a printer engine. The realized image forming unit 8 (output unit) prints (outputs) the dither image drawn in the page buffer area in accordance with an instruction from the control unit 4.

[PDL data]
2 and 3 are diagrams for explaining the PDL data. The PDL data includes a plurality of drawing commands, and a page image is expressed as an image on a so-called current page plane by these drawing commands. FIG. 3 illustrates the description content of the PDL data. FIG. 2 illustrates a page image represented by the PDL data shown in FIG. As shown in FIG. 2, in the current page plane 10, an α axis and a β axis perpendicular to the α axis are set as coordinate axes.

  As shown in FIG. 3, the PDL data includes a plurality of drawing commands. A character string (for example, “0.98 setgray 10 10 800 100 rectfill”) written in one horizontal row indicates one drawing command.

  Each drawing command includes an area on the current page plane to be drawn (hereinafter referred to as a virtual drawing target area) and a virtual gradation (hereinafter referred to as virtual gradation) of the virtual drawing target area. ). For example, in the virtual drawing target area A1 indicated by the top drawing command, the coordinate value (α, β) of the lower left vertex is (10, 10), and the width (length) in the α axis direction is “800”. ”And a rectangular area whose width (height) in the β-axis direction is“ 150 ”, and the virtual gradation indicated by this drawing command is“ 0.98 ”(see FIG. 2). Also, for example, the virtual drawing target area A2 indicated by the second drawing command from the top has a coordinate value of the lower left vertex of (10, 160), a length of “800”, and a height of “150”. This is a rectangular area, and the virtual gradation indicated by this drawing command is “0.78” (see FIG. 2). Further, for example, the virtual drawing target area A3 indicated by the third drawing command from the top has the coordinate value of the lower left vertex (10, 310), the length “800”, and the height “150”. This is a rectangular area, and the virtual gradation indicated by this drawing command is “0.58” (see FIG. 2). For example, the virtual drawing target area A4 indicated by the fourth drawing command from the top has a coordinate value of the lower left vertex of (10, 460), a length of “800”, and a height of “150”. This is a rectangular area, and the virtual gradation indicated by this drawing command is “0.38” (see FIG. 2). Also, for example, the virtual drawing target area A5 indicated by the bottom drawing command is a rectangle whose bottom left vertex has a coordinate value of (300, 300), a length of “200”, and a height of “100”. The virtual gradation indicated by this drawing command is “01.00” (see FIG. 2).

  Here, the virtual gradation “0.00” indicates the maximum gradation, and the virtual gradation “1.00” indicates the minimum gradation. Therefore, as illustrated in FIG. 2, the virtual drawing target area A1, the virtual drawing target area A2, the virtual drawing target area A3, and the virtual drawing target area A4 are darkened in order. The virtual drawing target area A5 is filled with white.

  Hereinafter, a drawing command including the character string “rectfill” is referred to as a rectangular drawing command. In FIG. 3, only the rectangle drawing command is shown, but of course, the PDL data may include drawing commands other than the rectangle drawing command.

  In the page printer 2, one of a so-called SEF (Short Edge Feed) method and a LEF (Long Edge Feed) method is selected as the output format of the dither image. In the page printer 2, each drawing command is sequentially interpreted according to the selected output format, and an area in the page buffer area corresponding to the virtual drawing target area (hereinafter referred to as a drawing target area). Is identified. Further, for example, when the drawing command is a rectangular drawing command, the gradation value corresponding to the virtual gradation is specified.

  FIG. 4 illustrates the interpretation result of the drawing command shown in FIG. The Nth (N = 1 to 5) th interpretation result from the top indicates the interpretation result of the Nth drawing command from the top. Here, the interpretation results when the dither image output method is the SEF method are shown.

  FIG. 5 illustrates the page buffer area. As shown in the figure, in the page buffer area 12, an x axis and a y axis perpendicular to the x axis are set as coordinate axes. The position in the page buffer area 12 is specified by the x coordinate value and the y coordinate value. The x-axis direction is the scanning direction, and the y-axis direction is the sub-scanning direction. When the output method is the LEF method, the x axis and the y axis are interchanged.

  As shown in the top interpretation result, a rectangular area having the start point as the start point S1 and the end point as the end point E1 is specified as the drawing target area B1 corresponding to the virtual drawing target area A1, and the gradation value is “5”. Is specified as the gradation value corresponding to the virtual gradation “0.98”. Further, as shown by the second interpretation result from the top, a rectangular area having the start point as the start point S2 and the end point as the end point E2 is specified as the drawing target area B2 corresponding to the virtual drawing target area A2, and the gradation value “55” is specified as the gradation value corresponding to the virtual gradation “0.78”. Further, as shown in the third interpretation result from the top, a rectangular area having the start point as the start point S3 and the end point as the end point E3 is specified as the drawing target area B3 corresponding to the virtual drawing target area A3, and the gradation value “105” is specified as the gradation value corresponding to the virtual gradation “0.58”. Further, as shown by the fourth interpretation result from the top, a rectangular area having the start point as the start point S4 and the end point as the end point E4 is specified as the drawing target area B4 corresponding to the virtual drawing target area A4, and the gradation value “155” is specified as the gradation value corresponding to the virtual gradation “0.38”. As shown in the bottom interpretation result, a rectangular area having a start point S5 and an end point E5 is specified as a drawing target area B5 corresponding to the virtual drawing target area A5, and the gradation value “ “0” is specified as the gradation value corresponding to the virtual gradation “1.00”. Each drawing target area has a different gradation value.

  As a result of interpreting each drawing command, a dither image of the page image is drawn in the page buffer area 12. This point will be described later.

[Dither Matrix]
Here, the dither matrix used in the page printer 2 will be described. FIG. 6 is a diagram illustrating a dither matrix. This dither matrix is a threshold value matrix including threshold values set at respective positions in the page buffer area 12. This dither matrix is a threshold matrix in which unit threshold matrixes having a width in the x-axis direction of “L” and a width in the y-axis direction of “F” (reference distance) are arranged in a grid pattern. The value of a certain threshold value is the same as the threshold value at a position away from the threshold value by “F” in the y-axis direction. FIG. 7 illustrates a unit threshold value matrix.

  In the page printer 2, a pattern image of each gradation value is stored in the storage unit 6. That is, the storage unit 6 stores a binary image obtained by binarizing an image in which the area of the dither matrix is filled with the gradation value as the pattern image of the gradation value. Note that a binary image obtained by binarizing an image in which the area of the unit threshold matrix is filled with the gradation value by the unit threshold matrix may be stored as the gradation value pattern image.

[processing]
Hereinafter, a process executed by the control unit 4 (drawing unit) in accordance with the image processing program in order to draw a dither image of a page image in the page buffer area 12 will be described. FIG. 8 is a flowchart illustrating the process executed by the control unit 4. This process is executed when PDL data is input.

  First, the control unit 4 sets the gradation value “g” to “0” (S101).

  Then, the control unit 4 sequentially reads each drawing command described in the PDL data from the top, and sequentially executes the steps after S102 every time the drawing command is read. Hereinafter, steps after S102 will be described. The read drawing command is called a drawing command X.

  The control unit 4 determines whether or not the drawing command X is a rectangular drawing command (S102). For example, the control unit 4 determines whether or not the character string “rectfill” is included in the drawing command X.

  When the drawing command X is a rectangular drawing command (Y in S102), the control unit 4 (detecting means) interprets the drawing command X, and from the virtual drawing target area and the virtual gradation, the rectangular drawing target area X and A gradation value X is specified (S103). In the following description, the coordinates of the start point SX of the drawing target area X are described as (sx, sy), and the coordinates of the end point EX of the drawing target area X are described as (ex, ey).

  Then, the control unit 4 (detection means) determines whether or not the width of the drawing target area X in the sub-scanning direction (that is, the y-axis direction) is larger than the “F” (S104). Specifically, the control unit 4 determines whether or not the value of “ey−sy + 1” is greater than “F”.

  When the width of the drawing target area X in the sub-scanning direction is larger than “F” (Y in S104), the control unit 4 (detection means) determines whether or not the gradation value “g” is “0” ( S105).

  When the gradation value “g” is “0” (Y in S105), the control unit 4 (detecting means) performs spool processing, and the drawing target area X and gradation value X are converted to the current gradation value “g”. And stored in the storage unit 6 (S106). Then, the control unit 4 (detection means) increments the gradation value “g” (S107).

  On the other hand, when the gradation value “g” is equal to or greater than “1” (N in S105), the control unit 4 (detecting means) draws the drawing target area stored in the storage unit 6 in association with the gradation value “g−1”. (Hereinafter referred to as a drawing target area Y) is read out. Then, the control unit 4 (detection means) determines that “the difference between the y coordinate value sy of the start point SY of the drawing target area Y and the y coordinate value sy of the start point SX of the drawing target area X” and “the end point EY of the drawing target area Y”. It is determined whether or not both the difference between the y-coordinate value ey and the y-coordinate value ey of the end point EX of the drawing target area X are “0” (S108). That is, the control unit 4 determines that the position sy of the upper side of the drawing target area X and the position syy of the upper side of the drawing target area Y are the same, and the position ey of the lower side of the drawing target area X and the lower side of the drawing target area Y It is determined whether or not the position “eyy” is the same.

  Further, the control unit 4 (detection means) determines that “the absolute value of the difference between the x coordinate value syx of the start point SY of the drawing target area Y and the x coordinate value ex of the end point EX of the drawing target area X” and “the drawing target area Y It is determined whether or not any one of “the absolute value of the difference between the x coordinate value eyx of the end point EY” and the x coordinate value sx of the start point SX of the drawing target area X is “1” (S109). . That is, the control unit 4 selects one of the combination of the right side of the drawing target area X and the left side of the drawing target area Y and the combination of the left side of the drawing target area X and the right side of the drawing target area Y. It is determined whether or not two sides related to the combination are adjacent to each other.

  It is determined that “both the difference between the coordinate value sy and the coordinate value sy and the difference between the coordinate value ey and the coordinate value ey are“ 0 ”” (Y in S108), and “the coordinate value syx and the coordinate value When it is determined that one of the absolute value of the difference from ex and the absolute value of the difference between the coordinate value eyx and the coordinate value sx is “1” (Y in S109), the control unit 4 The process proceeds to step S106.

  On the other hand, when it is determined that “the difference between the coordinate value sy and the coordinate value sy and the difference between the coordinate value ey and the coordinate value ey are not“ 0 ”” (N in S108), or “the coordinate value syx When the absolute value of the difference between the coordinate value ex and the absolute value of the difference between the coordinate value eyx and the coordinate value sx is determined not to be “1” (N in S109), the control unit 4 (detecting means) ) Executes a subroutine S (S110).

  FIG. 9 is a flowchart illustrating the subroutine S. In the subroutine S, the control unit 4 (detection means) determines whether or not the gradation value “g” is “2” or more (S201). That is, the control unit 4 (detection means) detects the presence of the gradation area by executing the step of S201.

  Here, the gradation area is a rectangular area included in the page buffer area 12 and parallel to the main scanning direction (that is, the x-axis direction), and has a width in the sub-scanning direction (that is, the y-axis direction). This is an area that is larger than “F”, changes in gradation according to the position in the main scanning direction, and does not change according to the position in the sub-scanning direction at any position in the main scanning direction. Specifically, when the gradation value “g” is “2” or more (Y in S201), the control unit 4 is stored in the storage unit 6 in association with each of “0” to “g−1”. A rectangular area connecting a plurality of drawing target areas is detected as a gradation area.

  When the gradation value “g” is “1” (N in S201), the control unit 4 (drawing unit) stores the drawing target area (hereinafter, the drawing target area) stored in the storage unit 6 in association with “0”. Z) and the gradation value (hereinafter referred to as gradation value Z) are read out, and a dither image in the drawing target area Z is drawn based on the pattern image associated with the gradation value Z (S202). .

  Then, the control unit 4 (detection means) updates the gradation value “g” to “0” (S203).

  On the other hand, when the gradation value “g” is equal to or greater than “2” (Y in S201), the control unit 4 (drawing means) executes the subroutine S1 (S204) and proceeds to the step of S203.

  FIG. 10 is a flowchart illustrating the subroutine S1. In the subroutine S1, the control unit 4 (generating unit) generates a buffer for a unit rectangle whose width in the main scanning direction is “F” and whose width in the sub scanning direction is the same as that of the gradation area in the storage unit 6 (S301). ).

  Then, the control unit 4 (generating unit) sets the region for the unit rectangle included in a part of the gradation region as the attention region (partial region). In the case of this embodiment, the control unit 4 sets a unit rectangle area including the upper side of the gradation area as the attention area.

  Then, the control unit 4 performs raster scanning on the attention area, and based on the pattern image of each gradation value of the drawing target area included in the gradation area, the dither image (hereinafter, unit dither image) of the attention area. Is drawn in the buffer (S302). That is, the control unit 4 (generation unit) generates a unit dither image. Note that the pattern image (more specifically, a part of the pattern image) is read out the same number of times as the number “n” of the drawing target areas included in the gradation area per scan. Therefore, since the width of the attention area in the sub-scanning direction is “F”, the data is read ““ n ”ד F ”” times in the entire attention area.

  FIG. 11 is a diagram illustrating a region of interest. Here, the case where the area | region 14 which connected drawing object area | region B1, B2, B3, B4 shown in FIG. 5 was detected as a gradation area | region is taken up as an example. “R” indicates the width of the gradation area in the main scanning direction.

  In this case, in step S301, a buffer for a unit rectangle having a width “F” in the main scanning direction and a width “R” in the sub-scanning direction is generated, and the shaded area in the gradation area is noted. It will be set as an area.

  Then, the control unit 4 (gradation drawing means) draws the dither image in the gradation area based on the unit dither image by raster scanning the gradation area (S303). Thus, the control unit 4 tiles the unit dither image in the gradation area. Note that a unit dither image (more specifically, one line of the unit dither image) is read once per scan. Therefore, if the width of the gradation area in the sub-scanning direction is ““ h ”ד F ””, “h” × “F” ”data is read out in the entire gradation area.

  FIG. 12 conceptually shows the drawing of the dither image in the gradation area. A unit dither image is drawn in each of the region 16a, the region 16b, the region 16c, the region 16d, and the region 16e.

  If the width of the drawing target area X in the sub-scanning direction is equal to or smaller than “F” (N in S104), the control unit 4 executes a subroutine S2 (S111). If the drawing command X is a drawing command other than the rectangular drawing command (N in S102), the control unit 4 executes a subroutine S3 (S112).

  FIG. 13 is a flowchart illustrating the subroutine S2. In the subroutine S2, the control unit 4 determines whether or not the gradation value “g” is “0” (S401).

  When the gradation value “g” is “0” (Y in S401), the control unit 4 (drawing unit) draws a dither image in the drawing target area X based on the pattern image of the gradation value X (S402). ).

  On the other hand, when the gradation value “g” is not “0” (N in S401), the control unit 4 executes the subroutine S (see FIG. 9) (S403) and then draws the dither image in the drawing target area X. (S402).

  FIG. 14 is a flowchart illustrating the subroutine S3. In the subroutine S3, the control unit 4 determines whether or not the gradation value “g” is “0” in the same manner as in step S401 (S501).

  When the gradation value “g” is “0” (Y in S501), the control unit 4 (rendering unit) interprets the rendering command X (S502) and based on the pattern image of the gradation value indicated by the interpretation result. Then, a dither image of the area indicated by the interpretation result is drawn (S503).

  On the other hand, when the gradation value “g” is not “0” (N in S501), the control unit 4 executes the subroutine S (see FIG. 9) (S504), and proceeds to the step of S502.

  As described above, the dither image obtained by binarizing the page image with the dither matrix is drawn in the page buffer area 12. Then, the dither image drawn in the page buffer area 12 is printed on the printing paper by the image forming unit 8.

  By the way, there is no lack of a method for drawing a dither image in a gradation area without using a unit dither image. Usually, a method of rendering a dither image in the gradation area by performing the same process as in step S302 so as to raster scan the gradation area instead of the attention area can be considered. However, in this case, as described above, data is read as many times as the number “n” of the drawing target areas in the gradation area for each scan, and therefore ““ n ”ד h ”ד F ” “” Times of data reading are performed. As described above, ““ h ”ד F ”” is the width of the gradation area in the sub-scanning direction.

  Therefore, when the value of “n” is large, that is, when the pitch of the gradation change in the main scanning direction is short, the processing load related to drawing the dither image in the gradation area becomes large.

  In this regard, in this page printer 2, as described above, ““ n ”ד F ”” times of data reading are performed in step S302, and “h” × “F” times are read in step S303. Is read out. As a result, data is read only “(“ h ”+“ n ”) ד F ”” times. Therefore, the processing load related to the drawing of the dither image in the gradation area can be reduced.

  The embodiment of the present invention is not limited to the above embodiment.

  For example, the control unit 4 (detection means) determines whether or not the drawing command X is a so-called gradation drawing command, and when the drawing command X is a gradation drawing command, a rectangle derived from the interpretation result of the drawing command X It may be determined whether or not the width of the region in the sub-scanning direction is larger than “F”. In this case, the rectangular area determined as having a width in the sub-scanning direction larger than “F” may be detected as a gradation area, and the subroutine S1 shown in FIG. 10 may be executed. In this case, each of “a plurality of rectangular regions having different gradation values” included in the gradation region corresponds to “a drawing target region included in the gradation region” in the above embodiment.

  For example, the image forming unit 8 may be realized by an image forming apparatus separate from the control unit 4 and the storage unit 6.

  The page description language may be any page description language.

  2 page printer, 4 control unit, 6 storage unit, 8 image forming unit, 10 current page plane, 12 page buffer area, 14 gradation area, 16a, 16b, 16c, 16d, 16e area.

Claims (3)

A drawing means for drawing a dither image obtained by binarizing an output target image with a dither matrix based on image information described in a page description language in a storage means;
Output means for outputting a dither image drawn in the storage means;
Including
The drawing means includes
A width in the sub-scanning direction that is parallel to the main scanning direction and perpendicular to the main scanning direction is larger than a reference distance that is a width in the sub-scanning direction of the dither matrix and is at a position in the main scanning direction. Detecting means for detecting the presence of a rectangular gradation region whose gradation changes in response, based on the image information, in an image region corresponding to the output target image;
When the detection means detects the presence of the gradation area, the gradation area is a part of the gradation area, the width in the sub-scanning direction is the reference distance, and the width in the main scanning direction is Generating means for generating a dither image of a partial area having the same width as the gradation area;
Gradation drawing means for drawing the dither image of the gradation area in the storage means based on the dither image generated by the generation means;
An image processing system. The first threshold value included in the dither matrix is the same as the second threshold value included in the dither matrix and located at a position away from the first threshold value in the sub-scanning direction by the reference distance.
The image processing system according to claim 1. Drawing means for drawing a dither image obtained by binarizing an output target image with a dither matrix based on image information described in a page description language in a storage means;
Output means for outputting a dither image drawn in the storage means;
Function as a computer
The drawing means includes
A width in the sub-scanning direction that is parallel to the main scanning direction and perpendicular to the main scanning direction is larger than a reference distance that is a width in the sub-scanning direction of the dither matrix and is at a position in the main scanning direction. Detecting means for detecting the presence of a rectangular gradation region whose gradation changes in response, based on the image information, in an image region corresponding to the output target image;
When the detection means detects the presence of the gradation area, the gradation area is a part of the gradation area, the width in the sub-scanning direction is the reference distance, and the width in the main scanning direction is Generating means for generating a dither image of a partial area having the same width as the gradation area;
Gradation drawing means for drawing the dither image of the gradation area in the storage means based on the dither image generated by the generation means;
A program characterized by

Images