JP2000066658A - Image processor and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the readability of characters irrespective of a font used. SOLUTION: A font-attributive information acquiring means 1 acquires attributive information on the font of a character contained in data i1 of a processing object. A display parameter difference calculating means 2 calculates the differences of display parameters relating to the character contained in the data i1 the object and identifying degree of its background. A reference value calculating means 3 calculates a reference value based on the attributive information of the font. A display parameter changing means 4 compares the difference of the display parameter with the reference value to change the display parameter of the character if necessary. A converting means 5 converts the character changed in the display parameter and other drawing data into display format data (for example, bit map data).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and a recording medium, and more particularly to an image processing apparatus for converting drawing data including characters into data in a display format, and converting drawing data including characters into data in a display format. The present invention relates to an image processing apparatus that performs screen processing and a computer-readable recording medium that stores a program that causes a computer to execute such processing.

[0002]

2. Description of the Related Art Image data including characters is converted to CRT (Cathod).
e Ray Tube) When displaying on a display device such as a monitor or a printer, the font data of the character and the image data are combined and converted into display format data (for example, bitmap data, etc.), and then the CRT or the like is displayed. It was displayed and output on recording paper.

When the display colors of characters and the background image are close to each other, the legibility of the characters may be reduced. Therefore, in order to improve the legibility of characters, a method has been proposed in which an image to be displayed is divided into a character region and an image region, and edge enhancement processing or the like is performed only on the character region.

For example, Japanese Patent Application Laid-Open No. Hei 9-167222 discloses that image data described in a page description language is divided into two parts: (A) a character area and a line drawing area, and (B) an image area. There is disclosed an invention that improves the legibility of characters (or line drawings) by increasing the contrast of only the region and the line drawing region or enhancing the edges.

[0005]

However, in an image in which the character area and the image area overlap, the emphasis processing performed on the character area also enhances the image area serving as the background of the character. There has been a problem that legibility may not be improved.

Therefore, Japanese Patent Laid-Open No. Hei 7 (1995) discloses an invention in which the color of a character is compared with that of a background and the character is emphasized by changing the color of the character.
No. 2,569,722. According to the present invention, a character and a background are compared, and when the density and the color are within a predetermined range, the density and the color of the character are changed.
Improves the legibility of characters.

However, the legibility of characters may be deteriorated not only when the colors of the characters and the background are close but also when the characters are small or the line width of the characters is thin. In order to make the characters clear even in such a case, Japanese Patent Application Laid-Open
There is a problem that the method described in US Pat. No. 2,569,72 is insufficient.

When screen processing is performed on image data, depending on the size of the screen,
There is a problem that characters having a small size and characters having a small line width become unclear.

[0009] The present invention has been made in view of such a point, and the type and size of a font to be used, or
Provided is an image processing apparatus capable of always displaying highly legible characters irrespective of a density difference or a color difference from a background.

Another object of the present invention is to provide an image processing apparatus capable of always displaying highly legible characters regardless of the size of a screen used.

[0011]

According to the present invention, in order to solve the above-mentioned problems, an image processing apparatus for converting drawing data including characters into display format data acquires font attribute information corresponding to the characters. Font attribute information acquiring means, display parameter difference calculating means for calculating a difference between display parameters relating to the degree of identification of the character and its background, and the attribute information of the font and the difference between the display parameters, Display parameter changing means for changing the display parameter of the character as necessary, the character whose display parameter has been changed, and other drawing data,
An image processing apparatus comprising: a conversion unit that converts data into a display format data.

Here, the font attribute information acquiring means acquires the attribute information of the font corresponding to the character. The display parameter difference calculation means calculates a difference between a display parameter related to the degree of discrimination between a character and its background. The display parameter changing means changes the display parameter of the character as needed according to the attribute information of the font and the difference between the display parameters. The conversion means converts the characters whose display parameters have been changed and other drawing data into display format data.

Also, in an image processing apparatus for converting drawing data including characters into data in a display format and performing screen processing, screen size obtaining means for obtaining information on the size of the screen; Display parameter difference calculating means for calculating a difference between display parameters related to the degree of discrimination, display parameters for changing the display parameters of the characters as necessary according to the information on the screen size, and the difference between the display parameters. Changing means, converting means for converting the characters whose display parameters have been changed, and other drawing data into data in display format, and performing screen processing on the data in display format obtained by the converting means. An image processing apparatus, comprising: .

Here, the screen size obtaining means obtains information on the size of the screen. The display parameter difference calculation means calculates a difference between a display parameter related to the degree of discrimination between a character and its background. The display parameter changing means changes the display parameter of the character as needed according to the information on the screen size and the difference between the display parameters. The conversion means converts the characters whose display parameters have been changed and other drawing data into display format data. The screen processing means performs a screen processing on the data in the display format obtained by the conversion means.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a principle diagram for explaining the operation principle of the present invention.

As shown in FIG. 1, an image processing apparatus according to the present invention includes a font attribute information acquiring unit 1, a display parameter difference calculating unit 2, a reference value calculating unit 3, a display parameter changing unit 4, and a converting unit 5. It is constituted by.

Here, the font attribute information obtaining means 1
The attribute information of the font corresponding to the character (character “A” in this example) included in the data i1 to be processed is acquired.

As the font attribute information, a font size, a font type, and a font typeface are used. The display parameter difference calculation means 2 calculates a difference between a display parameter relating to the degree of discrimination between a character included in the data i1 to be processed and its background (in this example, a triangle).

Here, the degree of discrimination indicates the degree of ease of distinguishing characters from the background. Further, as a display parameter related to the degree of discrimination, for example, display density, brightness, color difference, or the like is used. Furthermore, legibility means that a character is recognizable as that character.

The reference value calculation means 3 calculates a reference value, which is used as a criterion for determining when the display parameter is changed by the display parameter changing means 4, from the font attribute information. The reference value is set to a small value when the degree of character recognition is high.

As a method of calculating the reference value, for example, when the font size is large, the legibility of the character is high, so a smaller reference value is set as compared with the case where the font size is small. When the font type is Gothic, a small reference value is set because the legibility is high.
Furthermore, a small reference value is set even when the font typeface is a bold type because the readability is also high.

The display parameter changing means 4 compares the difference between the display parameters and the reference value. For example, when the difference between the display parameters is smaller than the reference value, the display of the character in the direction in which the difference between the display parameters increases. Change parameters.

For example, when the readability of the font to be used is low (when the reference value is large), when the difference between the display parameters is small, and when the display density of the character is smaller than that of the background, the display of the character is performed. The density is changed to a smaller value. Conversely, if the display density of the character is higher than the background, the display density of the character is changed to a higher value.

The conversion means 5 converts the characters whose display parameters have been changed and other drawing data into display format data (for example, bitmap data). Next, the operation of the above principle diagram will be described.

The font attribute information acquiring means 1 acquires the attribute information of the font corresponding to the character data "A" included in the data i1 to be processed. For example, as the attribute information, it is acquired that the font size is “12 points”, the font type is “Mincho”, and the font type is “bold”.

The reference value calculation means 3 calculates a reference value from the acquired attribute information. That is, the reference value calculation means 3 calculates the reference value by appropriately adding the values assigned to the respective attributes of the font and performing predetermined conversion on the obtained values.

The display parameter difference calculating means 2 calculates the difference between the display density of the character "A" included in the data i1 to be processed and the display density of the background. When the difference between the display parameters is smaller than the reference value, the display parameter changing means 4 changes the display parameters of the characters.

For example, when the display density of the character is lower than that of the background and the difference between the display parameters is less than the reference value, the display of the character is further reduced so that the display density of the character is further reduced. Parameters are changed.

Conversely, when the display density of the character is higher than that of the background and the difference between the display parameters is less than the reference value, the display density of the character is further increased so as to be higher. Display parameters are changed.

The conversion means 5 outputs data i1 to be processed.
Is converted into bitmap data which is data in a display format. The bitmap data i2 obtained as described above is displayed and output as an image on a CRT or a recording sheet, for example.

As described above, according to the present invention, the display parameters of characters are changed in consideration of the font attributes of the characters, so that the readability is always constant regardless of the font size, type or typeface. High display can be performed.

Next, an embodiment of the present invention will be described. FIG. 2 is a block diagram showing a configuration example of the embodiment of the present invention. As shown in FIG. 1, the image processing apparatus according to the present invention includes an edge list generation unit 20, a character background color extraction unit 30, a character color conversion unit 40, and a bitmap development unit 50.

In FIG. 2, the print data 10 is described in a description language that can be processed by the image processing apparatus, and is created by a personal computer or workstation (not shown) created by an application program for creating or editing a document. It was generated from the data. The description language targeted in this embodiment is, for example, GD
I (Graphics Device Interface), but Acro
bat (Portable Document Forma)
t) or a page description language typified by PostScript.

The drawing objects drawn by the print data 10 include characters, figures (line drawings), and rasters. Here, it is assumed that the raster is composed of "raster data" which is image data and "contours" indicating the periphery of the raster data.

The edge list generation unit 20 firstly outputs characters,
A display list for drawing the outline of a figure or raster is generated for each drawing object, and then the obtained display list is synthesized, and the starting and ending points of the drawing object included in each scan line and the Generate an edge list including color information and the like.

When the drawing object is a character, the character background color extraction unit 30 specifies the background and extracts the color (background color) from the edge list. The character color conversion unit 40
The character color is converted according to the background color extracted by the character background color extraction unit 30 and the attribute of the character.

The bitmap developing section 50 develops the edge list (the edge list including the character subjected to the color conversion) supplied from the character color converting section 40 into a bitmap. Next, details of a main part of the image processing apparatus will be described.

First, the edge list generator 20 will be described in detail. FIG. 3 is a block diagram illustrating a configuration example of the edge list generation unit 20. As shown in the figure, the edge list generation unit 20 includes a print data interpretation unit 20a, a display list processing unit 20b, a raster data processing unit 20b.
c, a raster data buffer 20d, and an edge list processing unit 20e.

Here, the print data interpreter 20a cuts out a token from the input print data in accordance with the syntax of the description language. Then, the token is interpreted, and the token is converted into a corresponding internal instruction or its argument.

The internal commands include a drawing command for instructing drawing of outlines of characters, figures, and rasters, and a drawing state command for setting information necessary for drawing such as color and line attributes. .

The print data interpreting section 20a selects an internal command corresponding to a character, a graphic, and a contour of a raster among the internal commands generated in this way, and supplies it to the display list processing section 20b. Note that a drawing command for drawing raster data and the raster data itself are supplied to the raster data processing unit 20c.

First, the display list processing unit 20b generates edge data constituting the outline of an object to be drawn in accordance with a drawing command of a character and a figure. Then, from the obtained edge data, a display list including the start point and the slope of the edge and the number of intersections between the edge and the scan line is generated and supplied to the edge list processing unit 20e. Further, based on the vertical and horizontal sizes of the raster data transferred from the print data interpreting unit 20a to the raster data processing unit 20c, a display list indicating the outline of the raster data is generated, and the edge list processing unit 20e is generated.
To supply.

The raster data processing unit 20c performs coordinate conversion on the target raster data in accordance with the raster drawing command, and converts the color space of the raster data into the color space of the output device. And outputs it to the raster data buffer 20d.

The raster data buffer 20d temporarily stores the raster data supplied from the raster data processing unit 20c. The edge list processing unit 20e includes a display list processing unit 20b and a raster data processing unit 20c.
Is converted into an edge list including a start point, an end point, and color information of each scan line.

Next, the operation of the above embodiment will be described. Now, print data 1 described by GDI or the like
Assume that 0 has been input. Then, the print data interpreter 20
First, a token is cut out from the print data 10 and
By interpreting the token, internal instructions and arguments are obtained.

The print data interpretation unit 20a supplies the obtained internal commands and arguments corresponding to the characters and figures to the display list processing unit 20b, and outputs the ones corresponding to the raster to the raster data processing. To the unit 20c. Further, information indicating the size of the raster data is supplied to the display list processing unit 20b.

The display list processing unit 20b generates a display list for each drawing object from internal commands and arguments supplied from the print data interpretation unit 20a.

FIG. 4 is a diagram showing an example of the data structure of a display list corresponding to characters. As shown in this figure, the display list corresponding to the character is composed of a header section 60, a list section 61, and a connection cell 62.

The header section 60 includes TypeID (in this case, ID indicating a character) indicating the type of the drawing object,
Color information indicating the type of color used to fill the drawing object,
It is composed of character attribute information to be described later, the number of y-lists that is the total number of y buckets, the number of linked cells that is the total number of cells linked to each y-list, and a pointer to the display list of the next drawing object. I have.

The list section 61 is composed of y buckets and connected cells. The y bucket includes a scan line y corresponding to the y coordinate value of the start point of the input vector data of each drawing object, and a cell pointer that is a pointer to the first connected cell 62. It should be noted that the y bucket having no connected cell 62 is not registered in the list unit 61.

The connected cell 62 includes the x coordinate value of the starting point of the vector data of each input drawing object, Δx which is an increment value of x per scanning line of the vector data, and the scanning line of the scanning line intersecting the vector data. It is composed of a number Δy and a connection flag indicating whether or not different vector data starting from the scanning line y exists.

As the connection flag, a flag "1" is added when the next connection cell exists, and a flag "0" indicating EOC (End Of Cell) when the next connection cell is the last. "Is added.

Next, details of the character attribute information of the header section 60 will be described. The character attribute information is information relating to whether or not the readability of the font to be used is high, and is calculated using the font size, font type, and font typeface as parameters.

Assuming that parameters relating to the font size of the character are v1 and parameters relating to the font type and font type are v2 and v3, respectively, the character attribute information v is calculated by the following equation.

V = f (v1, v2, v3) (1) In this embodiment, since the sum function is adopted as the function f, the equation (1) is expressed as follows.

V = v1 + v2 + v3 (2) Note that v1 to v3 are obtained as follows. First,
v1 is obtained as follows. That is, assuming that the font size is s (point), v1 is determined by the value of s as follows.

If s <7 v1 = 3 If 7 ≦ s <10 v1 = 2 If 10 ≦ s <13 v1 = 1 If 13 ≦ s v1 = 0 Next, v2 depends on the type of font. It is determined as follows.

When the font is Gothic font v2 = 0 When the font is a thin font v2 = 2 When the font is any other font v2 = 1 Finally, v3 is determined as follows according to the font typeface.

When the typeface is a Bold type v3 = 0 When the typeface is an Italic type v3 = 2 When the typeface is any other type v3 = 1 And v1 to v3 obtained as described above are obtained by the equation (2).
To obtain character attribute information v.

The value of v thus obtained is stored in the header section 60 as character attribute information. Next, a display list of graphics will be described.

FIG. 5 is a diagram showing an example of the data structure of a display list corresponding to a figure. In the figure,
The header section 70 has a Type indicating the type of the drawing object.
eID (in this case, an ID indicating a figure), color information indicating the type of color used to fill the drawing object, the number of y lists, which is the total number of y buckets, and the number of connected cells, which is the total number of cells connected to each y list , And a pointer to a display list of the next drawing object.

The list section 71 includes the y bucket and the connected cell 7
2, which is similar to the case of the character display list. Next, the raster display list will be described.

FIG. 6 is a diagram showing an example of the data structure of a display list corresponding to a raster. In the figure, a header section 80 has a T indicating the type of the drawing object.
typeID (in this case, an ID indicating a raster), information indicating the data size of the raster data (the number of bits per pixel), a data address indicating a head address of data stored in the raster data buffer 20d, and each y list And the pointer to the display list of the next drawing object.

The list section 81 includes the y bucket and the connected cell 8
2, which is the same as the display list of characters and graphics. The list portion 81 of the raster display list stores data for drawing the outline of the raster, and the header portion 80 stores information on raster data to be attached to the drawn outline. Have been.

Returning to FIG. 3, the display list of characters, graphics, and rasters generated by the display list processing unit 20b is stored in the edge list processing unit 20e.
Supplied to

On the other hand, the raster data output from the print data interpreting section 20a and the internal command corresponding to the raster data are supplied to the raster data processing section 20c. The raster data processing unit 20c performs coordinate conversion on the target raster data according to the supplied internal command, and performs processing such as color space conversion for converting the color space of the raster data to the color space of the output device. And outputs it to the raster data buffer 20d.

The raster data buffer 20d temporarily stores the raster data supplied from the raster data processing unit 20c, and reads out and supplies the raster data as required when requested by the edge list processing unit 20e.

The edge list processing section 20e converts the display list into an edge list shown in FIG. Here, the edge list is obtained by eliminating and overlapping display lists, and indicates an area occupied by each object on a scan line.

In the example shown in FIG. 7, the third y bucket has a character edge list 90 and a figure edge list 9.
1, and the edge list 92 of the raster are connected in order. Therefore, it can be seen that characters, graphics, and rasters are sequentially arranged on the third scanning line.

The character edge list 90 includes a drawing object determination flag 90a, a start point 90b, an end point 90c, color information 90d, character attribute information 90e, and a connection flag 9
0f.

The drawing object determination flag 90a is for determining the type of the drawing object, and is set to "00" in the case of a character. The start point 90b and the end point 90c indicate the start point and the end point of the character area on the scanning line. The color information 90d is configured by color information (for example, RGB values or the like) indicating how many colors are to be used to paint the drawing object. The character attribute information 90e is a value obtained by the above equation (2). Connection flag 90f
Indicates whether the next drawing object exists on the same scanning line. Note that a flag “1” is added to the connection flag 90f when the next drawing object exists, and a flag “0” indicating EOC is added to the connection flag 90f when the connection object is the last drawing object.

The graphic edge list 91 includes a drawing object determination flag 91a, a start point 91b, an end point 91c, color information 91d, and a connection flag 91e. The drawing object determination flag 91a is for determining the type of the drawing object, and is set to “01” in the case of a graphic. Start point 91b and end point 91c
Indicates the start point and end point of the graphic area on the scan line. The color information 91d is configured by color information indicating the color of the drawing object to be painted. Connection flag 91e
Indicates whether the next drawing object exists on the same scanning line.

The raster edge list 92 includes a drawing object determination flag 92 a, a start point 92 b, an end point 92 c, a pointer 92 d to raster data, and a connection flag 9.
2e.

The drawing object determination flag 92a is for determining the type of the drawing object, and is set to "10" in the case of a raster. The start point 92b and the end point 92c indicate the start point and the end point of the raster area on the scan line. The pointer 92d to the raster data is
This is a pointer indicating the address of the raster data buffer 20d corresponding to b. The connection flag 92e indicates whether the next drawing object exists on the same scan line.

The areas specified by the starting point and the ending point of each object are independent of each other and have no overlapping part. Next, a method of generating such an edge list will be described.

The edge list processing unit 20e performs processing for developing the display list supplied from the display list processing unit 20b and then synthesizing the display list. Details of this processing will be described below.

FIG. 8 is a diagram showing an example of developing a display list. 8A shows a display list of a figure (triangle), and FIG. 8B shows a display list of FIG.
It is the figure which expanded the display list of (A).

In this example, two cells are connected to the bucket y1 in the list section. The first cell has a starting point of x4, an inclination of △ x ', and an intersection number with the scanning line of △ y'. In the second cell, the starting point is x4, the inclination is Δx ”, and the number of intersections with the scanning line is Δy”.

When these cells are expanded, a figure (triangle) shown in FIG. 8B is obtained. Next, a starting point and an ending point in each scanning line are obtained from the graphic obtained by developing. That is, as can be seen from FIG. 8B, when the y coordinate is 1, the start point and the end point are x4. When the y coordinate is 2, the start point and the end point are x3 and x5, and more specifically, x4 + {x ', x4 + Δx ". Similarly, all the x coordinate values intersecting the scanning line are obtained.

Subsequently, an edge list having information on the starting point, the ending point, and the color for each scanning line is generated from the obtained x coordinate values. FIG. 9 shows an example of generating an edge list. In the figure, when the y bucket is y1, the drawing object determination flag is “01” because the TypeID of the display list is a graphic, the start point and the end point are x4, the color is c, and the connection flag is another line on the same scan line. Since there is no edge, it becomes EOC.

When the y bucket is y2, the drawing object discrimination flag is "01" because it is a figure, and the start and end points are x3 and x5 and the color is c. In addition, the connection flag becomes EOC because there is no other edge on the same scan line.

Similarly, an edge list is generated from all y buckets in which cells exist. Next, a method of synthesizing an edge list will be described. FIG. 10 is a diagram illustrating an example of combining edge lists. In the figure, when the edge list of the character (FIG. 10B) is superimposed on the edge list of the graphic (FIG. 10A), the x-coordinate value of the graphic is 10
To 20 and the x coordinate value of the character is 15 to 25, so that the x coordinate values 15 to 20 overlap. In that case, the superimposed portion of the lower drawing object is deleted in accordance with the order in which the drawing objects are superimposed.

Assuming that the figure is below, the x-coordinate value of the figure is changed from 10 to 15. As a result, the combined edge list is as shown in FIG. Similarly, all edge lists are combined.

As described above, the edge list processing unit 20e
Is supplied to the character background color extraction unit 30 shown in FIG. Character background color extraction unit 30
Extracts the background color of the character (background color) from the edge list. This processing will be described with reference to FIG.

FIG. 11 is a flowchart for explaining an example of the processing executed by the character background color extraction unit 30. When this flowchart is started, the following processing is executed. [S1] The character background color extraction unit 30 checks the y bucket in which the connected cell first exists, and obtains the first connected cell of the y bucket. [S2] The character background color extraction unit 30 determines whether or not the acquired connected cell is a character. That is, the character background color extraction unit 30 determines whether or not the drawing object determination flag of the acquired connected cell is “00”. If the flag is “00”, the process proceeds to step S3; otherwise, the process proceeds to step S3. Goes to step S7. [S3] The character background color extraction unit 30 acquires the next connected cell. [S4] The character background color extraction unit 30 determines whether or not the obtained linked cell is adjacent to the character. That is, the character background color extraction unit 30 determines that the connected cell determined to be a character in step S2 is adjacent to the connected cell acquired in step S3, and
If the connected cell obtained in step S3 is a connected cell other than a character, the process proceeds to step S5 assuming that the background of the character has been detected, and otherwise proceeds to step S6. [S5] The character background color extraction unit 30 converts the color information (character color) of the connected cell determined as a character in step S2 and the color information (background color) of the connected cell acquired in step S3 into a character color conversion unit. Supply to 40. [S6] The character background color extraction unit 30 sets the background color to “0” and converts the color information (character color) of the connected cell determined as a character in step S2 and the background color (= 0) into character color conversion. Supply to the unit 40.

There are two cases of branching to step S6, that is, a case where characters overlap each other and a case where there is no background. In such a case, the background color is set to "0". To prevent character color conversion from being performed. [S7] The character background color extraction unit 30 determines that the connection flag is EOC.
Is determined, and in the case of EOC, step S8
Otherwise, to step S9. [S8] The character background color extraction unit 30 determines whether or not there is an unprocessed connected cell. If there is, the process proceeds to step S10; otherwise, the process ends. [S9] The character background color extraction unit 30 acquires the next connection flag, and returns to step S2. [S10] The character background color extraction unit 30 acquires the first connected cell of the next y bucket, and returns to step S2.

According to the above processing, for example, FIG.
As shown in (A), when a figure having a background color b and a character “A” having a character color a are superimposed, the character color a and the background color b are extracted, It is supplied to the character color conversion unit 40.

Here, in FIG. 12B, the n-th y
Five connected cells are connected to the bucket yn, and the first, third, and fifth connected cells correspond to the background, while the second and fourth connected cells correspond to the characters. are doing. In this case, since the connected cell of the character and the background (image) are adjacent to each other, b is obtained as the background color from the first, third, and fifth connected cells. A is obtained as the character color from.

The character color and the background color extracted as described above are supplied to the character color conversion unit 40. The character color conversion unit 40 first calculates the color difference between the background color and the character color.
The reference value is calculated from the character attribute information, the color difference is compared with the reference value, and the character color is changed as necessary.

That is, the character color converter 40 refers to the character color received from the character background color extractor 30 and the background color, and
The color difference is obtained by the following method. Here, a case where the character color is a, the background color is b, and the colors are represented by RGB will be described.

The RGB components of the character color a are represented by Ra, Ga, B
a, and when the RGB components of the background color b are Rb, Gb, and Bb, the difference between the RGB characters and the background color is represented by Re,
Ge and Be are obtained by the following equations.

Re = Ra−Rb (3) Re = Ga−Gb (4) Be = Ba−Bb (5) Next, the color difference ΔERGB is obtained by the following equation.

ΔERGB = (Re ² + Ge ² + Be ² ) ^1/2 (6) A reference color difference ΔEsd for distinguishing a character from a background is set to 10, and this value is determined by the character attribute information v as follows: to correct. That is, since the character attribute information v is represented in eight levels from 0 to 7, it is corrected by the following equation.

ΔE std = ΔE std + (v−3) × 2 (7) If the color difference ΔE RGB is equal to or greater than ΔE std, no color conversion is performed, and if the color difference ΔE RGB is less than ΔE std, the color conversion is performed. I do. When the background color is "0", no color conversion is performed.

The conversion amount △ E of the color difference ΔERGB is obtained by the following equation. ΔE = (ΔEstd−ΔERGB) / 3 ^1/2 (8) Whether to increase or decrease the value of the character color is determined by the following method. That is, when the following expression is satisfied, the value of the character color is increased because the value of the character color is greater than or equal to the value of the background color.

Re + Ge + Be ≧ 0 (9) On the other hand, when the following expression is satisfied, the value of the character color is reduced because the value of the character color is smaller than the value of the background color.

Re + Ge + Be <0 (10) Here, when the value of the character color is increased, the value of each of the RGB colors is increased by ΔE.

Ra = Ra + ΔE (11) Ga = Ga + ΔE (12) Ba = Ba + ΔE (13) On the other hand, when the value of the character color is to be reduced, the value of each of the RGB colors must be changed. Reduce each by ΔE.

Ra = Ra−ΔE (14) Ga = Ga−ΔE (15) Ba = Ba−ΔE (16) However, the values of Ra, Ga, and Ba exceeded 255. 2 in case
55, and 0 when it becomes a negative value.

Finally, the value of the color information of the edge list corresponding to the character is converted into the values of Ra, Ga, and Ba obtained above. As described above, the edge list whose character color has been converted as necessary is supplied to the bitmap developing unit 50.

The bitmap developing section 50 develops the supplied edge list into a bitmap which is data in a display format. FIG. 13 is a flowchart illustrating an example of a process performed by the bitmap developing unit 50.
When this flowchart is started, the following processing is executed. [S20] The bitmap developing unit 50 secures a memory for storing the generated bitmap image. [S21] The bitmap developing unit 50 checks the y bucket in which the connected cell first exists, and acquires the first connected cell of the y bucket. [S22] The bitmap developing unit 50 determines whether or not the obtained linked cell is a character or graphic. That is, the bitmap developing unit 50 determines whether or not the drawing object determination flag of the acquired connected cell is “00” or “01”. If the flag is “00” or “01”, the process proceeds to step S23. The process proceeds to step S25 otherwise. [S23] The bitmap developing unit 50 acquires a start point, an end point, and color information from the acquired connected cells. [S24] The bitmap developing unit 50 arranges the color information acquired in step S23 in a corresponding part of the memory. [S25] The bitmap developing unit 50 acquires a start point, an end point, and a data address from the acquired connected cells. [S26] The bitmap developing unit 50 determines in step S25
The raster data is read out from the raster data buffer 20d with reference to the data address obtained in the above, and is arranged in a predetermined area of the memory. [S27] The bitmap developing unit 50 determines that the link flag is E
It is determined whether or not it is OC, and if it is EOC, the process proceeds to step S28; otherwise, the process proceeds to step S29.
Proceed to. [S28] The bitmap developing unit 50 determines whether or not there is an unprocessed connected cell. If there is, the process proceeds to step S30; otherwise, the process ends. [S29] The bitmap developing unit 50 acquires the next connected cell, and returns to step S22. [S30] The bitmap developing unit 50 acquires the first connected cell of the next y bucket, and returns to step S22.

According to the above processing, the edge list can be developed into a bit map. FIG. 14 is a diagram illustrating an example where the edge list is developed into a bitmap.

In the example shown in FIG. 14A, connected cells corresponding to characters, figures, and rasters are connected to the first bucket. The bucket corresponding to the first character has a start point of 1, a finish point of 3, and color information of c1 (=
200), as shown in FIG.
200 from the first column to the third column of the scan line
Is arranged.

The bucket corresponding to the second image has a starting point of 4, an ending point of 6, and color information of c2 (= 255). Therefore, as shown in FIG. The value 255 is arranged from the fourth column to the sixth column of the scanning line.

The bucket corresponding to the third image has a starting point of 7, a ending point of 10, and a data address of ad.
Is read from the area having the first address as the first address, and as shown in FIG. 14B, raster data is arranged from the seventh column to the tenth column of the first scan line.

The bitmap data generated as described above is printed out on recording paper by a printer or the like. According to the above embodiment, the character color is changed as necessary by referring to the color difference between the character and the background and the attribute information of the character, so that the font size of the character is small, Even when a thin typeface is used, the legibility of characters can be improved.

In the above embodiment, the character color is changed with reference to the color difference between the character and the background. For example, the character color is changed with reference to the brightness of the character and the background. Is also good. The method is described below.

First, a method for obtaining the brightness of a character and a background will be described. The RGB components of the character color a are represented by L ^* a ^* b ^*
To convert to a color system, first Ra Ga Ba to XaYa
Za is obtained by the following equation.

Xa = 2.7689 × Ra + 1.51717 × Ga + 1.130 × Ba (17) Ya = 1.0000 × Ra + 4.5907 × Ga + 0.0601 × Ba (18) Za = 0.00000 × Ra + 0.0565 × Ga + 5.5943 × Ba (19) Similarly, Xb, Yb, Zb, are obtained from the RGB components Ra, Ga, Ba of the background color b.

Next, the lightness La ^{* of the} character is calculated from Xa Ya Za ^.
Is determined by the following equation. La ^* = 116 × (Ya / 255) ^1/3 −16 (if Ya / 255> 0.008856) (20) La ^* = 903.3 × (Ya / 255) (Ya / 255 ≦ 0) (In the case of .008856) (21) Similarly, the lightness Lb ^{* of} the background is also obtained, and the difference ΔLdiff ^* between the lightness of the character and the background is obtained by the following equation.

ΔLdiff ^* = La ^* −Lb ^* (22) A reference lightness difference ΔLstd ^* that can identify a character and a background is set to 5, and this value is set as follows according to information of a character size and a font type. To be corrected. That is, since the information v of the character size and the font type is represented in eight stages from 0 to 7, it is corrected by the following equation.

ΔLstd^*= △ Lstd^*+ (V−3) × 0.5 (23) Lightness difference ΔLdiff^*Ga Lstd^*In this case, color conversion is performed.
Lightness difference ΔLdiff ^*Ga Lstd^*Color change if less than
Exchange. Conversion amount of lightness difference △ L^*Is determined by the following equation.

ΔL ^* = ΔLstd ^* −ΔLdiff ^* (24) Whether to increase or decrease the character color value is determined by the following method. When the following expression holds, the value of the character color is increased because the value of the character color is greater than or equal to the value of the background color.

.DELTA.Ldiff ^* .gtoreq.0 (25) When the following expression is satisfied, the value of the character color is reduced because the value of the character color is smaller than the value of the background color.

△ Ldiff ^* <0 (26) When the value of the character color is increased, each color of RGB is increased at the following ratio. Ra = Ra + 1.0000 × △ L * (27) Ga = Ga + 4.5907 × △ L * (28) Ba = Ba + 0.0601 × △ L * (29) Character color Is reduced, the RGB colors are reduced at the following ratio.

Ra = Ra−1.0000 × ΔL * (30) Ga = Ga−4.5907 × ΔL * (31) Ba = Ba−0.0601 × ΔL * (32) However, when the values of Ra, Ga, and Ba exceed 255, they are set to 255, and when they become negative, they are set to 0. Next, the values of the color information in the edge list are converted into the values of Ra, Ga, and Ba obtained here.

According to the above method, more natural conversion can be performed as compared with the case where the color difference is used. That is, when color difference is used, the degree of emphasis is large when both the character and background colors are dark, and the degree of emphasis is small when both the character and background colors are light. According to the above method, such inconvenience can be solved.

Next, another embodiment of the present invention will be described. FIG. 15 is a block diagram showing a configuration example of another embodiment of the present invention. In this figure, parts corresponding to those in the case of FIG. 2 are denoted by the same reference numerals, and a description thereof will be omitted.

In the embodiment shown in FIG. 15, a screen processing unit 60 is newly added, and character color conversion unit 40 refers to the size of the screen used in screen processing unit 60 to change the character color. The conversion is performed. Other configurations are the same as those in FIG.

The screen processing section 60 converts the halftone image into two
FIG. 1 shows bit map data for displaying values.
A binarization process is performed using a screen as shown in FIG.

The character color conversion unit 40 converts the character color with reference to not only the character attribute information but also the size of the screen used in the screen processing unit 60. Next, the operation of the above embodiment will be described. In addition,
The operations other than the character color conversion unit 40 and the screen processing unit 60 are the same as those in FIG. 2, and therefore, only the operation of the character color conversion unit 40 and the screen processing unit 60 will be described below.

The character color conversion unit 40 includes the screen processing unit 6
Get screen size from 0. As the size of the screen, for example, m × m (bit) is acquired. The character color conversion unit 40 generates screen size information w from the acquired screen size by the following method.

If m <5, w = 0 if 5 ≦ m <9, w = 1 if 9 ≦ m <13, w = 2 if 13 ≦ m <17, w = 3 if 17 ≦ m, w = 4. When the screen size is given by the screen ruling i, screen size information w is generated by the following method.

If i <100, w = 4 if 100 ≦ i <150, w = 3 if 150 ≦ i <200, w = 2 if 200 ≦ i <250, w = 1 if 300 ≦ i, w = 0 characters The color conversion unit 40 calculates the reference value ΔEstd by substituting the screen size information w and the character attribute information v thus obtained into the following equation.

ΔE std = ΔE std + (v−3) × 2 + (w−2) (33) The reference value ΔE std thus obtained is compared with the color difference ΔE RGB calculated by the equation (6). , Color difference ΔERGB
Is smaller than or equal to the reference value ΔEstd, the character color is not converted. If the color difference ΔERGB is smaller than the reference value ΔEstd, the character color is converted in accordance with the processing from the above equation (8).

When the character color is converted based on the brightness difference, the screen size information w and the character attribute information v
Is substituted into the following equation to obtain the reference value ΔLstd ^*.
Is calculated.

ΔLstd ^* = ΔLstd ^* + (v−3) × 0.5 + (w−2) × 0.25 (34) Then, the lightness difference ΔLdiff ^* obtained by Expression (22) is △
If Lstd ^* or more, no color conversion is performed, and the lightness difference ΔLdiff
^{If *} is less than △ L std ^* , color conversion is performed.

The edge data obtained by converting the character color based on the character attribute and the screen size as described above is supplied to the bitmap developing section 50, where it is developed into bitmap data and then supplied to the screen processing section 60. Is done.

The screen processing unit 60 performs a screen process on the bitmap data shown in FIG. 16A using a screen shown in FIG. 16B (3 × 3 screen in this example).

That is, each bit of the 3 × 3 area of the bitmap data shown in FIG. 16A is compared with each bit of the screen shown in FIG. If the value is equal to or greater than the value, "1" is output, while if the pixel value of the bitmap is less than the pixel value of the screen, "0" is output.

Then, the same processing is performed on all the bitmap data while the screen is appropriately moved while eliminating the overlap, so that the pixel value becomes “0” or “1” as shown in FIG. Is generated.

According to the above-described embodiment, when screen processing is performed on the bitmap data by the screen processing unit 60, the character color is converted with reference to the character attribute information and the screen size information. Therefore, the character color is appropriately converted not only according to the type of font but also according to the size of the screen, so that it is possible to prevent the legibility of the character from deteriorating even when the screen size is large.

In the above embodiment, the character color is converted with reference to the color difference or the lightness difference. However, the present invention is not limited to these, and for example, the density difference is used. It is also possible.

Further, the present invention can be applied not only to a printer but also to a CRT monitor or the like. Further, the above processing functions can be realized by a computer. In this case, the processing contents of the functions that the image processing apparatus should have are described in a program recorded on a computer-readable recording medium, and the above processing is realized by the computer by executing the program on the computer. Is done. Examples of the computer-readable recording medium include a magnetic recording device and a semiconductor memory.

For distribution to the market, a CD-ROM
(Compact Disk Read Only Memory) or a program stored in a portable recording medium such as a floppy disk and distributed, or stored in a storage device of a computer connected via a network and transferred to another computer via the network You can also. When the program is executed by the computer, the program may be stored in a hard disk device or the like in the computer, loaded into the main memory, and executed.

[0136]

As described above, according to the present invention, in an image processing apparatus for converting drawing data including a character into display format data, attribute information of a font corresponding to the character is obtained, and the character and its background are obtained. Calculate the difference between the display parameters related to the degree of discrimination, and change the display parameters of the characters as necessary according to the font attribute information and the difference between the display parameters. Since the drawing data is converted into display format data, it is possible to perform highly legible display irrespective of the font size, type, or font used.

Further, information on the size of the screen is obtained, and the difference between the display parameters relating to the degree of discrimination between the character and its background is calculated.
In accordance with the difference between the display parameters, the display parameters of the characters are changed as necessary, and the characters whose display parameters have been changed and other drawing data are converted into display format data, and the obtained display format is obtained. Is subjected to screen processing, so that highly readable display can be performed regardless of the size of the screen.

[Brief description of the drawings]

FIG. 1 is a principle diagram for explaining the operation principle of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a detailed configuration example of an edge list generation unit illustrated in FIG. 2;

FIG. 4 is a diagram illustrating a configuration example of a display list of characters generated by a display list processing unit.

FIG. 5 is a diagram illustrating a configuration example of a display list of graphics generated by a display list processing unit.

FIG. 6 is a diagram illustrating a configuration example of a raster display list generated by a display list processing unit.

FIG. 7 is a diagram illustrating a configuration example of an edge list generated by an edge list generation unit.

FIG. 8 is a diagram illustrating an example of a display list expanding method.

FIG. 9 is a diagram illustrating an example of a method of generating an edge list from a display list.

FIG. 10 is a diagram illustrating an example of a method of combining a plurality of edge lists.

FIG. 11 is a flowchart illustrating the operation of a character background color extraction unit.

FIG. 12 is a diagram illustrating an example of generating an edge list when a character and a figure overlap;

FIG. 13 is a flowchart for explaining the operation of the bitmap developing unit.

FIG. 14 is a diagram illustrating an example of developing an edge list into a bitmap.

FIG. 15 is a block diagram showing a configuration example of another embodiment of the present invention.

FIG. 16 is a diagram illustrating an example of a screen process.

[Explanation of symbols]

 i1 Data to be processed i2 Bitmap data 1 Font attribute information acquisition means 2 Display parameter difference calculation means 3 Reference value calculation means 4 Display parameter change means 5 Conversion means 10 Print data 20 Edge list generation unit 20a Print data interpretation unit 20b Display list processing Unit 20c raster data processing unit 20d raster data buffer 20e edge list processing unit 30 character background color extraction unit 40 character color conversion unit 50 bitmap development unit 60 screen processing unit

Claims (11)

[Claims] 1. An image processing apparatus for converting drawing data including a character into data in a display format, comprising: font attribute information obtaining means for obtaining font attribute information corresponding to the character; and identifying the character and its background. Display parameter difference calculating means for calculating a difference between display parameters related to the degree; display parameter changing means for changing the display parameter of the character as necessary according to the attribute information of the font and the difference between the display parameters. An image processing apparatus comprising: a conversion unit configured to convert the characters whose display parameters have been changed and other drawing data into display format data. 2. The image processing apparatus according to claim 1, wherein the font attribute information is at least one of a font size, a font type, and a font typeface, or a combination thereof. 3. A display apparatus further comprising: a reference value calculating unit configured to calculate a reference value from the font attribute information, wherein the display parameter changing unit compares the display parameter difference with the reference value to determine the display parameter. 2. The image processing apparatus according to claim 1, wherein the image processing apparatus changes the setting. 4. The image processing apparatus according to claim 1, wherein the difference between the display parameters is calculated based on a color difference between the character and its background. 5. The image processing apparatus according to claim 1, wherein the difference between the display parameters is calculated based on a brightness difference between the character and its background. 6. A computer-readable recording medium storing a program for causing a computer to execute a process of converting drawing data including characters into display format data, the computer comprising: Font attribute information acquiring means for acquiring, display parameter difference calculating means for calculating a difference between display parameters relating to the degree of discrimination between the character and its background, and the character according to the attribute information of the font and the difference between the display parameters. A computer that records a program that functions as: display parameter changing means for changing the display parameters of the display device, if necessary, conversion means for converting the characters whose display parameters have been changed, and other drawing data into display format data. A readable recording medium. 7. An image processing apparatus that converts drawing data including characters into data in a display format and performs a screen process, wherein: a screen size obtaining unit that obtains information on the size of the screen; Display parameter difference calculation means for calculating a difference between display parameters related to the degree of discrimination; display parameters for changing the display parameters of the characters as necessary according to the information on the screen size and the difference between the display parameters. Changing means, converting means for converting the characters whose display parameters have been changed, and other drawing data into data in display format, and performing screen processing on the data in display format obtained by the converting means. An image processing apparatus, comprising: a screen processing means for applying. 8. A display apparatus further comprising: a reference value calculating unit configured to calculate a reference value from information on the screen size, wherein the display parameter changing unit compares the display parameter with a difference between the display parameters and determines the display parameter. The image processing apparatus according to claim 7, wherein the image processing apparatus changes the setting. 9. The image processing apparatus according to claim 7, wherein the difference between the display parameters is calculated based on a color difference between the character and its background. 10. The image processing apparatus according to claim 7, wherein the difference between the display parameters is calculated based on a brightness difference between the character and its background. 11. A computer-readable recording medium having recorded thereon a program for causing a computer to execute a process of performing screen processing after converting drawing data including characters into data in a display format. Screen size obtaining means for obtaining information about the display parameter difference calculating means for calculating the difference between the display parameters related to the degree of identification of the character and its background, according to the information about the screen size and the difference between the display parameters, Display parameter changing means for changing the display parameters of the characters as necessary, conversion means for converting the characters whose display parameters have been changed, and other drawing data into data in a display format, Screen data Screen processing unit, a computer-readable recording medium recording a program to function as which processes.