JP5007291B2 - Image processing apparatus, image processing method, and image processing program - Google Patents

Description

  When bitmap conversion is performed on a page description language that can represent a drawing object having a transparency attribute and a canvas that has a transparency attribute as a basis for drawing the drawing object, the bitmap conversion processing can be performed at high speed. In addition, the present invention relates to a technology for increasing the memory utilization efficiency.

  In a page description language described in an XML extended format such as XPS, a drawing object having a transparency attribute (path, font, image, etc.) and a plurality of canvases having a transparency attribute as a basis for drawing the drawing object It is possible to overlap, and when performing the blending process (alpha blending computation process) of the drawing object and the canvas transparency attribute, which are a plurality of layers, the alpha blending computation process is performed for each layer of the canvas. For this reason, it is necessary to secure a memory and to perform the alpha blend calculation process. However, depending on the canvas, the transparency attribute may be opaque. In this case, the underlying canvas or drawing object is covered with the color value of the opaque canvas, so it is necessary to perform alpha blending processing. There is no need to store memory for each layer of the canvas.

  As a conventional technology, the rendering results differ depending on whether the device is compressed to the device color gamut before the alpha blend calculation processing or the device color gamut and then the alpha blend processing is performed. There is a method of determining a more appropriate method (see Patent Document 1).

However, even in this method, when the transparency attribute of all the canvases described above is opaque, it is not possible to realize the memory efficiency and the processing speed.
JP 2006-345197 A XML Paper Specification, XPS Specification and Reference Guide Version 1.0

  The problem to be solved is that, in the image processing apparatus, the image processing method, and the image processing program for performing the image processing for converting the page description language into the intermediate language, when all the canvases having the transparency attribute are opaque, the bitmap conversion is performed. This is the point that processing could not be performed at high speed and with high memory utilization efficiency.

  An image processing apparatus according to the present invention is an image processing apparatus that converts a page description language including a drawing object having a transparency attribute and a canvas having a transparency attribute serving as a basis for drawing the drawing object into an image. When there is at least one transparent or semi-transparent canvas by the transparency setting monitoring unit for determining the transparency attribute of the canvas and the transparency setting monitoring unit, the storage capacity for alpha blending calculation, which is a combination of transparency attributes, is set. A rendering unit that performs rendering directly on the page rendering memory without securing a storage capacity for the alpha blending operation when all the canvases are determined to be opaque. It is characterized by having.

  Here, the canvas is an object that serves as a basis for drawing objects (paths, fonts, and images) described in the page description language in the XML extension format. The transparency value indicating transparency and the transparency indicating the transparency distribution are also included. It has a transparency attribute such as a mask. Transparent means that the transparency value is 0, opaque means that the transparency value is 1.0, and translucency means that the transparency value is between 0 and 1.0.

  The image processing apparatus of the present invention may be characterized in that the page description language is described in an XML (Extended Markup Language) extended format.

An image processing method according to the present invention includes a transparency setting monitoring unit, a rendering unit, a rendering object having a transparency attribute, and a page description language including a canvas having a transparency attribute that serves as a basis for rendering the rendering object An image processing method using an image processing apparatus for converting an image into an image , wherein a transparency attribute of the canvas is determined by the transparency setting monitoring unit, and the transparency attribute is transparent or translucent by the transparency setting monitoring unit If but it is determined that there is at least 1, to ensure the storage capacity for the alpha blending operation is the synthesis of transparency attribute by the drawing unit performs the alpha blending operation, all by the transparency setting monitoring unit storage capacity for when the canvas is determined to opaque, the alpha blending operation by the drawing unit And performing a drawing directly to page drawing memory without allocating a.

  An image processing program according to the present invention realizes a function of converting a page description language including a drawing object having a transparency attribute and a canvas having a transparency attribute as a basis for drawing the drawing object into an image on a computer. When there is at least one transparent or semi-transparent canvas by the transparency setting monitoring function for judging the transparency attribute of the canvas and the transparency setting monitoring function, an alpha blending operation that is a combination of the transparency attributes When the alpha blending operation is performed while securing the storage capacity for all of the canvases and it is determined that all the canvases are opaque, the storage capacity for the alpha blending operation is not secured and the page drawing memory is directly reserved. A computer that realizes a drawing function for drawing

  An image processing apparatus according to the present invention is an image processing apparatus that converts a page description language including a drawing object having a transparency attribute and a canvas having a transparency attribute serving as a basis for drawing the drawing object into an image. When there is at least one transparent or semi-transparent canvas by the transparency setting monitoring unit for determining the transparency attribute of the canvas and the transparency setting monitoring unit, the storage capacity for alpha blending calculation, which is a combination of transparency attributes, is set. A rendering unit that performs rendering directly on the page rendering memory without securing a storage capacity for the alpha blending operation when all the canvases are determined to be opaque. It is characterized by having.

  For this reason, when performing an alpha blending operation for composition of transparency attributes, if all canvases are opaque, drawing is performed directly in the drawing memory without performing the alpha blending operation and maintaining the storage capacity therefor. Therefore, it is possible to perform conversion processing to an image of a page description language at high speed and with high memory utilization efficiency.

  The image processing apparatus of the present invention may be characterized in that the page description language is described in an XML (Extended Markup Language) extended format.

  For this reason, it has become possible to perform image conversion processing to a page description language bitmap or the like described in an XML extension format such as XPS (XML Paper Specification) at high speed and with high memory utilization efficiency.

An image processing method according to the present invention includes a transparency setting monitoring unit, a rendering unit, a rendering object having a transparency attribute, and a page description language including a canvas having a transparency attribute that serves as a basis for rendering the rendering object An image processing method using an image processing apparatus for converting an image into an image , wherein a transparency attribute of the canvas is determined by the transparency setting monitoring unit, and the transparency attribute is transparent or translucent by the transparency setting monitoring unit If but it is determined that there is at least 1, to ensure the storage capacity for the alpha blending operation is the synthesis of transparency attribute by the drawing unit performs the alpha blending operation, all by the transparency setting monitoring unit storage capacity for when the canvas is determined to opaque, the alpha blending operation by the drawing unit And performing a drawing directly to page drawing memory without allocating a.

  For this reason, when performing an alpha blending operation for composition of transparency attributes, if all canvases are opaque, drawing is performed directly in the drawing memory without performing the alpha blending operation and maintaining the storage capacity therefor. Therefore, it is possible to perform conversion processing to an image of a page description language at high speed and with high memory utilization efficiency.

  An image processing program according to the present invention realizes a function of converting a page description language including a drawing object having a transparency attribute and a canvas having a transparency attribute as a basis for drawing the drawing object into an image on a computer. When there is at least one transparent or semi-transparent canvas by the transparency setting monitoring function for judging the transparency attribute of the canvas and the transparency setting monitoring function, an alpha blending operation that is a combination of the transparency attributes When the alpha blending operation is performed while securing the storage capacity for all of the canvases and it is determined that all the canvases are opaque, the storage capacity for the alpha blending operation is not secured and the page drawing memory is directly reserved. A computer that realizes a drawing function for drawing

  For this reason, when performing an alpha blending operation for composition of transparency attributes, if all canvases are opaque, drawing is performed directly in the drawing memory without performing the alpha blending operation and maintaining the storage capacity therefor. Therefore, it is possible to perform conversion processing to an image of a page description language at high speed and with high memory utilization efficiency.

  In the image processing device, image processing method, and image processing program for performing image processing for converting the page description language into an intermediate language, when performing the alpha blend operation for canvases having transparency attributes, the transparency attributes of all canvases are opaque Does not secure the memory capacity to hold the attributes of transparency and transparency mask, and omits the alpha blend operation and renders directly to the page rendering memory, thereby converting the page description language into a bitmap. It has become possible to increase the memory utilization efficiency at high speed.

  An image processing apparatus according to an embodiment of the present invention will be described below.

[Synthesis of transparency attributes; alpha blending]
Alpha blending is a semi-transparent composition of two images each having a color value using a certain coefficient. This coefficient is called an alpha value and takes a value of 0.0 to 1.0. 0.0 indicates completely transparent, 1.0 indicates completely opaque overlay. The value in between is translucent overlay. In the PDF (Portable Document Format) and XPS (XML Paper Specification) document formats, alpha values can be set for objects such as path figures, fonts, and images. Synthesis of transparency and color values).

  The following explains how alpha blend transparency synthesis processing is performed using XPS document format data as an example.

Figure 1 shows the path data with transparency attribute expressed in XPS, and the steps for strictly performing alpha blending described in 11.4 Opacity Computations of XPS specification 1.0 (see Non-Patent Document 1) are as follows: Show.
(1): The alpha value on the source side is obtained. Multiply the alpha value of the source by the value of the Opacity attribute and the value of OpacityMask.

As1 = As * Oe * Om
As: Source element alpha value (see Figure 1)
Oe: Opacity value of the source element (see Fig. 1)
Om: OpacityMask value of the source element at the pixel position to draw (see Figure 1)
(2): The alpha value (As1) obtained in (1) is applied to the source color value. This process is called Pre-multiply source alpha. Cs in the following expression is a value for each plane in the current color space such as RGB, Gray, or CMYK.

Cs_tmp = Cs * As1
Cs: Source color value (see Figure 1)
Cs_tmp: Temporary value of source side color value (3): Multiply destination side alpha by destination color value. This process is called Pre-multiply destination alpha. The destination pixel color value Cd in the following expression is a value for each plane in the current color space such as RGB, Gray, and CMYK, as in the source side.

Cd_tmp = Cd * Ad
Ad: Alpha value of the destination
Cd: Destination drawing pixel position color value
Cd_tmp: Temporary destination color value (4): Blend processing is performed.

A_tmp = (1-As1) * Ad + As1
C_tmp = (1-As1) * Cd_tmp + Cs_tmp
A_tmp: Temporary for checking (5)
C_tmp: Temporary for checking in (5) (5): A value to be written to the destination result is obtained. This process is called Reverse pre-multiplication.

If A_tmp = 0
{
Anew = Cnew = 0
}
Else
{
Anew = A_tmp
Cnew = min (C_tmp / A_tmp, 1)
}
The parameters appearing in (1) and (2) appear in the XPS document of FIG. 1 (see Non-Patent Document 1 for more details).

[Case of drawing on page]
In the blend processing step (3), the background is opaque in the drawing process on the page, that is, Ad = 1.0. In this case, as described below, the alpha blend process can be performed using only the source color value and alpha value and the destination color value already written on the page (see FIG. 2A).

As1 = As * Oe * Om
Anew = 1.0 (Opaque and unchanged)
Cnew = (1-As1) Cd + As1 * Cs (known as a simple alpha blend formula)
[If the canvas has no transparency attribute]
In the blend processing step (3), in the drawing process on the canvas, in the initial state, the background is completely transparent, Ad = 0.0, no color, and Cd = 0.0 (RGB if black). This is the image of a glass plate.

As1 = As * Oe * Om
Anew = As1 (accumulated alpha value)
Cnew = Cs (the source color value remains the same)
If nothing is drawn on the canvas and the blending step is followed, as shown above, if the object on the canvas contains transparency, the color value and alpha value are accumulated on the canvas as they are. Will be. This indicates that the accumulated value affects the source alpha value when the canvas is drawn on a layer below the page or the like.

However, when transparency is not set on the canvas itself, the result of drawing the completed canvas on the page is the same as when the object is directly written on the page (see FIG. 2B).
In this case, it is not necessary to perform drawing in a buffer different from the page as shown in FIG. 2B, and the same processing as when the canvas is not defined may be performed.

[If the canvas has a transparency attribute]
As described above, the color value and the alpha value accumulate in the area where the object is drawn, but the other areas remain completely transparent at 0.0.

  Regarding the rendering method when transparency is set on the canvas itself, in the implementation method presented in the XPS specification, when the object drawing on the canvas is finished and written to the lower layer, the Opacity attribute of the canvas element And apply (combine) the values of OpacityMask to the accumulated alpha value. This means that in the blending step (1), Oe and Om of the canvas itself are multiplied by the accumulated alpha value.

  In addition, even if Opacity and OpacityMask are applied, the area where no object is drawn in the canvas remains in the state where alpha value is 0.0 and nothing is completely transparent. For this reason, the effect of the transparency processing is exerted only on the portion of the drawn object (see FIG. 3C).

  Conceptually, the steps described above are performed, but if the same processing is performed on the same canvas, if the objects overlap, the strict blending process of FIG. 2A taking into account the alpha value of the destination (FIG. 3D).

[Constitution]
FIG. 4 is a functional block diagram of the image processing apparatus according to the embodiment of the present invention.

  The image processing apparatus includes a communication interface 1.1, a data reception unit 1.2, a data analysis unit 1.3, a drawing data processing unit 1.4 (intermediate language conversion unit), a transparency setting monitoring unit 1.4.1, a drawing Unit 1.5, output unit 1.6, system control unit 1.7, error control unit 1.8, and memory management unit 1.9. Each functional unit will be described below.

  The communication interface 1.1 is a functional unit that performs communication with a host computer or the like.

  The data receiving unit 1.2 is a functional unit that receives data (print data written in a page description language) via the communication interface 1.1.

  The data analysis unit 1.3 is a functional unit that analyzes print data described in the page description language that has been sent.

  The drawing data processing unit 1.4 (intermediate language conversion unit) converts the page description language into an intermediate language (here, specifically, a display list) in accordance with an instruction from the data analysis unit 1.4.

  In a page description language written in an XML extension format such as XPS, there are drawing objects such as paths, glyphs (fonts), images, etc., and there is a canvas that serves as the basis for displaying these drawing objects. . Each of these elements and canvases has a transparency attribute. Also, the canvas has a nested structure (nested structure), and the canvas and elements contained therein can be handled as one group.

  The drawing data processing unit 1.4 is configured to keep the nested structure when converting the canvas data having the nested structure into an intermediate language. FIG. 5 shows a data structure when one canvas object is converted into a display list.

  The canvas object is followed by a “Start” mark that indicates its start, a display list of drawing objects or canvas objects that exist on the canvas, an “End” mark that indicates the end of the canvas, and then the canvas transparency information. End with the “Write” command, which indicates the drawing to the lower layer.

  When the canvas has a nested structure, a pointer to the canvas object to be nested is inserted between the “Start” mark and the “End” mark.

  The transparency setting monitoring unit 1.4.1 remembers this in units of pages when there is a transparency setting in the drawing data entering the drawing data processing unit 1.4. The transparency setting includes the transparency of the canvas, the transparency of the color of the drawing object, OpacityMask, and the like. Also, the transparency setting monitoring unit 1.4.1 returns information on whether or not there is a transparency setting at the time when the drawing data processing unit 1.4 makes an inquiry.

  The drawing unit 1.5 is a functional unit that creates bitmap data in the VRAM from the display list (intermediate language) created by the drawing data processing unit 1.4. Alpha blending calculation processing is performed in the drawing unit 1.5.

  The output unit 1.6 is a functional unit that outputs bitmap data obtained by performing image processing in each functional unit described above. The output may be printing on a recording medium such as paper or a method of performing display output on a display device.

  The system control unit 1.7 is a functional unit that manages common information of the image processing apparatus system and controls the system.

  The error control unit 1.8 is a functional unit that controls processing when an error occurs in the image processing apparatus.

  The memory management unit 1.9 is a functional unit that manages the memory of the system of the image processing apparatus.

[Alpha blending algorithm]
The alpha blend operation of the display list (intermediate language) having the nested structure shown in FIG. 5 is efficiently calculated by the recursive algorithm shown below.

  Considering the calculation composite for a single canvas, the calculation is as follows:

*** _ n represents the number of objects included in the canvas and represents the value of the calculation process.
[Algorithm description by pseudo code]
C = Composite (C_0, O_0)
Input C_0: Current color of the canvas drawing destination
O_0: Entire object included in canvas Output C: Color value of canvas {
S_0 = C_0 (Formula 1)
Repeat the following process for all objects (i from 1 to n).

{
If Obj_i is a canvas, recursive call {
C_i = Composite (SC_ (i-1), Obj_i) (Formula 2)
} Otherwise {
C_i = Obj_i_Color (Formula 3)
}
S_i = (1-Obj_i_Alpha) * SC_ (i-1) + Obj_i_Alpha * C_i (Formula 4)
}
C = S_i
} [End algorithm]
In other words, when the canvas is started, an area where the colors drawn so far are copied (Formula 1), and when the canvas is finished, the alpha value of the canvas itself is used for blending with the ground (Formula 4). . It is only necessary that the initial value S_0 is white at the start of the page.

[Specific example of processing contents]
Specific examples of processing contents of the recursive algorithm described above will be described below with reference to FIGS.

  The algorithm secures a buffer that temporarily holds colors at the start of the canvas, and performs drawing processing in the buffer. This is a method of drawing the buffer as an image at the end of the canvas while blending the next lower layer. If there is further nesting during drawing on the canvas, a recursive call is made, a buffer for holding the color is secured accordingly, and the canvas is processed as an upper level canvas.

  As an example of performing this process, consider a case where semi-transparent canvases are nested (nested), and semi-transparent objects overlap on the canvas.

  In FIG. 6E, a rectangular Object1 that is a drawing object exists on a Canvas1 having Opacity = 0.5 in the first stage expressed in XPS, and a second-stage Canvas2 having Opacity = 0.5 is nested. The triangle Object2 and Object3 exist on the second level of Canvas2.

  Fig. 6 (F) shows the drawing when all the XPS objects are assumed to have no transparency (Opacity), and Fig. 6 (G) shows the alpha blending calculation of transparency (Opacity) as described in XPS. The drawing is shown. However, since color notation is not possible, the drawing is converted to gray scale.

  The processing procedure for the data by the drawing unit 1.5 is shown in FIG. 7 and will be described in comparison with the expression of the recursive algorithm.

[Securing the page buffer]; FIG.
Allocate a page buffer that is the last page to be drawn first.

[Start Canvas1]; FIG. 7 (I)
Copy the result drawn in the page buffer so far to Canvas1 (Formula 1). Furthermore, Object1 on Canvas1 is drawn. (Formulas 3-4). The transparency information of Canvas1 is held in some form (for example, a local variable of a recursive call routine).

[Start Canvas2]; Fig. 7 (J)
Copy the result drawn on Canvas1 to Canvas2 (recursive call with expression 2 and expression 1).

  Next, the objects (Object2, Object3) on Canvas2 are drawn. At this time, alpha blend calculation processing is performed on Canvas2 (Equations 3-4).

  Similarly, the transparency information of Canvas2 is held in some form (for example, a local variable of a recursive call routine).

[End of Canvas2]; Fig. 7 (K)
With Canvas2 itself transparency information (element Opacity value, OpacityMask value), Canvas2 is rendered as an image in Canvas1 (Step 4).

  Free the Canvas2 buffer.

[End of Canvas1]; Fig. 7 (L)
Draw Canvas1 as an image on the page using the transparency attribute information of the Canvas1 itself (Opacity value and OpacityMask value of the element) (Formula 4).

  Free the Canvas1 buffer.

  With the series of operations described above, alpha blending processing can be performed by a recursive algorithm.

[flowchart]
FIG. 8 is a flowchart of the operation of the image processing apparatus according to the embodiment of the present invention.

  S301: When a print command is transmitted from a PC or the like, it is received by the data receiving unit 1.2 via the communication interface 1.1.

  S302: The data received by the data receiving unit 1.2 is analyzed by the data analyzing unit 1.3. The data analysis unit 1.3 performs drawing processing using the drawing data processing unit 1.4.

  S303: It is determined whether the instruction analyzed by the data analysis unit 1.3 is a page output instruction.

  S304: If the command analyzed by the data analysis unit 1.3 is not a page output command, the drawing data processing unit 1.4 performs processing according to the command. The drawing data processing unit 1.4 generates a display list (an intermediate language drawing command) based on the information given from the data analysis unit 1.3. At this time, when there is a command for setting transparency, the drawing data processing unit 1.4 transmits the content of the command to the transparency setting monitoring unit 1.4.1. The transparency setting monitoring unit 1.4.1 determines whether the canvas is opaque from the transparency value of the canvas, and records the result in a flag.

  S305: The data analysis unit 1.3 determines whether all the data received by the data reception unit 1.2 has been processed. If there is still data to be processed, the process returns to S302 for analysis.

  S306: When all the data received by the data receiving unit 1.2 has been processed, an end process is performed. The memory that is no longer needed for the drawing process is released, or the drawing process is completed to the engine.

  S307: The drawing data processing unit 1.4 inquires of the transparency setting monitoring unit 1.4.1 whether there is a drawing object in which the translucency is set in the currently processed page. Then, the information is transmitted to the drawing unit 1.5.

  S308: The drawing data processing unit 1.4 transmits a page output command to the drawing unit 1.5.

  S309: The drawing unit 1.5 optimally performs a process of converting the display list into a bitmap based on the information in S307 and S308. In step S304, the flag value recorded by the transparency setting monitoring unit 1.4.1 is checked. If there is even one non-opaque canvas, a memory for the alpha blending operation is secured, and the alpha blending operation that is the transparency computation is performed. I do. If all canvases are opaque, no alpha blending operation is required and all drawing is performed directly to VRAM (page drawing memory).

  S310: The drawing unit 1.5 sends the completed one-page bitmap to the output unit 1.6 to perform printing.

[Effect of Example]
The image processing apparatus according to the embodiment of the present invention enables the following.

  When converting a page description language to an intermediate language for efficient synthesis (alpha blend operation) of drawing objects with a nested structure described in a page description language such as XPS and other XML extension formats, canvas transparency attributes Conversion was performed while maintaining the nested structure. Furthermore, the alpha blend operation of the intermediate language data having the nested structure is realized by a recursive algorithm.

  The above method makes it possible to efficiently perform alpha blending operations across nested structures.

  Using an intermediate language having the above structure, alpha blending calculation processing is performed, and then conversion to bitmap data is performed to enable printing processing on a printer.

  This image processing device analyzes the transparency setting in the print data and performs bitmap processing of the display list (intermediate language), thereby rendering the memory efficiently and at high speed in specific cases such as when there is no transparency setting. Processing became possible.

[Others]
In the embodiment, the color values are based on the three primary colors of RGB. However, the color values may be CMYK color values, and an alpha blend operation is possible in the same manner.

This is a notation example of alpha value, color value, transparency and transparency mask by XPS. It is a conceptual diagram of the alpha blend (no transparency setting) at the time of the drawing on a canvas. It is a conceptual diagram of the alpha blend (with transparency setting) at the time of the drawing on a canvas. 1 is a functional block diagram of an image processing apparatus according to an embodiment of the present invention. It is an example of the data structure of the display list of the Example of this invention. A notation example (E) of a nested canvas in XPS and its corresponding drawing (with transparency setting (F) and without (G)). It is a figure which shows the process sequence of the drawing of XPS data described in FIG.6 (E). 3 is a flowchart of the operation of the image processing apparatus according to the embodiment of the present invention.

Explanation of symbols

1.1 Communication interface 1.2 Data receiver 1.3 Data analyzer 1.4 Drawing data processor (intermediate language converter)
1.4.1 Transparency setting monitoring unit 1.5 Drawing unit 1.6 Output unit 1.7 System control unit 1.8 Error control unit 1.9 Memory management unit

Claims (4)

An image processing apparatus that converts a page description language including a drawing object having a transparency attribute and a canvas having a transparency attribute serving as a basis for drawing the drawing object into an image,
A transparency setting monitoring unit for determining the transparency attribute of the canvas;
When there is at least one transparent or semi-transparent canvas by the transparency setting monitoring unit, the alpha blending operation is performed by securing a storage capacity for the alpha blending operation, which is a composition of transparency attributes, and all canvases And a rendering unit that performs rendering directly on the page rendering memory without securing a storage capacity for the alpha blending operation. The image processing apparatus according to claim 1,
The image processing apparatus, wherein the page description language is described in an XML (Extended Markup Language) extended format. Image processing for converting a page description language, which includes a transparency setting monitoring unit and a rendering unit, including a rendering object having a transparency attribute, and a canvas having a transparency attribute serving as a basis for rendering the rendering object into an image An image processing method using an apparatus ,
Determining the transparency attribute of the canvas by the transparency setting monitoring unit ;
When the transparency setting monitoring unit determines that there is at least one canvas whose transparency attribute is transparent or translucent, the rendering unit secures a storage capacity for alpha blending calculation, which is a combination of transparency attributes When the alpha blending calculation is performed and all the canvases are determined to be opaque by the transparency setting monitoring unit , the drawing unit does not secure a storage capacity for the alpha blending calculation and directly stores the page drawing memory. An image processing method characterized by performing drawing on the image. An image processing program for realizing a function of converting a page description language into an image including a drawing object having a transparency attribute and a canvas having a transparency attribute serving as a basis for drawing the drawing object on a computer,
A transparency setting monitoring function for determining the transparency attribute of the canvas;
When there is at least one transparent or translucent canvas by the transparency setting monitoring function, all the canvases are obtained by securing the storage capacity for the alpha blend calculation that is a composition of transparency attributes and performing the alpha blend calculation. An image processing program for causing a computer to realize a rendering function for directly rendering a page rendering memory without securing a storage capacity for the alpha blending operation .