JP5033747B2 - 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 or completely transparent, in which case the underlying canvas or drawing object is covered with the color value of the canvas whose transparency attribute is opaque. Or, if the brightness attribute is transparent, it is transparent, so there is no need to perform an alpha blend operation process, and there is no need to store a 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 there is a canvas with the above-described transparency attribute being opaque or transparent, it has not been possible to improve 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 an image processing apparatus, an image processing method, and an image processing program for performing image processing for converting a page description language into an intermediate language, a canvas having a transparency attribute is opaque from the beginning in a canvas having a transparency attribute. In the case where they exist continuously, the drawing process could not be performed at high speed and with high memory utilization efficiency.

An image processing apparatus according to claim 1, wherein 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 is converted into an image. a is, transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, otherwise canvas The canvas check unit that determines the actual canvas and the drawing on the canvas determined to be the temporary canvas are directly drawn in the page drawing memory, and the drawing on the canvas determined to be the actual canvas is the transparency on the canvas. The main part is that it has a drawing part that draws by performing alpha blending operation, which is a composition of attributes. And features. 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. Opaque means that the transparency of the canvas is 1.0.

  An image processing apparatus according to a second aspect of the present invention is the image processing apparatus according to the first aspect, wherein when the canvas is described in a nested structure in the page description language, the page description language is stored in the canvas. An intermediate language conversion unit that converts to an intermediate language while maintaining a nested structure is provided, and the drawing unit performs the alpha blending operation based on the intermediate language that maintains the nested structure.

  An image processing apparatus according to a third aspect of the present invention is the image processing apparatus according to the first or second aspect, wherein the page description language is described in an XML (Extended Markup Language) extended format. Features.

5. The image processing method according to claim 4, wherein 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 is converted into an image. a is, transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, otherwise canvas Is drawn as a temporary canvas, the drawing on the canvas determined as the temporary canvas is directly drawn in the page drawing memory, and the drawing on the canvas determined as the real canvas is performed with an alpha blend operation on the canvas. Drawing is the most important feature.

The image processing program of the present invention according to claim 5 is a function for converting a page description language including a drawing object having a transparency attribute into a computer and a canvas having a transparency attribute as a basis for drawing the drawing object into an image. an image processing program for realizing, transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas and temporary canvas The canvas check function for determining whether the canvas is not the real canvas, and the drawing on the canvas determined to be the temporary canvas by the canvas check function are directly drawn in the page drawing memory and determined as the actual canvas. Drawing on the canvas is alpha on the canvas. The most important feature that to achieve a drawing function for drawing performing trend calculation in the computer.

An image processing apparatus according to claim 1, wherein 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 is converted into an image. a is, transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, otherwise canvas The canvas check unit that determines the actual canvas and the drawing on the canvas determined to be the temporary canvas are directly drawn in the page drawing memory, and the drawing on the canvas determined to be the actual canvas is the transparency on the canvas. The main part is that it has a drawing part that draws by performing alpha blending operation, which is a composition of attributes. Therefore, when there are consecutive opaque canvases, the processing for each canvas is omitted, and drawing to the page drawing memory is performed directly. Increased use efficiency.

  An image processing apparatus according to a second aspect of the present invention is the image processing apparatus according to the first aspect, wherein when the canvas is described in a nested structure in the page description language, the page description language is stored in the canvas. Since it has an intermediate language conversion unit that converts to an intermediate language while maintaining a nested structure, the drawing unit is characterized by performing the alpha blending operation based on the intermediate language that maintains the nested structure, In the intermediate language drawn in the nested structure, it is possible to process a continuous opaque canvas by a recursive algorithm.

  An image processing apparatus according to a third aspect of the present invention is the image processing apparatus according to the first or second aspect, wherein the page description language is described in an XML (Extended Markup Language) extended format. Because of the feature, in a page description language such as XPS (XML Paper Specification), it has become possible to process an opaque canvas that is continuous from the beginning at high speed.

5. The image processing method according to claim 4, wherein 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 is converted into an image. a is, transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, otherwise canvas Is drawn as a temporary canvas, the drawing on the canvas determined as the temporary canvas is directly drawn in the page drawing memory, and the drawing on the canvas determined as the real canvas is performed with an alpha blend operation on the canvas. The most important feature is that when there is a continuous opaque canvas, Of omitting to perform the processing for each canvas for drawing directly to the page drawing memory, the image conversion process is faster and increased utilization efficiency of the memory.

5. The image processing method according to claim 4, wherein 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 is converted into an image. a is, transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, otherwise canvas Is drawn as a temporary canvas, the drawing on the canvas determined as the temporary canvas is directly drawn in the page drawing memory, and the drawing on the canvas determined as the real canvas is performed with an alpha blend operation on the canvas. The most important feature is that when there is a continuous opaque canvas, Of omitting to perform the processing for each canvas for drawing directly to the page drawing memory, the image conversion process is faster and increased utilization efficiency of the memory.

  In an image processing apparatus, an image processing method, and an image processing program for performing image processing for converting a page description language into an intermediate language, when an opaque canvas is continuously present from the beginning, the processing is not performed for each canvas. Instead, by drawing directly in the page drawing memory, it is possible to perform conversion processing to a page description language bitmap at high speed and with high memory utilization efficiency.

  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. 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 canvas check unit 1.4.1, and a canvas Functions of memory calculation unit 1.4.3, drawing unit 1.5 (alpha blend operation unit), output unit 1.6, system control unit 1.7, error control unit 1.8, and memory management unit 1.9 Part. 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 can have 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 the 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 canvas check unit 1.4.1 remembers this in units of pages when transparency is set 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. When the canvas check unit 1.4.1 makes an inquiry from the drawing data processing unit 1.4, the canvas check unit 1.4.1 returns information on whether or not there is a transparency setting at that time.

  The canvas memory calculation unit 1.4.3 calculates a memory necessary for holding canvas data.

  The drawing unit 1.5 is a functional unit that creates bitmap data in the VRAM (page drawing memory) 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, if there is a command for setting transparency, the drawing data processing unit 1.4 transmits the content of the command to the canvas check unit 1.4.1. The canvas check unit 1.4.1 confirms and stores whether the transparency setting is completely transparent or whether a transparency other than opaque is designated (hereinafter referred to as translucent). Then, it is stored whether or not a translucent drawing object is actually generated.

  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 canvas check unit 1.4.1 whether or not there is a drawing object in which a translucent transparency 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. When processing the canvas, in the case of a temporary canvas, all the drawing objects are directly bitmapped on the VRAM (page drawing memory). In the case of an actual canvas, as shown in FIGS. 3C and 3D, bitmap processing is performed using canvas memory necessary for blend processing.

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

  FIG. 9 is a flowchart when the canvas is designated in S304 of the flowchart of FIG.

  S401: The canvas check unit 1.4.1 checks whether the transparency setting of the designated canvas is opaque.

  S402: When the designated canvas is opaque, the canvas check unit 1.4.1 confirms whether an opaque canvas is designated continuously from the first canvas.

  S403: If an opaque canvas is specified continuously from the first canvas including the specified canvas, the canvas check unit 1.4.1 indicates that the specified canvas is a temporary canvas. Record in information.

  S404: The canvas check unit 1.4.1 records information that the designated canvas is a real canvas in the canvas information.

  S405: The canvas memory calculation unit 1.4.3 calculates and stores the memory amount necessary for canvas processing.

[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.

  In this image processing device, the canvas that must be actually acquired for canvas processing is determined by determining whether the specified canvas is opaque and the opaque canvas is specified continuously from the first canvas. And the canvas that can be drawn directly (page drawing memory) can be distinguished to improve the memory efficiency and improve the processing speed.

[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. FIG. 9 is a detailed flowchart of “specified processing” in S304 in FIG. 8.

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 Canvas Check Unit 1.4.3 Canvas Memory Calculation Unit 1.5 Drawing Unit (Alpha Blend Calculation Unit)
1.6 Output unit 1.7 System control unit 1.8 Error control unit 1.9 Memory management unit

Claims (5)

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,
Transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is continuous, the continuous canvas is determined that the temporary canvas, determines the actual canvas canvas otherwise A canvas check section to
The drawing on the canvas determined to be the temporary canvas is directly drawn in the page drawing memory, and the drawing on the canvas determined to be the actual canvas is performed by performing an alpha blend operation that is a composition of the transparency attribute on the canvas. An image processing apparatus comprising: a drawing unit for drawing. The image processing apparatus according to claim 1,
An intermediate language conversion unit for converting the page description language into an intermediate language while maintaining the nested structure of the canvas when the canvas is described in a nested structure in the page description language;
The image processing apparatus, wherein the rendering unit performs the alpha blending operation based on an intermediate language that maintains the nested structure. The image processing apparatus according to claim 1 or 2,
The image processing apparatus, wherein the page description language is described in an XML (Extended Markup Language) extended format. An image processing method for 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,
Transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, and the actual canvas canvas otherwise Judgment
Drawing on the canvas determined to be the temporary canvas is directly drawn in a page drawing memory, and drawing on the canvas determined to be the actual canvas is drawn by performing an alpha blend operation on the canvas. Image processing method. 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,
Transparency attributes of the canvas to determine whether opaque, when the canvas where it is determined that not transparent is to continue communication is the continuous canvas is determined that the temporary canvas, and the actual canvas canvas otherwise The canvas check function to judge,
Drawing on the canvas determined as the temporary canvas by the canvas check function is directly drawn in the page drawing memory, and drawing on the canvas determined as the real canvas is performed by performing an alpha blend operation on the canvas. An image processing program for causing a computer to realize a drawing function for drawing.