JP7380335B2 - Image processing device - Google Patents

Description

The present invention relates to an image processing device that draws image data based on an object described in a document file.

Image data (raster data) may be generated based on the file description. When drawing each page of one file, the same image may be drawn multiple times. For example, a company logo may be placed on each page. Generated image data may be cached to avoid having to generate the same image multiple times during rasterization. An example of a technique for caching images that appear repeatedly when rasterizing based on a file description is described in Patent Document 1.

Specifically, Patent Document 1 discloses that command information for outputting an image to be formed and output is received from a processing execution control device, image information included in a plurality of objects constituting the command information is compared, Detecting a duplicate image information object in which the image information overlaps among the plurality of objects having different identification information for identifying the images, generating drawing information to be referred to when outputting the image based on command information, and generating the drawing information when the image information is drawn. An image forming output control device is described that stores drawing result information that is a result of the detection, and generates the drawing information using the drawing result information of the image information included in the detected duplicate image information object. Attempting to apply cached image data to parts of objects with different identification information.

JP2018-058297A

PDF (Portable Document Format) is a format that allows similar images to be drawn regardless of the environment. In a PDF file, drawing contents are described according to predetermined rules. PDF is widely used.

Components in a PDF file are called objects. Further, a group of objects to which a number (label) is attached is sometimes referred to as an indirect object. Image data for each page can be generated by performing drawing processing (rasterization processing) based on the description of the PDF file. In recent years, there are also image forming apparatuses that analyze and draw (rasterize) a received PDF file. That is, there are image forming apparatuses that can directly process PDF files.

Some objects are intended to be called (executed) multiple times on the same page or in the same job. Repeating the same drawing process (rasterization process) for each call is inefficient. Therefore, the drawing results (image data obtained through rasterization processing) of objects that are repeatedly called may be cached. That is, RIP image data may be cached. When re-executing an object corresponding to cached image data, drawing processing is omitted and the cached image data is reused. Processing can be sped up.

However, caching image data poses a problem in that the memory capacity required for caching may increase. Therefore, the capacity of the installed memory must be increased, making it impossible to reduce the manufacturing cost of the device. Also, cached image data may be processed and used. There is also a problem in that when image data that is a drawing result is processed such as enlargement or rotation, the image quality may noticeably deteriorate.

Note that the apparatus described in Patent Document 1 caches drawing result information, that is, image data. The amount of memory required for the cache may be large. Therefore, the technique described in Patent Document 1 includes the above problem.

In view of the above problems, the present invention caches data that has been converted so that objects that are repeatedly used can be processed at high speed instead of image data, thereby reducing the memory capacity required for the cache.

An image processing device according to the present invention includes a memory and a control section. Memory caches data. The control unit draws image data of each page of the document file based on objects described in the document file. When executing for the first time a specific content stream that is a content stream of a predetermined specific object among the objects included in the document file, the control unit may cause a description of an operator included in the specific content stream to correspond to the operator. Generate conversion data replaced with the start address of the function. The control unit caches the generated conversion data in the memory. In the second and subsequent executions of the specific content stream, the control unit executes and draws the converted data cached in the memory instead of the specific content stream.

According to the present invention, it is possible to cache data that has been converted so that the contents of objects that are repeatedly used can be processed at high speed. The memory capacity required for cache can be reduced.

FIG. 1 is a diagram illustrating an example of an image processing device according to an embodiment. FIG. 3 is a diagram illustrating an example of the flow of a job based on a document file in the image processing apparatus according to the embodiment. FIG. 3 is a diagram showing an example of a content stream. FIG. 3 is a diagram illustrating an example of content stream processing according to the embodiment. FIG. 3 is a diagram illustrating an example of processing when a specific object is executed according to the embodiment. FIG. 3 is a diagram illustrating an example of conversion data generation processing according to the embodiment. FIG. 3 is a diagram illustrating an example of a specific content stream and its converted data. FIG. 7 is a diagram illustrating an example of the advantage of drawing using conversion data according to the embodiment.

An example of an image processing apparatus 100 according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 8. The elements such as the configuration and arrangement described in the description of this embodiment do not limit the scope of the invention and are merely illustrative examples.

(Image processing device 100)
An example of an image processing apparatus 100 according to an embodiment will be described using FIG. 1. FIG. 1 is a diagram illustrating an example of an image processing apparatus 100 according to an embodiment.

As shown in FIG. 1, an image processing apparatus 100 can communicate with a computer 200. For example, computer 200 is a PC. Computer 200 may be a mobile communication device such as a smartphone. The computer 200 and the image processing device 100 can communicate wirelessly or by wire. A plurality of computers 200 can be connected to the image processing apparatus 100.

The image processing device 100 is also an image forming device. The image processing device 100 is a so-called multifunction device. Note that the image processing device 100 may be a printing device other than a multifunction device (for example, a printer). Computer 200 can send files to image processing device 100. The image processing device 100 prints based on the file from the computer 200.

Image processing apparatus 100 includes a control section 1 , a storage section 2 , a document reading section 3 , an operation panel 4 , and a printer section 5 . A control section 1 controls each section. The control section 1 includes a control circuit 10, an image processing circuit 11, and a communication circuit section 12. For example, the control circuit 10 is a CPU. The control circuit 10 performs calculations and processing related to control. For example, the image processing circuit 11 is an ASIC. The image processing circuit 11 performs image processing on the image data of each page and generates output image data for each page. The output image data is image data indicating whether or not toner is to be applied.

The communication circuit section 12 includes a communication control circuit and a communication memory. The communication memory stores communication software. The communication circuit section 12 communicates with the computer 200 according to instructions from the control section 1. The storage unit 2 includes a ROM 21 and a memory 22 (RAM). The storage unit 2 stores control programs and various data. The storage unit 2 may include storage. The storage is a large capacity storage device such as an HDD or SSD.

The document reading section 3 includes a lamp and an image sensor. The lamp irradiates light onto the original to be read. The image sensor receives reflected light from the original and reads the original. The control unit 1 performs A/D conversion on an analog image signal output by the image sensor. The control section 1 generates image data of a document based on the reading by the document reading section 3.

Image processing device 100 includes operation panel 4 . The operation panel 4 includes a display panel 41, a touch panel 42, and hard keys 43. The control unit 1 controls the display on the display panel 41. The control unit 1 causes the display panel 41 to display a screen and an image. Based on the outputs of the touch panel 42 and the hard keys 43, the control unit 1 recognizes the user's settings.

The printer section 5 includes a paper feed section 5a, a paper transport section 5b, an image forming section 5c, and a fixing section 5d. The control section 1 controls the operations of the paper feeding section 5a, the paper transport section 5b, the image forming section 5c, and the fixing section 5d. The paper feed section 5a stores paper. The paper feed section 5a includes a paper feed roller and a paper feed motor. The paper feed motor rotates the paper feed roller. During a print job, the control unit 1 rotates a paper feed motor (paper feed roller). As a result, paper is fed from the paper feed section 5a. The paper transport section 5b includes a pair of transport rollers and a transport motor for transporting the paper. The transport roller pair transports the paper. The conveyance motor rotates a pair of conveyance rollers. During a print job, the control unit 1 causes the paper transport unit 5b to transport the paper.

The image forming section 5c includes a photosensitive drum, a charging device, an exposure device, a developing device, and a transfer roller. Based on the output image data, the control section 1 causes the image forming section 5c to form a toner image. The control unit 1 causes a transfer roller to transfer the formed toner image onto a conveyance sheet. The fixing unit 5d includes a heater, a heating rotor, a pressure rotor, and a fixing motor. The heater heats the heating rotating body. The paper passes through a nip between a heating rotor and a pressure rotor. This fixes the toner image on the paper. During a print job, the control section 1 causes the fixing section 5d to fix the toner image. The paper transport section 5b discharges the printed paper to the outside of the machine.

(Job based on document file)
Next, an example of the flow of a job based on a document file in the image processing apparatus 100 according to the embodiment will be described using FIG. 2. FIG. 2 is a diagram illustrating an example of the flow of a job based on a document file in the image processing apparatus 100 according to the embodiment.

The image processing device 100 can be caused to perform a print job. Based on the image data, the image processing apparatus 100 performs a print job. For example, the image processing apparatus 100 can perform a print job based on the document file received by the communication circuit unit 12. The document file in this description is, for example, a PDF file 6. PDF is an abbreviation for Portable Document Format. The PDF file 6 is a file (data) generated in accordance with the PDF file format. Note that the control circuit 10 of the image processing apparatus 100 can also generate the PDF file 6 based on image data obtained by reading a document.

A PDF file 6 to be printed can be transmitted from the computer 200 to the image processing device 100 (communication circuit section 12). When receiving the PDF file 6, the control unit 1 starts a print job based on the PDF file 6. Further, the PDF file 6 can also be stored in the storage unit 2 (storage) in a non-volatile manner. Then, from among the PDF files 6 stored in the storage unit 2, the PDF file 6 used for the print job can be selected using the operation panel 4. In this case, the control unit 1 starts a print job based on the selected PDF file 6. The start in FIG. 2 is the point in time when a print job is initiated based on the PDF file 6 upon receipt or selection.

The control unit 1 stores the PDF file 6 used for printing in the memory 22 (RAM) (step #11, see FIG. 1). To start generating image data (drawing, rasterization), it is necessary to store the entire PDF file 6 in the memory 22. After storing the PDF file 6 in the memory 22, the control unit 1 performs predetermined processing in accordance with the PDF standards (rules) (step #12). For example, the control unit 1 performs processing such as referencing the trailer included in the PDF file 6, recognizing the start position of the cross-reference table, and referencing the cross-reference table.

Then, the control unit 1 (control circuit 10) starts drawing (rasterization processing) the image data of each page based on the description of the PDF file 6 (Step #13). The control unit 1 performs drawing processing to generate, for example, image data in bitmap format.

The description of the PDF file 6 includes a plurality of objects. An object of the PDF file 6 is a component of the file. Types of objects include boolean (true/false value), null, numbers, character strings, names, arrays, dictionaries, streams, operators, and the like.

Further, the PDF file 6 includes an indirect object as a type of object. An indirect object is an object with an object ID (number, label). An indirect object attached with an object ID can be referenced (quoted) by other objects. An indirect object includes multiple objects (values). The format of the beginning part of the indirect object is "n m obj" (see FIGS. 3 and 7). n is an object number and is a positive integer. m is called a generation number and is a non-negative integer. For example, the first indirect object is described as "1 0 obj". The format of the end of the indirect object is "endobj".

Based on the description, the control unit 1 ends the drawing (rasterization process) of each page included in the PDF file 6 (step #14). The control unit 1 performs image processing on the drawing results (image data of each page) and generates output image data (step #15). Based on the output image data, the control unit 1 causes the printer unit 5 to print (step #16→end). Note that printing may be started before drawing of all pages of the PDF file 6 is completed.

(Processing of content stream CS1)
Next, an example of processing of the content stream CS1 in the image processing apparatus 100 according to the embodiment will be described using FIGS. 3 and 4. FIG. 3 is a diagram showing an example of the content stream CS1. FIG. 4 is a diagram illustrating an example of processing of the content stream CS1 in the image processing apparatus 100 according to the embodiment.

The PDF file 6 includes a description called content stream CS1. Content stream CS1 is an object containing information for drawing image data of each page. Content stream CS1 includes, for example, moving coordinates, changing line thickness, changing color, drawing path, drawing line, drawing fill, drawing font, drawing image, drawing form, drawing transparent group. Contains a description for performing.

Usually, the content stream CS1 is data in text format. Content stream CS1 includes descriptions (objects) called operators. The operator is a command for expressing (drawing) the image data of each page. Operators are written in text format. For example, content stream CS1 includes multiple operators.

FIG. 3 shows an example of content stream CS1. stream means the beginning of content stream CS1. endstream means the end of content stream CS1. In the content stream CS1 shown in FIG. 3, "rg", "re", and "f" are operators. The word meaning operator is predetermined. Incidentally, "rg" is an operator that sets RGB colors for filling. "re" is an operator that adds a rectangular path. "f" is an operator that executes path filling drawing.

RGB (1, 0, 0) in FIG. 3 means red. According to the content stream CS1 in FIG. 3, the control unit 1 (control circuit 10) sets the color to red, and sets a rectangular path with a width of 50 and a height of 50 from the point (0, 0). Draws to fill the path in red.

An example of the flow of processing when executing the content stream CS1 will be described using FIG. 4. For example, the control circuit 10 (CPU) of the control unit 1 analyzes the description and performs processing based on the description. The start in FIG. 4 is the point in time when execution of the content stream CS1 begins.

First, the control unit 1 (control circuit 10) takes out one token from the content stream CS1 (step #21). Tokens are keywords separated by whitespace characters. Then, based on the retrieved token, the control unit 1 determines whether the content stream CS1 is at the end (step #22). When the retrieved token is "endstream", the control unit 1 determines that it is the end stream. When the retrieved token is other than "endstream", the control unit 1 determines that it is not the end.

When it is determined that it is the end (Yes in step #22), the control unit 1 ends the process (END). When determining that the token is not the end (No in step #22), the control unit 1 determines whether the token is an operator (step #23).

Note that when executing the content stream CS1, the control unit 1 sets the operator table from the storage to the memory 22. The operator table is data containing the name of each operator. The control unit 1 executes an operator via an operator table. When the retrieved token matches the name of any operator defined in the operator table, the control unit 1 may determine that the token is an operator. When the retrieved token does not match any operator name included in the operator table, the control unit 1 may determine that the token is not an operator.

If the object does not correspond to any operator (in the case of an object other than an operator) (No in step #23), the control unit 1 stacks the value of the object (token) (step #24). Note that the control unit 1 sets a stack area in the memory 22 for stacking objects (values). That is, the control unit 1 stores an object (value) in the stack area as a value necessary for processing of an operator that will appear later. After stacking, the control unit 1 performs step #21 (returns to step #21).

On the other hand, when it is determined that the operator is the operator (Yes in step #23), the control unit 1 calls the operator (function corresponding to the operator) (step #25). Then, the control unit 1 pops the number of objects used by the called operator (function) (step #26). For example, if the operator is "rg", three values (numeric objects), R, G, and B, are required to execute this operator. In this manner, the control unit 1 reads objects (values) necessary for executing the operator from the stack area.

If three objects (values) are required for execution, but only two objects (values that could be popped) are stacked, the operator (function) cannot be executed. Therefore, the control unit 1 determines whether the number of read objects is sufficient (step #27). If it is insufficient (No in step #27), the control unit 1 determines that there is an error (step #28). In other words, the control unit 1 determines that there is an error in the description of the content stream CS1. In this case, the control unit 1 ends the processing (drawing) based on the content stream CS1 (end).

If there is enough (Yes in step #27), the control unit 1 determines whether the type of the read object (popped value) is appropriate (step #29). If the operator is "rg" or "re", a positive numerical object is required. If at least one object that cannot be used by the operator attempting to execute is read, the control unit 1 determines that the type is not appropriate.

If the type is not appropriate (No in step #29), the control unit 1 determines that there is an error (step #28). In this case, the processing (drawing) based on the content stream CS1 is ended (end). When the type is appropriate (Yes in step #29), the control unit 1 executes the operator based on the object (value) (step #210). After execution, the control unit 1 performs step #21 (returns to step #21).

Image data is drawn by executing content stream CS1. For example, image data of characters of a specified color are arranged in a size specified in the description of the content stream CS1, in a specified font, and at a specified position. Further, a figure is drawn in the specified color at the size specified in the description of the content stream CS1 and at the specified position. It is also possible to paste image data such as photographs.

(Processing of specific object 7)
Next, an example of processing of the specific object 7 in the image processing apparatus 100 according to the embodiment will be described.

The PDF file 6 can include an XObject. XObject is an object that is independent from each page. XObject is an object that is assumed to be executed multiple times while drawing each page of one PDF file. An XObject can be said to be an object that can be referenced on any page.

Form XObject is a type of XObject. The PDF file 6 can include an object (indirect object) called Form XObject. For rendering, the Form XObject contains a content stream CS1. That is, Form XObject includes a description for performing drawing.

The same image or text may be placed on multiple pages. For example, a company's logo may be placed on each page. The same string may be placed in the header or footer on all pages. When drawing the same image, the description of the content stream CS1 will be the same. It is possible for each page to contain the same content stream CS1. However, it is not efficient to include many identical descriptions in the PDF file 6. When drawing each page of one PDF file 6, an object (content stream CS1) that is used multiple times can be included in the PDF file 6 as a Form XObject.

Form XObject is an object (indirect object) to which an object ID (ID number) is attached. Form XObject is an object that is expected to be executed multiple times when drawing one PDF file 6. Form XObject can be executed multiple times during drawing of one page. Also, Form XObject can be executed on any page.

TilingPatternObject is an object that is executed multiple times like Form XObject. TilingPatternObject is an object for drawing a tile pattern. For example, a tile pattern is an image in which rectangles of different colors are arranged according to a certain rule. A tile pattern may be drawn as a background pattern. For example, when each page of one PDF file 6 includes a tile pattern background, TilingPatternObject is executed multiple times.

The image processing apparatus 100 treats these Form XObject and TilingPatternObject as specific objects 7 (see FIG. 7). The specific object 7 is an object that performs different processing from objects other than the specific object 7.

The specific object 7 inherently includes a content stream CS1. In the following description, the content stream CS1 included in the specific object 7 will be referred to as a specific content stream CS2.

When drawing (rasterizing) the image data of each page of one PDF file 6, the specific content stream CS2 may be executed multiple times. The control unit 1 (control circuit 10) converts the specific content stream CS2 and generates converted data 8. The converted data 8 can be said to be a content stream CS1 that has been processed so that it can be processed at high speed.

The control unit 1 caches (stores) the converted data 8 in the memory 22 (see FIG. 1). Instead of the specific content stream CS2, the control unit 1 executes the cached conversion data 8. The rendering result (image data) of the content stream CS1 can be obtained faster than when the specific content stream CS2 is executed as is.

The rendering result (image data obtained by executing the specific content stream CS2) itself is not cached. The size of image data obtained by rasterization may become large. When caching the image data itself, it is necessary to install a memory 22 with a large capacity so that the memory 22 does not run out. The larger the capacity, the more expensive the memory 22 (RAM) is. The converted data 8 is cached instead of the image data. The size of data to be cached is smaller than when caching the drawing result (image data) itself. There is no need to install a large capacity memory 22. The manufacturing cost of the image processing device 100 can be suppressed. Even a low-priced image processing apparatus 100 with a small memory 22 capacity can draw (rasterize) the PDF file 6 at high speed.

(Processing during execution of specific object 7)
Next, an example of processing when the specific object 7 is executed in the image processing apparatus 100 according to the embodiment will be described using FIG. FIG. 5 is a diagram illustrating an example of processing when the specific object 7 is executed in the image processing apparatus 100 according to the embodiment.

Regarding the specific content stream CS2 of the specific object 7, the control unit 1 generates conversion data 8. For example, the control unit 1 generates conversion data 8 for the content stream CS1 of Form XObject. When the PDF file 6 includes a plurality of specific objects 7, the control unit 1 generates conversion data 8 for each specific object 7 (for each specific content stream CS2).

The start of FIG. 5 is when the specific object 7 is called. First, the control unit 1 determines whether the conversion data 8 of the specific content stream CS2 of the called specific object 7 is already cached in the memory 22 (step #31). In other words, after starting drawing (rasterization) based on the PDF file 6, the control unit 1 determines whether the called specific object 7 is called for the first time.

Note that the object ID of the corresponding specific object 7 is attached to the cached conversion data 8 (step #37 to be described later). That is, the control unit 1 also stores the object ID of the specific object 7 corresponding to the converted data 8 in the cache area F2. Note that the object ID is an identification number assigned to an object (indirect object).

When there is an object ID that matches the object ID of the called specific object 7 among the object IDs stored in the cache area F2, the control unit 1 determines that the converted data 8 is already cached in the memory 22. When there is no object ID that matches the object ID of the called specific object 7 among the object IDs stored in the cache area F2, the control unit 1 determines that the converted data 8 is not cached in the memory 22.

When the data has been cached (Yes in step #31), the control unit 1 (control circuit 10) obtains the cached conversion data 8 (step #32). Then, the control unit 1 executes the conversion data 8 (step #33). Thereby, the control unit 1 generates the same drawing result (image data) as the specific content stream CS2. Then, the control unit 1 ends the process of the called specific object 7 (END). For example, the control unit 1 subsequently processes the next object.

If the data has not been cached (No in step #31), the control unit 1 reserves (sets) a generation area F1 for the converted data 8 in the memory 22 (step #34). Then, the control unit 1 sets the conversion data generation operator table in the memory 22 (step #35). For example, the control unit 1 reads an operator table for generating conversion data stored in a storage unit 2 (storage) in a non-volatile manner. Alternatively, the control unit 1 may generate an operator table for generating conversion data.

When executing the normal content stream CS1, the control unit 1 performs processing based on a function corresponding to the executing operator. For example, in the case of the operator "f", the control unit 1 executes a function that performs filling drawing. In the conversion data generation operator table, the name of the operator and the start address of the function corresponding to the operator are defined. By referring to the conversion data generation operator table, the control unit 1 can recognize the start address of the function corresponding to the operator.

The control unit 1 (control circuit 10) generates conversion data 8 using the conversion data generation operator table (step #36). Details of generation of the conversion data 8 will be described later.

The control unit 1 stores the generated conversion data 8 together with the object ID in the cache area F2 of the memory 22 (step #37, see FIG. 1). Then, the control unit 1 sets an operator table for content stream execution instead of the operator table for generating converted data (step #38). In other words, the control unit 1 returns the operator table to a table for normal content stream execution. Then, the control unit 1 executes the generated conversion data 8 (step #33→end). Thereby, the control unit 1 generates the same drawing result (image data) as the specific content stream CS2.

(Generation of conversion data 8)
Next, an example of the process of generating the conversion data 8 according to the embodiment will be described using FIGS. 6 and 7. FIG. 6 is a diagram illustrating an example of a process for generating conversion data 8 according to the embodiment. FIG. 7 is a diagram showing an example of the specific content stream CS2 and its conversion data 8.

Conversion data 8 is data obtained by changing (processing) the description content of specific content stream CS2. Changes are made so that it can be processed faster than the specific content stream CS2. The details of generation of converted data 8 (step #36 in FIG. 5) will be described using FIG. 6.

In the process of generating the converted data 8, some of the processes are the same as when executing the normal content stream CS1. For example, the control unit 1 performs the same error check as when executing the content stream CS1. The start in FIG. 6 is the point in time when generating the conversion data 8 is started.

First, the control unit 1 (control circuit 10) takes out one token from the specific content stream CS2 (step #41). Then, based on the retrieved token, the control unit 1 determines whether the specific content stream CS2 is at the end (step #42). When the retrieved token is "endstream", the control unit 1 determines that it is the end stream. When the retrieved token is other than "endstream", the control unit 1 determines that it is not the end.

When it is determined that it is the end (Yes in step #42), the control unit 1 ends the generation process of the converted data 8 (END). When determining that the token is not the end (No in step #42), the control unit 1 determines whether the token is an operator (step #43).

In order to generate the converted data 8, the control unit 1 sets an operator table for generating converted data in the memory 22 (step #35 in FIG. 5). When the retrieved token matches the name of any operator defined in the conversion data generation operator table, the control unit 1 may determine that the token is an operator. When there is no operator name matching the retrieved token in the conversion data generation operator table, the control unit 1 may determine that the token is not an operator.

If the object does not correspond to any operator (in the case of an object other than an operator) (No in step #43), the control unit 1 stacks the value of the object (token) (step #44). The control unit 1 sets a stack area in the memory 22 for stacking objects (values). After stacking, the control unit 1 performs step #41 (returns to step #41).

On the other hand, when it is determined that the operator is an operator (Yes in step #43), the control unit 1 stores the start address of the function used when executing the operator in the generation area F1 of the conversion data 8 (step #45). Note that the control unit 1 secures the generation area F1 in step #34 described above. The control unit 1 refers to the conversion data generation operator table and recognizes the start address of the corresponding function. The control unit 1 writes the recognized start address into the generation area F1.

Then, the control unit 1 pops the number of objects used by the function whose start address is saved, and writes them into the generation area F1 (step #46). Specifically, the control unit 1 generates conversion data 8 in which an object (value) used in a function corresponding to the start address is placed after the start address (see FIG. 7). For example, if the operator is "rg", three values (numeric objects), R, G, and B, are required to execute this operator. In this case, the control unit 1 writes a maximum of three objects into the generation area F1.

If three objects (values) are required for execution, but only two objects (values that could be popped) are stacked, the operator (function) cannot be executed. Therefore, the control unit 1 determines whether the number of objects written in the generation area F1 is sufficient (step #47). If it is insufficient (No in step #47), the control unit 1 determines that there is an error (step #48). In other words, the control unit 1 determines that there is an error in the description of the specific content stream CS2. In this case, the control unit 1 ends the generation process of the converted data 8 (END).

When there is an error in the description, the control unit 1 may display the description error in the PDF file 6 on the display panel 41. Further, the control unit 1 may cause the communication circuit unit 12 to send a message to the computer 200 that has sent the PDF file 6, informing it of a description error in the PDF file 6.

If there is enough (Yes in step #46), the control unit 1 determines whether the type of the object (popped value) written in the generation area F1 is appropriate (step #49). If the operator is "rg" or "re", a numeric object is required. If at least one object that cannot be used by the operator attempting to execute is read, the control unit 1 determines that the type is not appropriate.

If the type is not appropriate (No in step #49), the control unit 1 determines that there is an error (step #48). The control unit 1 ends the generation process of the converted data 8 (END). When the type is appropriate (Yes in step #49), the control unit 1 performs step #21 (returns to step #21).

FIG. 7 shows a specific example of generation of conversion data 8. FIG. 7 shows an example of a specific content stream CS2 similar to the content stream CS1 of FIG. 3 and its converted data 8. In the process of generating the converted data 8, error checking of the description is performed. Therefore, when executing the conversion data 8, there is no need to check for errors.

In the content stream CS1 before conversion, objects (values) are written in the order of operators. In the conversion data 8, the start address of the function used in the operator is described in the order of the object (value). No need to stack and pop.

Furthermore, in conversion data 8, the operator name is replaced with the start address of the corresponding function. There is no need to refer to the operator table and recognize the starting address based on the operator's name. Necessary functions can be read immediately.

The same rendering result is obtained whether the conversion data 8 is executed or the specific content stream CS2 is executed. However, since measures have been taken to increase the speed, drawing (rasterization) can be performed faster when executing the converted data 8 than when executing the specific content stream CS2. It is possible to shorten the processing time to obtain a drawing result corresponding to the specific content stream CS2.

(Advantages of drawing using conversion data 8)
Next, an example of the advantage of drawing using the conversion data 8 according to the embodiment will be explained using FIG. 8. FIG. 8 is a diagram illustrating an example of the advantage of drawing using the conversion data 8 according to the embodiment.

The drawing result (image data) of the specific content stream CS2 may be enlarged or rotated. In the conventional technology, it is assumed that the drawing result (image data) itself is cached. FIG. 8A shows an example of cached drawing results.

When reusing cached image data to perform enlargement processing or rotation processing, the image quality may deteriorate. FIG. 8C shows an example in which jaggies become noticeable by enlarging the cached drawing result.

The image processing device 100 caches the converted data 8. By specifying the scaling ratio and executing the conversion data 8, smooth drawing results (image data) can be obtained. FIG. 8B shows an example of a drawing result obtained by executing the conversion data 8 according to the specified magnification. For example, the control unit 1 adjusts the object (value) used for drawing according to the specified magnification.

In this way, the image processing apparatus 100 (multifunction peripheral) according to the embodiment includes the memory 22 and the control section 1. Memory 22 caches data. The control unit 1 draws image data of each page of the document file based on objects described in the document file. When executing for the first time a specific content stream CS2, which is a content stream CS1 of a predetermined specific object 7 among objects included in a document file, the control unit 1 corresponds to the operator a description of an operator included in the specific content stream CS2. Conversion data 8 is generated that is replaced with the start address of the function. The control unit 1 caches the generated conversion data 8 in the memory 22. In the second and subsequent executions of the specific content stream CS2, the control unit 1 executes and draws the conversion data cached in the memory 22 instead of the specific content stream CS2.

Conversion data 8 can be generated. Transformed data 8 may be cached in memory 22. In conversion data 8, the operator description is replaced with a numerical value indicating an address. By using the conversion data 8, it is possible to draw faster than when executing the specific content stream CS2.

Do not cache image data obtained by drawing (rasterization) as is. The memory 22 capacity required for cache can be suppressed. It is not necessary to install a large capacity memory 22 in the image processing device 100. The manufacturing cost of the image processing device 100 can be suppressed.

Further, the image drawn by the specific content stream CS2 may be subjected to processing such as enlargement or rotation. When caching object drawing results (image data), image quality may deteriorate if processing such as enlargement or rotation is performed. For example, jaggies (step-like jagged edges) may become noticeable. When using the conversion data 8, a smooth drawing result (image data) can be obtained by specifying the scaling ratio.

The control unit 1 generates conversion data 8 in which an object used in a function corresponding to the start address is placed after the start address. Objects (values) used in functions can be placed after the function. Eliminates the need to stack values used in functions. Function processing can be sped up. The converted data 8 can be executed at high speed.

When executing the specific content stream CS2 for the first time, the control unit 1 generates the conversion data 8 without performing drawing based on the description of the specific content stream CS2. The control unit 1 executes the generated conversion data 8 instead of the specific content stream CS2. After generating the conversion data 8, by executing the conversion data 8, image data corresponding to the specific content stream CS2 can be obtained.

When generating the conversion data 8, the control unit 1 checks whether there is an error in the description of the specific content stream CS2. The control unit 1 generates conversion data 8 when there is no error. It is possible to obtain converted data 8 that does not cause any errors even when executed. In other words, the conversion data 8 has been checked for errors. When executing the converted data 8, there is no need to perform error checking processing that is performed when executing the content stream CS1. The time from the start of execution of the conversion data 8 until the drawing result (image data) is obtained is certainly shorter than the time from the start of execution of the specific content stream CS2 until the drawing result (image data) is obtained. By using the conversion data 8, drawing results can be obtained at high speed.

The document file is PDF file 6. The control unit 1 sets Form XObject and TilingPatternObject as specific objects 7. Conversion data 8 can be generated for the content stream CS1 of objects that are used repeatedly.

The image processing device 100 includes a printer unit 5 that prints based on generated image data. It is possible to provide an image processing apparatus 100 that takes a short time from the start of processing of a document file (PDF file 6) to the start of outputting it without installing a large-capacity memory 22.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the gist of the invention.

INDUSTRIAL APPLICATION This invention can be utilized for the image processing apparatus which handles a PDF file.

100 Image processing device 1 Control unit 22 Memory 5 Printer unit 7 Specific object 8 Conversion data CS2 Specific content stream

Claims (6)

memory for caching data,
drawing image data for each page of the document file based on objects described in the document file;
When a specific content stream, which is a content stream of a predetermined specific object among the objects included in the document file, is executed for the first time, the description of the operator included in the specific content stream is set to the start address of the function corresponding to the operator. Generate the replaced conversion data,
caching the generated conversion data in the memory;
An image processing apparatus characterized in that the image processing apparatus includes a control unit that executes and draws the converted data cached in the memory instead of the specific content stream in the second and subsequent executions of the specific content stream. . The image processing apparatus according to claim 1, wherein the control unit generates the conversion data in which an object used in the function corresponding to the start address is placed after the start address. When the specific content stream is executed for the first time,
The control unit includes:
generating the conversion data without performing rendering based on the description of the specific content stream;
The image processing apparatus according to claim 1 or 2, wherein the generated conversion data is executed instead of the specific content stream. The control unit includes:
When generating the conversion data, check whether there is an error in the description of the specific content stream;
4. The image processing apparatus according to claim 1, wherein the conversion data is generated when there is no error. The document file is a PDF file,
The image processing apparatus according to any one of claims 1 to 4, wherein the control unit uses a Form XObject and a TilingPatternObject as the specific objects. The image processing apparatus according to any one of claims 1 to 5, further comprising a printer section that prints based on the generated image data.

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