JP5312273B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  As a data format of image data (print data) that can be interpreted by an image forming apparatus having a printing function such as a printer or a multifunction peripheral, PDL: Page Description Language, for example, PostScript, PCL (Printer Control Language), etc. However, it is mainly used conventionally.

  In recent years, in addition to the above data formats, PDF (Portable Document Format), XPS (XML Paper Specification), HTML (HyperText Markup Language), XML (Extensible Markup Language), XML, etc. are input images. An increasing number of image forming apparatuses can be used as the data format of data (print data) (see, for example, Patent Documents 1 and 2).

  In such a device that can use a large number of image data, in order to specify the PDL of the image data, a vendor-specific control code is embedded in the image data, or the user designates it by operating the console of the device.

  In addition, there is a technique in which the apparatus analyzes the header of received input image data and identifies the PDL of the input image data (see, for example, Patent Document 3).

  FIG. 8 is a flowchart for explaining an example of a method for specifying the data format of input image data as one of the XPS format, the TIFF (Tagged Image File Format) format, and the PS (PostScript) format.

As shown in FIG. 8, first, the head portion of the input image data is read (step S101). If the leading portion is 0x504B0304 (“PK ..” in ASCII) (step S102), the input image data is interpreted as an XPS format (step S103). If the head portion is 0x4D4D002A ("MM .." in ASCII) or 0x49492A00 ("II .." in ASCII) (step S104), the input image data is interpreted as TIFF format (step S104). Step S105). If the head portion is “%! PS” (step S106), the input image data is interpreted as a PostScript format (step S107). If the head part is not one of the above identification codes, the data format cannot be specified, and error processing is performed (step S108). Then, the input image data is interpreted as the specified data format, drawing processing is performed according to the interpretation (step S109), and raster data for printing is generated.

JP 2008-234119 A JP 2008-234506 A JP 20051966751

  However, as described above, when the data format of the input image data is automatically specified only from the head portion of the input image data, the header portion of the input image data is not correctly described, or the header portion is If it is damaged, an error may occur during interpretation, and the input image data may not be interpreted as the original data format.

  Further, when the head portion of text data or binary data that is not supported by the device (that is, data that cannot be input image data) coincides with the head portion of the input image data that is supported by the device, such a case. Data is interpreted as input image data. As a result, a large number of meaningless pages may be printed or unexpected problems may occur.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of accurately specifying the data format of input image data and accurately interpreting the input image data.

  In order to solve the above problems, the present invention is configured as follows.

An image forming apparatus according to the present invention includes a plurality of data analysis units that interpret image data in a plurality of data formats, a drawing processing unit that performs drawing processing according to an interpretation result by the data analysis unit, and an input image input from the outside A data format determination unit that refers to data, determines the data format of the input image data, and causes the data analysis unit corresponding to the data format of the input image data to interpret the input image data. A communication device that temporarily stores the buffer; and a storage device that stores the input image data . When the input image data matches a predetermined head code of one of the plurality of data formats as a result of the determination, the data format determination unit inputs the data to the data analysis unit corresponding to the data format. When a format error occurs during the processing of input image data by the data analysis unit or the drawing processing unit when interpretation of the image data is executed, the input data is interpreted by another data analysis unit among the plurality of data analysis units. Let it run. The data analysis unit that first interprets the input image data among the plurality of data analysis units reads the input image data from the communication buffer, executes the interpretation of the read input image data, and reads the input image Store the data in a storage device. Of the plurality of data analysis units, the data analysis unit that executes the interpretation of the input image data for the second time and thereafter reads the input image data from the storage device and executes the interpretation of the read input image data.

As a result, when the data format of the input image data is automatically specified from the input image data, even if the header portion of the input image data is not described correctly or the header portion is damaged during communication, a plurality of Since the data analysis unit performs data interpretation, it is possible to accurately specify the data format of the input image data and accurately interpret the input image data. Furthermore, even when the head portion of text data or binary data that is not supported by the device (that is, data that cannot be input image data) coincides with the head portion of the input image data that is supported by the device, this is the case. Data is not interpreted as input image data. As a result, it is possible to prevent a large number of meaningless pages from being printed or unexpected troubles from occurring. Furthermore, even when data interpretation is performed a plurality of times, it is possible to prevent the input image data from staying in the communication buffer.

  In addition to the image forming apparatus described above, the image forming apparatus according to the present invention may be configured as follows. In this case, the data analysis unit that first interprets the input image data among the plurality of data analysis units reads the input image data from the communication buffer, and if a format error occurs in the middle of the input image data, the input image data The interpretation of the data is stopped, and the remaining input image data stored in the communication buffer is read out and stored in the storage device.

  In addition to the image forming apparatus described above, the image forming apparatus according to the present invention may be configured as follows. In this case, the plurality of data analysis units include a data analysis unit that interprets XPS format image data.

  In addition to the image forming apparatus described above, the image forming apparatus according to the present invention may be configured as follows. In this case, the data analysis unit that interprets the image data in the XPS format reads the signature in the input image data, specifies the block size based on the value of the signature, and advances the data reading position by that size. The process is repeatedly executed until a signature indicating the central directory record is read. If the signature value does not match any of the default signature values, it is determined that a format error has occurred.

  In addition to the image forming apparatus described above, the image forming apparatus according to the present invention may be configured as follows. In this case, the data format determination unit switches between the data analysis units until the interpretation of the input image data is completed without causing a format error or until all of the data analysis units interpret the input image data. Interpret image data.

  According to the present invention, in the image forming apparatus, it is possible to accurately specify the data format of the input image data and accurately interpret the input image data.

FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the image forming apparatus shown in FIG. FIG. 3 is a flowchart for explaining the operation of the data analysis unit for XPS in the image forming apparatus shown in FIG. FIG. 4 is a diagram showing a data structure in the ZIP format. FIG. 5 is a flowchart for explaining the operation of the data analysis unit for PDF in the image forming apparatus shown in FIG. FIG. 6 is a flowchart for explaining the operation of the TIFF data analysis unit and the TIFF data drawing process by the drawing processing unit in the image forming apparatus shown in FIG. FIG. 7 is a flowchart for explaining the operation of the data analysis unit for JPEG in the image forming apparatus shown in FIG. FIG. 8 is a flowchart for explaining an example of a method for specifying the data format of the input image data.

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

  FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus includes an arithmetic processing device 1, a communication device 2, a memory 3, a storage device 4, and a print engine 5. The arithmetic processing device 1, the communication device 2, the memory 3, the storage device 4, and the print engine 5 can communicate data with each other via a bus or the like.

  The communication device 2 is connected to a host device such as a personal computer, and receives input image data through a peripheral device interface such as a USB (Universal Serial Bus) or a parallel interface. The memory 3 is a RAM (Random Access Memory) or the like and stores various data. A part of the storage area of the memory 3 is used as a communication buffer 3 a for temporarily storing data received by the communication device 2. The storage device 4 is a nonvolatile mass storage device such as a hard disk drive or a flash memory. The print engine 5 is an apparatus that prints an image on printing paper based on drawing data (raster data) generated from input image data by the arithmetic processing apparatus 1.

  The arithmetic processing device 1 has a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, and the like (not shown), and is a device that loads a program into the RAM and executes it by the CPU. Note that the memory 3 may be used as the RAM. The arithmetic processing device 1 functions as a data acquisition unit 11, a data format determination unit 12, a plurality of data analysis units 13-1 to 13-N, and a drawing processing unit 14 by executing a program on the CPU.

  The data acquisition unit 11 is controlled by the data format determination unit 12 or the data analysis units 13-1 to 13-N and reads input image data from the communication buffer 3a or the storage device 4.

  The data format determination unit 12 determines the data format of the input image data with reference to the input image data, and the data analysis unit 13-i (i = 1,..., N) corresponding to the data format of the input image data. ) To interpret the input image data.

  The data format determination unit 12 interprets the input image data to the data analysis unit 13-i corresponding to the data format when the input data image matches a predetermined head code of one of the data formats. Is executed. Furthermore, when a format error occurs during processing of input image data by the data analysis unit 13-i or the drawing processing unit 14, the data format determination unit 12 determines whether another data analysis unit 13-1 to 13-N The data analysis unit 13-j (j = 1,..., N and j ≠ i) is caused to execute interpretation of input image data. When a format error occurs during the processing of the input image data by the data trace unit 13-j, the data format determination unit 12 uses another data analysis unit 13- in the plurality of data analysis units 13-1 to 13-N. The interpretation of the input image data is executed at k (k = 1,..., N and k ≠ i, j).

  As described above, the data format determination unit 12 normally completes the interpretation of the input image data without generating a format error, or determines whether the input image data is stored in all of the data analysis units 13-1 to 13-N. Until the interpretation is executed, the data analysis unit 13-i is successively switched to execute the interpretation of the input image data. A format error is a syntax error in the data format.

  The data analysis units 13-1 to 13-N are processing units that interpret image data in a plurality of data formats, respectively. For example, in this embodiment, data analysis units 13-1 to 13-4 (N = 4) corresponding to the XPS format, PDF format, TIFF format, and JPEG (Joint Photographic Experts Group) format are provided.

  The drawing processing unit 14 is a processing unit that performs drawing processing according to the interpretation result by the data analysis unit 13-i (i = 1,..., N). In the rendering process, raster data for printing is generated.

  Next, the operation of the above apparatus will be described. FIG. 2 is a flowchart for explaining the operation of the image forming apparatus shown in FIG.

  When receiving the input image data, the communication device 2 stores the input image data in the communication buffer 3a. Next, the data format determination unit 12 uses the data acquisition unit 11 to acquire the leading portion of the input image data from the communication buffer 3a (step S1).

  The data format determination unit 12 determines whether or not the top of the acquired data is 0x504B0304 (“PK ..” in ASCII) (step S2). When it is determined that the top of the acquired data is 0x504B0304 (“PK ..” in ASCII), the data format determination unit 12 specifies the data format of the input image data as XPS (step S3).

  On the other hand, when it is determined that the top of the acquired data is not 0x504B0304 (“PK ..” in ASCII), the data format determination unit 12 determines whether the top of the acquired data is “% PDF”. Is determined (step S4). If it is determined that the top of the acquired data is “% PDF”, the data format determination unit 12 specifies the data format of the input image data as PDF (step S5).

  On the other hand, if it is determined that the top of the acquired data is not “% PDF”, the data format determination unit 12 determines that the top of the acquired data is 0x4D4D002A (“MM ..” in ASCII) or 0x49492A00 (ASCII) Then, it is determined whether or not “II ..”) (step S6). When it is determined that the beginning of the acquired data is 0x4D4D002A (“MM ..” in ASCII) or 0x49492A00 (“II ..” in ASCII), the data format determination unit 12 inputs the input image data. Is specified as TIFF (step S7).

  On the other hand, if it is determined that the beginning of the acquired data is not 0x4D4D002A ("MM .." in ASCII) or 0x49492A00 ("II .." in ASCII), the data format determination unit 12 acquires It is determined whether or not the beginning of the data is 0xFFD8 (step S8). If it is determined that the beginning of the acquired data is 0xFFD8, the data format determination unit 12 specifies the data format of the input image data as JPEG (step S9).

  On the other hand, if it is determined that the top of the acquired data is not 0xFFD8, the data format determination unit 12 determines that the top of the acquired data is not one of the above identification codes, so that the data format of the input image data is A default data format is designated (step S10). The default data format is set from data formats that can be used with this apparatus (for example, XPS format). For example, the data format determination unit 12 stores the processing history of the input image data in the storage device 4, analyzes the history and analyzes the data format of the input image data received last time, or the input image data received in the past The most common data format can be set. The system administrator may set a default data format in the image forming apparatus in advance.

  In this way, the data format determination unit 12 specifies the data format of the received input image data, calls the data analysis unit 13-i corresponding to the specified data format, and interprets the received input image data. Is executed (step S11).

  When the data interpretation process by the data analysis unit 13-i is completed, the data format determination unit 12 determines whether or not a format error has occurred during the data interpretation process (step S12). When a format error occurs during the data interpretation process, the data analysis unit 13-i generates a format error occurrence log. The data format determination unit 12 determines whether a format error has occurred during the data interpretation process based on the presence / absence of a format error occurrence log.

  When the data format determination unit 12 determines that a format error has not occurred during the data interpretation process by the data analysis unit 13-i, the data format determination unit 12 causes the drawing processing unit 14 to execute the drawing process based on the data interpretation (step S13). .

  When the drawing processing by the drawing processing unit 14 is completed, the data format determination unit 12 determines whether a format error has occurred during the drawing processing (step S14). For example, when the input image data includes bitmap image data as in the case of TIFF, there is no need to interpret the data body in the data analysis unit 13-i. It is determined whether it has occurred.

  If no format error has occurred during the data interpretation process and the drawing process, the raster image data for printing has been generated normally, and the process ends.

  On the other hand, if it is determined that a format error has occurred either during the data interpretation process or during the rendering process (steps S12 and S14), the data format determination unit 12 first sets all the data analysis units 13-1 ~ 13-N determines whether or not the interpretation of the input image data has already been executed (step S15). If any data analysis unit 13-j has not yet interpreted the input image data as a result of the determination, the data format determination unit 12 interprets the input image data by the data analysis unit 13-j. Is executed (step S16). When the data interpretation process by the data analysis unit 13-j is completed, the data format determination unit 12 performs the same process as that after the data interpretation process by the data analysis unit 13-i (that is, the process after step S12). . Therefore, when a format error occurs again, a data interpretation process is performed by another data analysis unit 13-k that has not yet interpreted the input image data.

  If it is determined in step S15 that all of the data analysis units 13-1 to 13-N have already interpreted the input image data, the data format determination unit 12 receives the received input image. Since there is no data analysis unit that can correctly interpret the data, error processing (such as displaying an error message) is executed (step S17), and the processing is terminated.

  In this way, the input image data is interpreted by the data analysis unit 13-i that conforms to the data format of the input image data.

  Next, operations of the data analysis units 13-1 to 13-N will be described.

(A) XPS data analysis unit 13-1

  FIG. 3 is a flowchart for explaining the operation of the XPS data analysis unit 13-1 in the image forming apparatus shown in FIG.

  First, the data analysis unit 13-1 activates the XPS interpreter (step S21), and interprets each block in the input image data in order.

  Here, the input image data in the XPS format will be described.

  The input image data in the XPS format is data compressed in the ZIP format. FIG. 4 is a diagram showing a data structure in the ZIP format. As shown in FIG. 4, the ZIP format data includes one or more sets of a local file header (Local File Header), file data (File Data) and a data descriptor (Data Descriptor), a central directory (Central Directory), In addition, an End Of Central Directory Record is included. The end of central directory record is located at the end of the ZIP data.

  The central directory has one or more file headers and a digital signature. Local file headers, file headers and digital signatures in the central directory, and end-of-central directory records have signatures at the beginning of them. The signature is 4-byte data and has a value specific to the field type. The signature value of the local file header is 0x04034b50. The value of the signature of the file header in the central directory is 0x02014b50. The signature value of the digital signature in the central directory is 0x05054b50. The value of the signature of the end of central directory record is 0x06054b50.

  These blocks have a fixed length. However, the file data has a variable length, and its size is included in the local file header.

  Therefore, the data analysis unit 13-1 uses the data acquisition unit 11 to read out these blocks one by one. The data analysis unit 13-1 reads the signature in each block of the input image data, and specifies the block size based on the signature value. The data analysis unit 13-1 repeatedly executes the process of advancing the data reading position by the specified size until the signature indicating the end of central directory record is read.

  At this time, the data analysis unit 13-1 determines whether or not the input image data is already stored in the storage device 4 (step S22). If the input image data is not already stored in the storage device 4, the data analysis unit 13-1 reads out data for one block from the communication buffer 3 a using the data acquisition unit 11 and stores it in the storage device 4. (Step S23). If the input image data has already been stored in the storage device 4, the data analysis unit 13-1 reads data for one block from the storage device 4 using the data acquisition unit 11 (step S24). Thereafter, the data analysis unit 13-1 determines whether or not the signature value in the read block matches any of the predetermined signature values (step S25).

  When it is determined that the signature value in the read block matches one of the predetermined signature values, the data analysis unit 13-1 determines that a format error has not occurred in the block, and Block interpretation is executed (step S26).

  When the interpretation block is the end of the input image data, that is, when the signature indicating the end-of-central directory record is not read in step S23 or S24 (step S27), the data analysis unit 13 -1 reads the next block from the communication buffer 3a or the storage device 4 (step S23 or S24), and executes the processing from step S25 on that block.

  When the format error has never occurred and the interpretation is completed up to the last block of the input image data, that is, when the signature indicating the end of central directory record is read in step S23 or S24 (step S27). ), The data interpretation process ends.

  On the other hand, if it is determined in step S25 that the signature value in the read block does not match any of the default signature values, the data analysis unit 13-1 determines that a format error has occurred and inputs It is determined whether the image data is already stored in the storage device 4 (step S28). If the input image data is not already stored in the storage device 4, the data analysis unit 13-1 reads the remaining block data from the communication buffer 3a and stores it in the storage device 4 (step S29). Furthermore, the data analysis unit 13-1 generates a format error occurrence log and stores it in the storage device 4 or the memory 3 (step S30). The format error occurrence log includes the type of data format handled by the data analysis unit 13-i in which the format error has occurred. When a format error occurs, the data interpretation process ends after recording the format error occurrence log.

  In this way, interpretation processing of input image data in the XPS format is performed.

(B) Data analysis unit 13-2 for PDF

  FIG. 5 is a flowchart for explaining the operation of the data analysis unit 13-2 for PDF in the image forming apparatus shown in FIG.

  The data analysis unit 13-2 activates the PDF interpreter (step S31) and interprets the input image data. First, the data analysis unit 13-2 determines whether input image data is stored in the communication buffer 3a (step S32). If the input image data is stored in the communication buffer 3a, the data analysis unit 13-2 uses the data acquisition unit 11 to read out the input image data from the communication buffer 3a and store it in the storage device 4 (step S33). ).

  Then, the data analysis unit 13-2 starts interpreting the input image data (step S34), and monitors the presence or absence of a format error (step S35) until the interpretation of the input image data ends (step S36). When the interpretation is completed up to the end of the input image data without causing any format error, the data interpretation process is finished.

  On the other hand, when a format error occurs, the data analysis unit 13-2 generates a format error occurrence log and stores it in the storage device 4 or the memory 3 (step S37). When a format error occurs, the data interpretation process ends after recording the format error occurrence log.

  In this way, interpretation processing of input image data in PDF format is performed.

(C) Data analysis unit 13-3 for TIFF

  FIG. 6 is a flowchart for explaining the operation of the TIFF data analysis unit 13-3 and the TIFF drawing process by the drawing processing unit 14 in the image forming apparatus shown in FIG.

  As shown in FIG. 6A, the data analysis unit 13-3 activates the TIFF interpreter (step S41) and interprets the input image data. First, the data analysis unit 13-3 determines whether input image data is stored in the communication buffer 3a (step S42). If the input image data is stored in the communication buffer 3a, the data analysis unit 13-3 uses the data acquisition unit 11 to read out the input image data from the communication buffer 3a and store it in the storage device 4 (step S43). ).

  Then, as shown in FIG. 6B, the drawing processing unit 14 starts the drawing process based on the data in the TIFF format (step S51) until the drawing process based on the bitmap data of the input image data is completed. (Step S53), the presence or absence of a format error is monitored (Step S52).

  If a format error occurs during the drawing process, the drawing processing unit 14 determines whether a format error has occurred in the first page (step S54). When a format error occurs in the first page, the drawing processing unit 14 generates a format error occurrence log and stores it in the storage device 4 or the memory 3 (step S55). On the other hand, when a format error occurs on the second page and thereafter, the drawing processing unit 14 continues the drawing process. Since the TIFF format data can include multiple pages of image data, only when a format error occurs on the first page, it is determined that the data format is erroneously recognized, and the input image data is processed by switching the data format. To do.

  Therefore, if no format error occurs on the first page, the drawing process ends when the drawing process is completed to the end of the input image data.

  In this way, interpretation processing and drawing processing of input image data in the TIFF format are performed.

(D) Data analysis unit 13-4 for JPEG

  FIG. 7 is a flowchart for explaining the operation of the data analysis unit 13-4 for JPEG in the image forming apparatus shown in FIG.

  The data analysis unit 13-4 activates the JPEG interpreter (step S61) and interprets the input image data. First, the data analysis unit 13-4 determines whether or not input image data is stored in the communication buffer 3a (step S62). If the input image data is stored in the communication buffer 3a, the data analysis unit 13-4 uses the data acquisition unit 11 to read out the input image data from the communication buffer 3a and store it in the storage device 4 (step S63). ).

  Then, the data analysis unit 13-4 starts interpreting the input image data (step S64), and monitors whether there is a format error (step S65) until the interpretation of the input image data is completed (step S66). When the interpretation is completed up to the end of the input image data without causing any format error, the data interpretation process is finished.

  On the other hand, when a format error occurs, the data analysis unit 13-4 generates a format error occurrence log and stores it in the storage device 4 or the memory 3 (step S67). When a format error occurs, the data interpretation process ends after recording the format error occurrence log.

  In this way, interpretation processing of input image data in JPEG format is performed.

  As described above, according to the above-described embodiment, the data format determination unit 12 determines that the data analysis unit 13 corresponding to the data format corresponds to the default head code of one data format among the plurality of data formats. -I causes input image data to be interpreted. Further, when a format error occurs during the processing of input image data in the data analysis unit 13-i or the drawing processing unit 14, the data format determination unit 12 determines whether another data analysis unit 13-1 to 13-N The data analysis unit 13-j is caused to execute interpretation of input image data.

  As a result, when the data format of the input image data is automatically specified from the input image data, even if the header portion of the input image data is not described correctly or the header portion is damaged during communication The data interpretation is executed by a plurality of data analysis units 13-i, 13-j,. Therefore, the input image data can be accurately interpreted by accurately specifying the data format of the input image data.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

For example, in the above embodiment, input image data of four types of data formats can be used, but input image data of two types, three types, five types or more of data formats may be usable. Further, input image data having a data format other than the above-described four types of data formats may be usable.
In the above embodiment, the data format determination unit 12 specifies the default data format as the data format of the input image data in step S10 of FIG. 2, but the processing may be terminated.

  The present invention is applicable to, for example, an image forming apparatus that can handle input image data in a plurality of data formats.

2 Communication device 3a Communication buffer 4 Storage device 12 Data format determination unit 13-1 to 13-N Data analysis unit 14 Drawing processing unit

Claims (5)

A plurality of data analysis units for interpreting image data in a plurality of data formats,
A drawing processing unit that performs a drawing process according to an interpretation result by the data analysis unit;
Data format determination in which the input image data input from the outside is referred to determine the data format of the input image data, and the data analysis unit corresponding to the data format of the input image data interprets the input image data and parts,
A communication device that receives the input image data and temporarily stores it in a communication buffer;
A storage device for storing the input image data ,
When the input image data matches a predetermined head code of one data format among the plurality of data formats as a result of the determination, the data format determination unit determines whether the data analysis unit corresponding to the data format The input image data is interpreted, and when a format error occurs during the processing of the input image data by the data analysis unit or the drawing processing unit, another data analysis unit among the plurality of data analysis units , Executing interpretation of the input image data ,
The data analysis unit that first interprets the input image data among the plurality of data analysis units reads the input image data from the communication buffer, executes interpretation of the read input image data, and reads Storing the input image data in the storage device;
Of the plurality of data analysis units, a data analysis unit that interprets the input image data from the second time onward reads the input image data from the storage device, and executes interpretation of the read input image data ,
An image forming apparatus. Of the plurality of data analysis units, a data analysis unit that first interprets the input image data reads the input image data from the communication buffer, and performs a format in the middle of executing the interpretation of the input image data. If an error occurs, stops interpretation of the input image data, the image formation according to claim 1, wherein reading the rest of the input image data stored in the communication buffer and to store in the storage device apparatus. 3. The image forming apparatus according to claim 1, wherein the plurality of data analysis units include a data analysis unit that interprets XPS format image data. The data analysis unit that interprets image data in the XPS format reads a signature in the input image data, specifies a block size based on the value of the signature, and advances a data reading position by the size. It is repeatedly executed until a signature indicating the central directory record is read, and it is determined that a format error has occurred when the value of the signature does not match any of the predetermined signature values. 3. The image forming apparatus according to 3 .   The data format determination unit switches the data analysis unit until the interpretation of the input image data is completed without a format error or until all of the plurality of data analysis units interpret the input image data. The image forming apparatus according to claim 1, wherein the input image data is interpreted.

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