JP4765416B2 - Image processing apparatus and image storage method - Google Patents

Description

  The present invention relates to an image processing apparatus including a storage device that stores image data, and more particularly to a technique for encrypting and storing image data.

Recent image processing devices such as Multi Function Peripherals have been developed with built-in HDD (Hard Disk Drive), which is a non-volatile storage device, for storing large amounts of image data. Has been.
Here, when the HDD is discarded by the user or when it is intentionally removed by a malicious person, there is a possibility that information relating to the image data stored in the HDD leaks to the outside.

Therefore, in order to prevent leakage of information related to image data, a technique for storing image data in an HDD after encryption processing has been proposed.
Japanese Patent Laying-Open No. 2005-086582

However, since a processing load is applied during the image data encryption process, there is a problem that the processing capability of the image processing apparatus temporarily decreases by the amount allocated to the process.
The present invention has been made in view of the above points, and an object thereof is to provide an image processing apparatus capable of suppressing a decrease in processing capability.

Therefore, an image processing apparatus according to the present invention is an image processing apparatus that includes a storage device that stores encrypted image data, and includes compression means for JBIG compressing image data, and compressed image data other than JBIG format. Conversion means for converting to image data in JBIG format, all area encryption means for encrypting all areas of image data, and the first read out when decompressing each plane of JBIG compressed image data First area encryption means for encrypting only the area, time required for the first process for encrypting the image data other than JBIG format by the all area encryption means, and conversion to JBIG format image data Compared with the time required for the second process of encryption by the head area encryption means after conversion, a process with a shorter required time is determined. Comprising a determining means for, the, one of the first processing or the second processing is characterized by executing the process it is determined that the required time is shorter by the determining means.

  In the above configuration, the entire area of the image data is not encrypted, but only the first area that is read first when decompressing is expanded out of each plane of the image data that has been JBIG-compressed to form a plane structure. Accordingly, the time required for the encryption process can be shortened while ensuring the security of the image data. Thereby, it can suppress that the processing capability of an image processing apparatus falls with encryption processing.

Further, the compressed image data other than JBIG format, e Bei converting means for converting the image data of the JBIG format, the first part encryption means to encrypt the image data converted into JBIG format by the converting means It is said . Thereby, it is possible to reduce the time required for the encryption process for image data other than the JBIG format.
Also , an all-region encryption unit that encrypts the entire region of the image data, a time required for the first processing for encrypting the image data other than the JBIG format by the all-region encryption unit, and a JBIG by the conversion unit the head area Bei give a determination means for short processing more time required is compared with the time required for the second process of encrypting the encryption means after converting the format image data of the first process or of the second processing, and executing the processing it is determined that the required time is short by the determining means. As a result, processing with a shorter processing time is executed and the processing load is reduced, so that it is possible to prevent the processing capability of the image processing apparatus from being reduced.

  The image processing apparatus according to the present invention further includes an all-region encryption unit that encrypts the entire region of the image data, and a reception unit that accepts an input of a security level from the user. It is desirable to encrypt the image data when the security level received by the receiving unit is higher than normal. When the security level accepted by the user input is high, the security of the image data can be ensured by encrypting the entire area of the image data.

  Here, all-region encryption means for encrypting the entire area of the image data is provided, and the head area encryption means should store the image data in the storage device at the first security level by the received processing job. If it is a job, the image data is encrypted, and the all-region encryption means should store the image data in the storage device at a second security level higher than the first security level. In the case of a high security job, it is desirable to encrypt image data. In the case of a high security job, the security of the image data can be increased by encrypting the entire area of the image data. In addition, when the security level is lower than that of a high security job, only the head area of each plane of image data is encrypted to reduce the time required for the encryption process while ensuring the security of the image data. Therefore, it can suppress that the processing capacity of an image processing device falls.

  The high security job is preferably a confidential print job. Since the confidential print job is normally used when printing a highly confidential document, it is appropriate to perform high security encryption processing when the document file is stored in the storage device. Thus, for confidential print jobs, the security of highly confidential documents can be ensured by encrypting the entire image data area.

Here, it is preferable that the image processing apparatus further includes decryption means for decrypting image data that is JBIG format image data and in which only the head area that is read first when decompressed is encrypted. As a result, it is possible to decrypt the image data that is JBIG compressed and only the head area of each plane is encrypted.
An image storage method according to the present invention is an image storage method executed by an image processing apparatus including a storage device for storing image data, and encrypts the entire area of image data for image data other than JBIG format. The time required for the process 1 and the second process of encrypting only the first area that is read first when decompressing, out of each plane of JBIG-compressed image data after conversion to JBIG format image data A determination step of comparing a time required for the determination and determining a process having a shorter required time, and executing a process determined to have a shorter required time in the determination step of the first process or the second process And a storage step of storing the encrypted image data in the storage device .

In the above method, for image data other than the J BIG format, the time required for the first processing for encrypting the entire area of the image data, and the JBIG-compressed image data after being converted into the JBIG format image data of plane, only the top area is read first when it is stretched by comparing the time required for the second process of encrypting a determination step of determining short processing more time required, the first Of the process or the second process, an encryption step for executing the process determined to have a short required time in the determination step and a storage step for storing the encrypted image data in the storage device are executed. . Thereby , the time required for the encryption process can be shortened while ensuring the security of the image data.

A receiving step for receiving an input of a security level from a user is executed before the determining step ; and if the security level received in the receiving step is a first level, the determining step is executed; When the security level received in the step is a second level higher than the first level, it is desirable to execute the step of encrypting the entire area of the image data without executing the determination step . When the security level accepted by the user input is high, the security of the image data can be ensured by encrypting the entire area of the image data.

If the security level required for the image data is the first level, the determination step is executed, and a second security level required for the image data is higher than the first level. In the case of the level, it is desirable to execute the step of encrypting the entire area of the image data without executing the determination step . Thus, when the security level is the second level, by encrypting the entire area of the image data, it is possible to enhance the security of the image data.

Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of an image processing apparatus. A multi function peripheral (hereinafter referred to as “MFP”) 1 as an image processing apparatus includes a scanner unit 11, a print output unit 13, an operation unit 15, a hard disk drive (HDD) 17, And a control unit 20.

The scanner unit 11 is a known device that reads an image of a set document.
The print output unit 13 is a known device that prints image data using an inkjet method, a laser method, or the like.
The operation unit 15 includes a display panel made of, for example, a liquid crystal touch panel, a numeric keypad, and the like. When a virtual button, a numeric keypad, or the like on the display panel is pressed, the information is transmitted to the CPU 21 of the control unit 20. In the present embodiment, the operation unit 15 includes a security level input button 16 that receives a security level input from the user. The security level is switched between a high level and a normal level when the user presses the security level input button 16.

The HDD 17 is a non-volatile storage device for storing image data.
The control unit 20 includes a CPU 21, a ROM 22, a RAM 23, a compression / decompression unit 24, an encryption / decryption unit 25, and an interface 26 as main components.
The ROM 22 stores a program related to an original reading operation in the scanner unit 11 and a program related to an operation for storing the read image data in the HDD 17.

The CPU 21 reads a necessary program from the ROM 22 and controls various operations in a unified manner while measuring the timing so as to execute a smooth operation.
The RAM 23 is a volatile memory and serves as a work area when the CPU 51 executes a program.
The compression / decompression unit 24 has a function of compressing / decompressing image data. In this example, the image data is compressed by JBIG (Joint Bi-level Image experts Group) method and JPEG (Joint Photographic Experts Group) method.・ Can be extended.

The encryption / decryption unit 25 has a function of encrypting / decrypting image data, and performs encryption processing according to RC4 (Ron's Code 4), for example. A key used for encryption / decryption is stored in the ROM 22 in advance.
The interface 26 is an interface for connecting to a network such as a LAN or a telephone line.

Next, the operation of the MFP 1 will be described. The operation of the MFP 1 includes a copy job, a scan job, a print job, and the like.
In a copy job, an image read by the scanner unit 11 is printed out by the print output unit 13. In the scan job, an image read by the scanner unit 11 is output to another terminal through a network, for example. In the print job, image data is received from a terminal connected via a network, and the image data is printed out by the print output unit 13.

The image data input to the MFP 1 in each processing job is uncompressed data. All input image data is compressed and then encrypted and stored in the HDD 17.
Next, JBIG (Joint Bi-level Image experts Group) will be explained. JBIG is an ITU-T recommendation T.30. 82, ISO / IEC standard 11544, and JIS standard X4311.

FIG. 2 is a configuration diagram showing data of one color component of JBIG compressed image data. As shown in FIG. 2, the image data compressed by JBIG has a plane configuration. When the image data is color, if the image is represented by three colors of red (R), green (G), and blue (B), each color is composed of three planes, and thus the data is 9 planes in total.
Here, in JBIG, the image data is compressed with a bit string, and therefore, when decompressing the image data, the image data needs to be decompressed in order from the first data in each plane.

For this reason, when the head area (the area represented by the hatched portion in FIG. 2) that is first read out in each plane of the image data is encrypted, the image data is stored unless the cipher in the head area is decrypted. It is not stretched accurately.
The present inventors have focused on this point and have come up with the idea of suppressing a decrease in the processing capability of the MFP 1.

  That is, when encrypting JBIG-compressed image data and storing it in the HDD, conventionally, since all areas of the image data were encrypted, it took time to perform the encryption process. In the present embodiment, The time required for the encryption process can be shortened by encrypting only the first area that is read first when decompressing, in each plane of the image data. Thereby, it is possible to prevent the processing capability of the MFP 1 from being temporarily reduced due to the encryption processing.

It should be noted that the encryption of only the head area is specifically data of at least 1 byte, preferably about 2 to 3 bytes, including the head data that is read first when decompressing. It means only encrypting.
The head position of each plane can be detected based on the end marker information “ff02” arranged at the end of each plane. That is, as shown in FIG. 2, the end marker information “ff02” is arranged at the end portion of the plane 1, and the top data of the plane 2 corresponds to the next to the end marker information “ff02”. . Similarly, the head data of the plane 3 can be detected based on the end marker information “ff02” in the plane 2.

Next, with reference to FIG. 3, a process until the MFP 1 stores the image data input together with each job in the HDD will be described. FIG. 3 is a flowchart showing processing until the image data is encrypted and stored in the HDD in the MFP 1.
First, when the MFP 1 receives a job (S101: Yes), the MFP 1 checks the currently set security level (S102). The security level is set by a user input, and is switched to a high mode with a high security level or a normal mode with a normal security level.

When the security level is the normal mode (S102: No), it is determined whether or not the received processing job is a confidential print job (S103).
If the received processing job is not a confidential print job (S103: No), it is determined whether the input image data is in JPEG format (S104).
If the input image data is not in JPEG format (S104: No), the input uncompressed image data is JBIG compressed (S107), and then only the head area of each plane is encrypted (S108). Then, the encrypted image data is stored in the HDD 17 (S110).

  In step S108, the entire area of the image data is not encrypted, but only the head area that is read first when decompressing is encrypted out of each plane of the JBIG-compressed image data. As a result, the time required for the encryption process can be shortened as compared with the case where the entire area of the image data is encrypted, and the processing capacity of the MFP is temporarily prevented from being lowered due to the encryption process. be able to.

  FIG. 4 is a diagram showing a configuration of image management data. In the image management data, information about the compressed data start address, the compressed data size, the compressed data format, and the encryption format is stored separately for each page for one job. Note that the information on the encryption format includes information indicating how many bits from the beginning of the data are encrypted. The image management data is created every time the image data is compressed and encrypted, and stored in the HDD 17 (S110). The image management data is used for managing the compressed / encrypted image data, and is used when the image data is read from the HDD 17 to decrypt the encrypted data and decompress the data.

Returning to step S104, the case where the input image data is in JPEG format (S104: Yes) will be described. Note that the case where the input image data is in the JPEG format corresponds to a case where an image data file in the JPEG format is transferred from another terminal through the network.
If Yes in step S104, the time required for encrypting the entire area of the image data in the JPEG format (hereinafter referred to as “first process”) and the JPEG format image data are converted into the JBIG format image data. Compared with the time required for encrypting only the head area of each plane (hereinafter referred to as “second process”) after the conversion to, the process with the shorter required time is determined (S105). .

The time required for the first processing for the input image data is calculated in advance as the time required to encrypt the entire area for the JPEG format image data having a predetermined capacity. Ask based.
Further, the time required for the second processing for the input image data is the time required for JBIG compression after decompressing the JPEG format image data having a predetermined capacity, and each plane of the JBIG compressed image data. The time required for encrypting only the top area of the first is calculated in advance and obtained based on the calculated data.

  When the required time is shorter in the second process than in the first process (S105: Yes), the second process is executed. That is, the JPEG format image data is expanded (S106) and JBIG compressed (S107) to convert the JPEG format image data into JBIG format image data. Only the head area read out is encrypted (S108). Then, together with the image management data, the encrypted image data is stored in the HDD 17 (S109, S110).

When the required time is shorter in the first process than in the second process (S105: No), the first process is executed. That is, the entire area of the image data is encrypted while the image data remains in the JPEG format (S113). Then, together with the image management data, the encrypted image data is stored in the HDD (S109, S110).
By comparing the time required for the first process and the time required for the second process as described above and executing the process having the shorter required time, the processing load on the CPU 21 is reduced. Therefore, it is possible to suppress a decrease in the processing capability of the MFP 1.

Returning to step S102, when the security level of the image data is set to the high mode in the MFP 1 (S102: Yes), it is determined whether or not the input image data is uncompressed data (S111). ).
If the input image data is compressed data (S111: No), the entire area of the image data is encrypted as it is (S113). If the input image data is uncompressed data (S111: Yes), after JBIG compression (S112), the entire area of the image data is encrypted (S113).

As described above, when the security level is received from the user and the security level is in the high mode, the entire area of the image data is encrypted and stored in the HDD, thereby ensuring the security of the image data.
Returning to step S102, when the security level is the normal mode (S102: No) and the processing job is a confidential print job (S103: Yes), it is determined whether or not the input image data is uncompressed data. Determination is made (S111).

If the input image data is compressed data (S111: No), the entire area of the image data is encrypted as it is (S113). If the input image data is uncompressed (S111: Yes), after JBIG compression (S112), the entire area of the image data is encrypted (S113).
Since the confidential print job is normally used when printing highly confidential image data, it is appropriate to perform high security encryption processing when storing the image data in the HDD. Therefore, as described above, in the case of a confidential print job, it is possible to ensure the security of highly confidential image data by encrypting the entire area of the image data and increasing the security and storing it in the HDD.

The image data in which the entire data area is encrypted in step S113 is stored in the HDD 17 together with the image management data (S109, S110).
As described above, in the present embodiment, with respect to image data for which normal security is sufficient, only the head area of JBIG-compressed image data is encrypted and stored in the HDD 17. While ensuring security, the time required for the encryption process can be shortened, and a temporary decrease in the processing capability of the MFP 1 can be suppressed.

For image data that requires high security, the entire area of the image data is encrypted and stored in the HDD 17, so that the security of the image data is further ensured.
FIG. 5 is a flowchart showing processing when reading out image data stored in the HDD 17.

First, image data is read from the HDD 17 to the RAM 23 (S201). Referring to the image management data corresponding to the image data (S202), whether the read image data is JBIG-compressed and only the head area of each plane is encrypted, or the entire area of the data is encrypted It is determined whether it has been performed (S203).
When only the top area is encrypted (S203: Yes), only the top area is decrypted (S204), and when all the areas are encrypted (S203: No), all the areas are decrypted. The process is executed (S205).

If JBIG expansion is necessary (S206: Yes), JBIG expansion is performed (S207). If further JPEG compression is required (S208: Yes), JPEG compression is performed (S209). Then, the image data is output in a predetermined form (S210).
The case where JBIG decompression is not necessary is a case where image data compressed with JBIG is transmitted as it is by facsimile. The case where JBIG decompression and JPEG compression are required is, for example, a case where image data is transmitted as an image data file to an external terminal via a network such as a LAN.

  Note that the present invention is not limited to an image processing apparatus, and may be an image processing method. Furthermore, the method may be a program executed by a computer. The program is, for example, a magnetic disk such as a magnetic tape or a flexible disk, an optical recording medium such as a DVD-ROM, DVD-RAM, CD-ROM, CD-R, MO, or PD, a flash memory recording medium, or the like. It can be recorded on various readable recording media, and may be produced, transferred, etc. in the form of the recording medium. Various wired and wireless networks including the Internet in the form of programs, broadcasting, electricity In some cases, the data is transmitted and supplied via a communication line, satellite communication, or the like.

  Further, the program need not include all modules for causing the computer to execute the processing described above. For example, a communication program or a program included in an operating system (OS) is installed in an information processing apparatus separately. The various processes of the present invention may be executed by a computer using various general-purpose programs that can be executed. Therefore, it is not always necessary to record all the modules on the recording medium, and it is not always necessary to transmit all the modules. Further, there are cases where predetermined processing can be executed using dedicated hardware.

<Modification>
As described above, the present invention has been described based on the embodiments. However, the content of the present invention is not limited to the specific examples shown in the above-described embodiments. For example, the following modifications are possible. Can think.
(1) In the above description, when the received processing job is a confidential print job, the entire area of the image data is encrypted and stored in the HDD 17, but the received processing job is a job other than the confidential print job. Even so, the entire area of the image data may be encrypted. For example, a configuration in which the user can set a job to store image data in the HDD 17 with high security among a plurality of types of jobs, and the entire area of the image data for the set job may be encrypted. Good.

  (2) In the above, for the sake of simplicity, the case where the image data input to the MFP 1 is uncompressed data and the case where the data is JPEG data is described. May be in PDF format or the like. In this case, the processing may be performed in the same manner as in the case of the image data in the JPEG format described above.

  The present invention can be widely applied to image processing apparatuses that store image data in an HDD. In addition, since the present invention can provide an image processing apparatus that can suppress a temporary decrease in processing capability, its industrial utility value is extremely high.

It is a figure which shows the structure of an image processing apparatus. It is a block diagram which shows the data of one color component of the image data compressed by JBIG. 4 is a flowchart illustrating processing until image data is encrypted and stored in an HDD in the MFP. It is a figure which shows the structure of image management data. 4 is a flowchart showing processing when image data stored in an HDD is read.

Explanation of symbols

1 MFP (image processing device)
DESCRIPTION OF SYMBOLS 11 Scanner part 13 Print output part 15 Operation part 16 Security level input button 20 Control part 24 Compression / decompression part 25 Encryption / decryption part 26 Interface

Claims (8)

An image processing apparatus comprising a storage device for storing encrypted image data,
Compression means for JBIG compressing image data;
Conversion means for converting compressed image data other than JBIG format into image data in JBIG format;
All area encryption means for encrypting all areas of image data;
First area encryption means for encrypting only the first area read out first when decompressing among the planes of JBIG compressed image data ;
For the image data other than JBIG format, the time required for the first process for encrypting by the all-region encryption unit and the first region encryption unit encrypts the image data after the conversion unit converts the image data to JBIG format. A determination means for comparing a time required for the second process and determining a process having a shorter required time;
With
An image processing apparatus that executes a process of the first process or the second process that is determined to be short by the determination unit. Further comprising a reception hand stage to accept the input of the security level from Yu over The,
If before Symbol security level accepting unit accepts a higher than normal, according to claim 1, wherein without performing a determination by the determination means, characterized by encrypting the image data by the total area encryption means The image processing apparatus described. Acceptance is processing jobs, or a job to be stored in the storage device image data in a first security level, to be stored in the storage device at a higher than the first security level second security level A determination unit for determining whether the job is a high security job ;
When the determination unit determines that the received processing job is a high security job, the image data is encrypted by the all-region encryption unit without executing the determination by the determination unit. The image processing apparatus according to claim 1. The image processing apparatus according to claim 3 , wherein the high security job is a confidential print job. 2. The image processing apparatus according to claim 1, further comprising decryption means for decrypting the image data in JBIG format, wherein only the head area that is read first when decompressed is encrypted. The image processing apparatus according to claim 4 . An image storage method executed by an image processing apparatus including a storage device for storing image data,
For image data other than the JBIG format, the time required for the first processing for encrypting the entire area of the image data, and the JBIG-compressed image data after being converted into JBIG-format image data, are decompressed. A determination step of comparing a time required for the second process for encrypting only the first area read out first and determining a process with a shorter required time;
An encryption step for executing a process determined to have a short required time in the determination step of the first process or the second process;
A storage step of storing the encrypted image data in the storage device . A reception step of accepting an input of a security level from a user before the determination step ;
If the security level received in the reception step is the first level, execute the determination step ;
If the security level received in the receiving step is a second level higher than the first level, executing the step of encrypting the entire area of the image data without executing the determining step. The image storage method according to claim 6, wherein: If the security level required for the image data is the first level, execute the determination step ;
When the security level required for the image data is the second level higher than the first level, the step of encrypting the entire area of the image data is executed without executing the determination step. The image storage method according to claim 6 .

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