JP2004135242A - Image processing apparatus, image reading apparatus, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convert target code data into a suitable encoding scheme corresponding to features of images to be utilized in external equipment or the like in the case of conversion to code data of a format available in the external equipment or the like when using an original encoding scheme or the like in image equipment or the like. <P>SOLUTION: The code data compression-encoding image data are expanded to judge whether the image is a character image or a picture pattern image (step S2). In the case of the character image (Y in step S2), it is converted to a binary image as needed and converted to an MMR code of a little data amount (step S3). In the case of the picture pattern image or the like (N in step S2), it is converted to a multilevel image as needed and converted to a JPEG code of a high picture quality (step S4). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing device, an image reading device, and an image forming device.
[0002]
[Prior art]
Patent Literature 1 discloses an image processing apparatus that optimizes image processing of a read signal, image storage in a memory, parallel operation of a plurality of functions, and each image processing in a so-called multifunction peripheral.
[0003]
[Patent Document 1] JP-A-8-274986 [Problems to be Solved by the Invention]
2. Description of the Related Art In a digital device handling an image, a resolution is increased, a number of gradations is increased, and the like for higher image quality. Then, since the information amount of the image data increases, the image quality improves, but the information amount of the image increases. Therefore, as one of the methods for solving the large data amount, a method of efficiently encoding a multi-tone image can be considered.
[0004]
For encoding such image data, a method suitable for a system using the image data is desired. For example, in a digital copying machine or a so-called multifunction peripheral, generally, a function of enabling rotation as code data, editing as code data, and an encoding method capable of high-speed compression and decompression are generally required.
[0005]
The encoding method is preferably a standard method from the viewpoint of data interchangeability, but there is no standard method that is optimal for such characteristics. The fact is that the JPEG system and the JPEG2000 system are not optimal. For this reason, devices such as digital copiers often employ a unique encoding method suited to the characteristics of the device.
[0006]
However, when these unique encoding methods are used, the code data is not versatile, and therefore, outside of these devices (for example, a computer connected to these devices), the code data can be easily transmitted. There is a problem that it can not be used.
[0007]
Further, there is a disadvantage that an appropriate encoding method according to the characteristics of the image, such as whether the image is a character image or a picture image, cannot be easily used.
[0008]
An object of the present invention is to use a unique encoding method or the like in an image device or the like, and to convert the target code data into code data in a format that can be used by an external device or the like according to the characteristics of the image. The purpose is to convert to an appropriate encoding method and use it in an external device or the like.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a decompression unit for decompressing encoded data obtained by compressing and encoding image data in a predetermined format, a characteristic determination unit for determining a predetermined characteristic of an image from the decompressed image data, A compression unit that selects one of a plurality of types of formats for the decompressed image data in accordance with the determination and re-compresses the encoded data.
[0010]
Therefore, it is possible to convert the coded data coded in the specific format into an appropriate coding method according to the characteristics of the image, and use it in an external device or the like.
[0011]
Note that the features of the image include various features such as whether the image is a character image, a pattern image, a monochrome image, a color image, and the like.
[0012]
According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the feature determination unit determines whether the image is a character image or an image other than a character image as the feature.
[0013]
Therefore, code data encoded in a specific format can be converted into code data in an appropriate format depending on whether the image is a character image or an image other than a character image, and the converted code data can be used in an external device or the like. .
[0014]
According to a third aspect of the present invention, in the image processing device according to the first or second aspect, a storage device that stores the code data and a remaining storage capacity of the storage device are compared with a predetermined first value. And a first comparing unit, wherein the compressing unit performs the second compression encoding according to the result of the comparison regardless of the determination result of the feature determining unit.
[0015]
Therefore, depending on the remaining storage capacity of the storage device, it is possible to select a format with a small amount of data or a format with good image quality even with a large amount of data and convert it to a code of an appropriate format.
[0016]
According to a fourth aspect of the present invention, in the image processing apparatus according to the third aspect, the compression unit determines whether the storage capacity is larger than the first value or smaller when the storage capacity is smaller than the first value. The latter is more suitable for multi-valued images than the latter, and the latter is converted to a multi-valued image or a binary image as required by a coding method more suitable for the binary image than the former, and then the compression encoding is performed again. Perform
[0017]
Therefore, depending on the remaining storage capacity of the storage device, an encoding method suitable for a binary image having a small data amount or an encoding method suitable for a multi-valued image having a high image quality even with a large data amount is selected. Can be converted to codes of various formats.
[0018]
According to a fifth aspect of the present invention, in the image processing apparatus according to the third aspect, the compression unit determines whether the storage capacity is larger or smaller than the first value as a result of the comparison. According to an encoding method suitable for a color image than for the latter, and for the latter, which is more suitable for a black-and-white image than the former, the image is converted into a color image or a black-and-white image as necessary, and then the above-mentioned compression encoding is performed again.
[0019]
Therefore, depending on the remaining storage capacity of the storage device, an encoding method suitable for a black-and-white image with a small data amount or an encoding method suitable for a color image with a high image quality even with a large data amount is selected and an appropriate format is selected. Can be converted.
[0020]
According to a sixth aspect of the present invention, in the image processing apparatus of the third aspect, the image processing apparatus further includes a second comparing unit that compares the storage capacity with a predetermined second value larger than the first value. Means for, if the storage capacity is larger than the second value as a result of the comparison by the second comparing means, further reducing the data amount of the code data stored in the storage device compared to the code data; The compression encoding is performed again in a format that can be performed, and the storage device stores the encoded data after the compression encoding again.
[0021]
Therefore, when the remaining storage capacity of the storage device is exhausted or becomes small, the stored code data is converted into code data capable of further reducing the data amount and stored again, so that the remaining storage capacity of the storage device is secured. can do.
[0022]
According to a seventh aspect of the present invention, there is provided a photoelectric conversion element for reading an image of a document, a storage device for storing the read image data of the document, and image data input / output to / from the storage device as at least a part of a processing target. An image reading apparatus comprising: the image processing apparatus according to claim 1.
[0023]
Therefore, the same operation and effect as the invention according to any one of claims 1 to 6 can be obtained.
[0024]
According to an eighth aspect of the present invention, there is provided the image reading apparatus according to the seventh aspect, and a printer engine for forming an image on a sheet by using image data of a document read by the photoelectric conversion element. Image forming apparatus.
[0025]
Therefore, in the image reading device, the same operation and effect as the invention according to any one of the first to sixth aspects can be obtained.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment of the Invention]
An embodiment of the present invention will be described.
[0027]
FIG. 1 is a block diagram showing an electrical connection of a copying machine 1 in which an image forming apparatus according to the present invention is implemented. A reading unit 11, which is a scanner for optically reading a document, condenses reflected light of lamp irradiation on the document to a photoelectric conversion element such as a CCD (charge coupled device) by an optical system including a mirror and a lens. The photoelectric conversion element is mounted on an SBU (sensor board unit) 12, and the image signal converted into an electric signal by the light receiving element is converted into a digital image signal, and then output from the SBU 12. The image signal output from the SBU 12 is input to a CDIC (compression / decompression and data interface control unit) 13. The transmission of image data between the functional device and the data bus is entirely controlled by the CDIC 13. The CDIC 13 performs image data transfer between the SBU 12, the parallel bus 14, and an IPP (image processing processor) 15, and communication between a system controller (CPU) 16 that controls the entire system and a process controller 27 for image data. Reference numerals 16a and 16b denote ROM and RAM used by the system controller 16. The image signals from the SBUs 12 are transferred to the IPP 15 via the CDIC 13, where the signal deterioration due to the quantization into the optical system and the digital image signal (referred to as the signal deterioration of the scanner system) is corrected and output to the CDIC 13 again. Is done.
[0028]
In the copying machine 1, there are a job for storing the image read by the reading unit 11 in the memory for reuse, and a job for not storing the image in the memory. Each case will be described below. As an example of storing the data in the memory, when a plurality of copies of the same document are copied, the reading unit 11 reads the document only once, stores the document in the memory, and reads the stored data a plurality of times. As an example in which no memory is used, when only one document is copied, the read image may be printed as it is, so that it is not necessary to access the memory.
[0029]
First, when the memory is not used, the image data transferred from the IPP 15 to the CDIC 13 is returned from the CDIC 13 to the IPP 15 again. In the IPP 15, an image quality process for converting the luminance data by the light receiving element into the area gradation is performed. The image data after the image quality processing is transferred from the IPP 15 to the VDC (video data control) 17. Then, the post-processing relating to the dot arrangement and the pulse control for reproducing the dots are performed on the signal changed to the area gradation, and the image forming unit 18 which is a printer engine for forming an image by an electrophotographic method is formed on transfer paper. Form a reproduced image. As a printing method of the image forming unit 18, various methods such as an ink jet method, a sublimation type thermal transfer method, a silver halide photographic method, a direct thermal recording method, and a fusion type thermal transfer method can be used in addition to the electrophotographic method.
[0030]
The flow of image data in the case where image data is stored in a memory and additional processing such as rotation in the image direction and image synthesis are performed at the time of reading the image data will be described. The image data transferred from the IPP 15 to the CDIC 13 is sent from the CDIC 13 to the IMAC 19 (image memory access control) 19 via the parallel bus 14. The IMAC 19 controls access of image data to a MEM (memory module) 20 as a storage device, expands print data to an external PC (personal computer) 21 based on the control of the system controller 16, and effectively uses the memory of the MEM 20. Compression / expansion of image data for the purpose. The image data sent to the IMAC 19 is stored in the MEM 20 after data compression, and the stored data is read out as needed. The read image data is expanded and returned to the original image data, and returned from the IMAC 19 to the CDIC 13 via the parallel bus.
[0031]
After the transfer from the CDIC 13 to the IPP 15, the image data is subjected to image quality processing and pulse control by the VDC 17, and the image data is used to form an image on transfer paper in the image forming unit 18.
[0032]
The digital copying machine 1 is a so-called multifunction machine, and has a facsimile transmission function. The FAX transmission function performs image processing on the read image data by the IPP 15 and transfers the read image data to the FCU (FAX control unit) 22 via the CDIC 13 and the parallel bus 14. The FCU 22 performs data conversion to a communication network and transmits the data to a PN (public line) 23 as FAX data. For FAX reception, the line data from the PN 23 is converted into image data by the FCU 22 and transferred to the IPP 15 via the parallel bus 14 and the CDIC 13. In this case, the VDC 17 performs dot rearrangement and pulse control without performing any special image quality processing, and the image forming unit 18 forms a reproduced image on transfer paper.
[0033]
In a situation where a plurality of jobs, for example, a copy function, a facsimile transmission / reception function, and a printer output function operate in parallel, the allocation of the right to use the reading unit, the imaging unit, and the parallel bus 14 to the job is performed by the system controller 16 and the process controller 27. To control.
[0034]
A process controller (CPU) 27 controls the flow of image data, and a system controller 16 controls the entire system and manages activation of each resource. Reference numerals 27a and 27b denote ROM and RAM used by the system controller 27.
[0035]
The user selects various functions by selecting and inputting the operation panel 24, and sets processing contents such as a copy function and a FAX function.
[0036]
The system controller 16 and the process controller 27 communicate with each other via the parallel bus 14, the CDIC 13, and the serial bus 25. At this time, in the CDIC 13, data format conversion for a data interface between the parallel bus 14 and the serial bus 25 is performed.
[0037]
An MLC (Media Link Controller) 26 realizes a function of code conversion of image data. Specifically, the conversion from the coding method used in the CDIC 13 and the coding method used in the IMAC 19 to another coding method (for example, a standard JPEG method) is performed.
[0038]
2 to 4 are block diagrams showing the configurations of the CDIC 13, the IMAC 19, and the MLC 26, respectively.
[0039]
As shown in FIG. 2, in the CDIC 13, the image data input / output control unit 31 inputs the image data from the SBU 12 and outputs the image data to the IPP 15. The image data input control unit 32 receives the image data corrected by the scanner image in the IPP 15. The input data can be data-compressed by the data compression unit 33 as needed to increase the transfer efficiency of the parallel bus 14. This data is sent to the parallel bus 14 via the parallel data I / F 34. Image data input from the parallel bus 14 via the parallel data I / F 34 is compressed for bus transfer, and can be expanded by the data expansion unit 35 as needed. The decompressed image data is transferred to the IPP 15 by the image data output control unit 36. As an example of the most suitable encoding method used for compression and decompression in the data compression unit 33 and the data decompression unit 35, there is a method in which the codeword length is fixed. The fixed-length coding method can reproduce only an arbitrary part of the image because the position of the image before coding is known in the code state. It is also suitable for image processing and editing.
[0040]
The CDIC 13 has a function of converting parallel data and serial data. The system controller 16 transfers data to the parallel bus 14, and the process controller 27 transfers data to the serial bus 25. The data conversion unit 37 performs data conversion for communication between the two controllers 16 and 27. The serial data I / F 38 is prepared in two systems including the one for the IPP 15, and also serves as an interface with the IPP 15. The command control unit 39 controls various commands.
[0041]
As shown in FIG. 3, the IMAC 19 manages an interface of image data with the parallel bus 14 in the parallel data I / F 41. The IMAC 19 controls storage / reading of image data to / from the MEM 20 and expansion of code data mainly input from the external PC 21 into image data. Examples of the MEM 20 here are a semiconductor memory, a hard disk, or both. The code data input from the PC 21 is stored in the line buffer 42 in the local area. The code data stored in the line buffer 42 is developed into image data in the video control unit 44 based on a development processing command from the system controller 16 input via the system controller I / F 43. The expanded image data or the image data input from the parallel bus 14 via the parallel data I / F 41 is stored in the MEM 20. In this case, the image data to be stored is selected in the data conversion unit 45, data compression is performed as necessary in the data compression unit 46 in order to increase the memory use efficiency, and the address of the MEM 20 is stored in the memory access control unit 47. While storing the image data in the MEM 20. When reading the image data stored in the MEM 20, the memory access control unit 47 controls the read destination address, and the read data is expanded by the data expansion unit 48 as necessary. As an example of an encoding method used for compression and decompression in the data compression unit 46 and the data decompression unit 48, a highly efficient encoding method suitable for saving the memory area of the MEM 20 can be mentioned. This is an encoding scheme that emphasizes efficiency, unlike the encoding scheme that emphasizes functions required for the CDIC 13 described above. When transferring the expanded image data to the parallel bus 14, the data transfer is performed via the parallel data I / F 41.
[0042]
As shown in FIG. 4, in the MLC 26, a system controller I / F 51 includes a data access control unit 52, a data compression unit 53 as a data compression unit, and a data decompression unit as a data decompression unit based on a processing command from the system controller 16. It controls the unit 54, the data conversion unit 55, and the feature amount extraction unit 56 which is a feature determination unit. The data access control unit 52 inputs and outputs data to be code-converted between the IMAC 19 and the CDIC 13. Specifically, input / output with data stored in the MEM 20 via the IMAC 19 is given as an example. For the input data, the original image data is reproduced by the data decompression unit 54 as necessary. The data conversion unit 55 performs data conversion such as image processing and scaling if necessary on the reproduced image data. The converted data is subjected to an encoding process as necessary in the data compression unit 53 to create a code format to be output. The newly created code data is output by the data access control unit 52. If the target data is not a code, the process of the data decompression unit 54 is not performed. Conversely, if the data to be output is not a code, the processing in the data compression unit 53 is not performed. The code data processed by the MLC 26 can be output to the PC 21 via the IMAC 19.
[0043]
The feature amount extraction unit 56 determines the feature of the image of the image data reproduced (executed) in parallel with the expansion of the image data in the data expansion unit 54 or after the expansion of the image data. Here, the feature of the image is, specifically, whether the image is a character image, another image (a pattern image or the like), or whether the image is a color image, a monochrome image, or the like. The feature amount extraction unit 56 can determine whether the image is a character image or a picture image by detecting the edge of the image. Since such processing is well known, a detailed description is omitted.
[0044]
The data conversion unit 55 performs data conversion such as image processing and scaling if necessary on the reproduced image data. The converted data is subjected to a compression encoding process in the data compression unit 53 to create a code format to be output. At the time of processing performed by the data conversion unit 55 and the data compression unit 53, the determination result of the feature amount extraction unit 56 is used. The newly created code data is output by the data access control unit 52 in this manner. If the data input from the data access control unit 52 to the data decompression unit 54 is not a code, the process of the data decompression unit 54 is not performed (bypass the data decompression unit 54). Conversely, when the data to be output from the data access control unit 52 to the outside of the MLC 26 is not a code, the processing in the data compression unit 53 is not performed (bypasses the data compression unit 53).
[0045]
FIG. 5 is a detailed functional block diagram of an example of the data compression unit 53, the data expansion unit 54, and the data conversion unit 55. As described above, the CDIC 13 and the IMAC 19 have different desirable coding methods, and it is assumed that each of the copying machines 1 uses a dedicated coding format. The encoding format used by the CDIC 13 is called a dedicated format, and the encoding format used by the IMAC 19 is called a second dedicated format.
[0046]
The data compression section 53 has a function of compressing into codes of various formats. In this example, a dedicated compression unit 61 for compressing to a code of a dedicated format, an MMR compression unit 62 for compressing to an MMR code (Modified Modified READ Code), and a JPEG compression unit 63 for compressing to a code of JPEG format are provided.
[0047]
The data decompression unit 54 has a function of decompressing codes of various formats. In this example, a dedicated expansion unit 71 for expanding the code of the dedicated format, an MMR expansion unit 72 for expanding the code of the MMR format, and a JPEG expansion unit 73 for expanding the code of the JPEG format are provided.
[0048]
The data conversion unit 55 converts a multi-valued image data into a binary image, converts the multi-valued image data into a binary image, converts the multi-valued color image data into a black-and-white image, A color-to-black and white conversion unit 86 for converting data into data, a black-and-white conversion unit 87 for converting multi-valued black-and-white image data into color image data, and the like are provided.
[0049]
This makes it possible to decompress code data of various formats by the data decompression unit 54, perform predetermined conversion by the data conversion unit 55, and encode by the data compression unit 53 in a predetermined format.
[0050]
For example, if a code in the JPEG format is to be converted into a special format, the code in the JPEG format is first expanded by the JPEG expansion unit 73. Next, if the dedicated format is a binary image encoding format, the multi-value → binary conversion unit 84 converts the format into binary image data. Then, the dedicated compression section 61 performs compression encoding in a dedicated format.
[0051]
With such a configuration, for example, the code of the image stored in the MEM 20 is decompressed by the data decompression unit 48, and thus is converted by the data conversion unit 55 as it is, and is converted by the JPEG compression unit 63 of the data compression unit 53. If the data is compressed to the JPEG format and output to the PC 21, code data that can be easily handled by the PC 21 can be obtained, so that this image can be viewed on the display of the PC 21.
[0052]
Since the binary image has a smaller amount of information than the multi-valued image, the code amount after encoding is generally smaller than that of the multi-valued image. However, there is a possibility that the image quality is inferior to the multi-valued image. When considering a character image and a picture image, a binary image coding method is suitable for a character image, and a multi-value image coding method is suitable for a picture image in terms of a balance between coding efficiency and image quality. . Therefore, if necessary, the multi-valued image data is converted to binary by a multi-valued-to-binary conversion unit 84, and the binary image data is converted to multi-valued by a binary-to-multi-value conversion unit 85. The data compression unit 53 can perform compression encoding in a predetermined format.
[0053]
Similar to the relationship between the binary image and the multi-valued image, in the case of the multi-valued image, there is a relationship between the monochrome image and the color image. Since a black-and-white image has a smaller amount of information than a color image, the code amount after compression encoding is generally smaller than that of a color image. If the color information is not so important, or if the image is a multi-valued image but has no color information, there is no major problem in terms of image quality even if it is handled as a monochrome image. Therefore, if necessary, the multi-valued color image data is converted to black-and-white image data by a color-to-black-and-white conversion unit 86, and the multi-valued black-and-white image data is converted to color image data by a black-and-white-to-color conversion unit 87. The data compression unit 53 can perform compression encoding in a predetermined format.
[0054]
The contents of the processing performed by the system controller 16 with the above configuration will be described. As shown in FIG. 6, the user operates the operation panel 24 even if the image data in the dedicated format that is standardly used in the CDIC 13 and the IMAC 19 is a unique system that is optimal for the digital copying machine 1. Then, when it is requested to output the image data to the external PC 21 or the like (Y in step S1), the feature amount extracting unit 56 determines whether the image is a character image or a picture image (step S2). ). In the case of a character image (Y in step S2), the image is converted into a standard binary image encoding method, for example, an MMR code by the MLC 26 (step S3). (N in step S2), the data is converted into a standard multi-valued image coding method, for example, a JPEG code (step S4), and output to the PC 21 or the like outside the digital copying machine 1 (step S5).
[0055]
More specifically, when converting the dedicated format into the MMR code, the dedicated decompressing unit 71 decompresses the image data encoded in the dedicated format, and if necessary, the multi-valued to binary conversion unit 84 The data is converted into data, and the MMR compression unit 62 performs compression encoding in the MMR format. When the dedicated format is converted to JPEG code, the image data encoded in the special format is expanded by the special expansion unit 71 and converted into multi-value image data by the binary-to-multi-value conversion unit 85 as necessary. Then, the data is encoded by the JPEG compression unit 63 in the JPEG format.
[0056]
Therefore, an encoding method most suitable for the digital copying machine 1 is used inside the digital copying machine 1, and a coding method having high versatility and high encoding efficiency is used outside the digital copying machine 1. Image data can be output.
[0057]
The code conversion by the MLC 26 is also used for code conversion inside the digital copying machine 1. That is, since the binary image has a smaller amount of information than the multi-valued image, the code amount after encoding is generally smaller than that of the multi-valued image. However, the image quality may usually be poor. Therefore, when considering a character image and a picture image, a binary image coding method is suitable for a character image, and a multi-value image coding method is suitable for a picture image in terms of a balance between coding efficiency and image quality. ing.
[0058]
Specifically, image data read by the reading unit 11 or received via the FCU 22 is processed as follows. That is, as shown in FIG. 7, the system controller 16 determines the remaining amount of the MEM 20 by comparing the remaining storage capacity or the used storage capacity of the MEM 20 with a predetermined threshold (step S11). Implement comparison means. When it is determined that the remaining amount is smaller than the predetermined amount (first value) (Y in step S11), the encoding efficiency is high but the image quality is slightly inferior as needed by the multi-value → binary conversion unit 84. After the conversion to the binary image, the image signal is encoded by an encoding method suitable for the binary image (for example, compression encoding is performed by the MMR compression unit 62 in the MMR format) (step S12). When it is determined that the remaining amount is larger than the predetermined amount (N in step S11), if necessary, the binary-to-multi-value conversion unit 85 converts the coding efficiency into a multi-value image with low encoding efficiency but good image quality. The image signal is encoded by an encoding method suitable for the multi-valued image (compression encoding is performed in the JPEG format by the JPEG compression unit 63) (step S13).
[0059]
Then, the remaining amount of the MEM 20 is compared with a predetermined amount (second value) larger than the first value (step S14) to implement a second comparing unit. The second value indicates that the used storage capacity of the MEM 20 is in a full state. If the second storage value exceeds the second value (Y in step S14), the code data stored in the MEM 20 is deleted. If necessary, the multi-level-to-binary conversion unit 84 converts the image signal into a binary image having high encoding efficiency but slightly inferior image quality, and then encoding the image signal using an encoding method suitable for the binary image. Further, the data is converted again into code data having a smaller data amount (for example, compression encoding is performed in the MMR format by the MMR compression unit 62) (step S15), and stored in the MEM 20 again (step S16).
[0060]
According to such processing, an optimal encoding method can be selected according to the amount of usable storage capacity of the MEM 20. Also, select an encoding method that can be stored with the highest image quality until the storage area is full, and if the storage area is full, convert the code to an encoding method with smaller storage capacity and store it Therefore, a free area can be created in the MEM 20 without deleting codes from the storage area.
[0061]
Similarly to the relationship between a binary image and a multi-valued image, in the case of a multi-valued image, there is a relationship between a black-and-white image and a color image, and this can be used. That is, since a black-and-white image has a smaller amount of information than a color image, the code amount after encoding is generally smaller than that of a color image. If the color information is not so important, or if the image is a multi-valued image but has no color information, there is no major problem in terms of image quality even if it is handled as a monochrome image.
[0062]
Therefore, the processing in FIG. 8 may be performed instead of the processing in FIG. That is, the system controller 16 determines the remaining amount of the MEM 20 by comparing the remaining storage capacity or the used storage capacity of the MEM 20 with a predetermined threshold (step S21), and implements a first comparing unit. If it is determined that the remaining amount is larger than the predetermined amount (first value) (Y in step S21), a color-to-black-and-white conversion unit 86 may perform a black-and-white image having high encoding efficiency but slightly inferior image quality as necessary. After the conversion, the image signal is encoded by an encoding method suitable for a monochrome image (step S22). If it is determined that the remaining amount of the MEM 20 is smaller than the first value (N in step S21), the color conversion unit 87 converts the color image into a color image with low encoding efficiency but good image quality as needed, if necessary. The image signal can be encoded by an encoding method suitable for the image (step S23).
[0063]
Then, the remaining amount of the MEM 20 is compared with a predetermined amount (second value) larger than the first value (step S24) to implement a second comparing unit. This second value also indicates that the used storage capacity of the MEM 20 is in a full state. When the second value exceeds the second value (Y in step S24), the code data stored in the MEM 20 is deleted. Then, the image data is encoded by an encoding method suitable for a black-and-white image (step S25), and is further converted into encoded data having a smaller data amount (step S15), and stored in the MEM 20 again.
[0064]
As an example of an encoding method used, as an encoding method suitable for a binary image, in addition to the MMR method, an MH method, an MR method, etc., which are also used in facsimile, are suitable for a multi-valued image. Examples of the encoding method include a JPEG2000 method in addition to the JPEG method. Note that the JPEG system and the JPEG2000 system are suitable for both monochrome images and color images.
[0065]
[Embodiment 2]
Another embodiment will be described as a second embodiment of the present invention.
[0066]
FIG. 9 is a block diagram showing the electrical connection of the image reading device 91 that implements the image reading device of the present invention. In FIG. 9, the same reference numerals as those in FIG. 1 and the following denote the same components as those in the first embodiment, and a detailed description thereof will be omitted. This image reading device 91 is greatly different from the copying machine 1 in that the image reading unit 91 is not provided. Since the image forming unit 18 is unnecessary, the VDC 17 is not mounted.
[0067]
The image data read by the reading unit 11 is digitized by the SBU 12, transferred to the IPP 15 via the CDIC 13, and then subjected to predetermined image processing. This mainly performs deterioration correction of a read image, but also performs gradation processing suitable for a display device using a screen. There are many processes different from the image quality process for transfer paper such as the copying machine 1. At this time, by configuring the IPP 15 with a programmable arithmetic processing unit, only necessary processing procedures need to be set for image quality processing on transfer paper and gradation processing on the screen. A configuration is also possible in which it is not necessary to always have both procedures.
[0068]
The image data after the gradation processing is transferred to the CDIC 13 and sent to the IMAC 19 via the parallel bus 14. The scanner function is realized by using the MEM 20 as a buffer memory and transferring image data to a driver attached to the PC 21. As with the copying machine 1, the system controller 16 and the process controller 27 manage image data and system resources.
[0069]
【The invention's effect】
According to the first aspect of the present invention, it is possible to convert code data encoded in a specific format into an appropriate encoding method according to the characteristics of an image, and use the converted data in an external device or the like.
[0070]
According to a second aspect of the present invention, in the first aspect of the invention, code data encoded in a specific format is converted into code data in an appropriate format depending on whether the image is a character image or an image other than a character image. And can be used by an external device or the like.
[0071]
According to a third aspect of the present invention, in the first or second aspect, a format with a small data amount or a format with good image quality even with a large data amount is selected depending on the remaining storage capacity of the storage device. Then, it can be converted into a code of an appropriate format.
[0072]
According to a fourth aspect of the present invention, in accordance with the third aspect of the present invention, an encoding method suitable for a binary image having a small data amount or an image quality even when the data amount is large depends on the remaining storage capacity of the storage device. It is possible to select a coding method suitable for a multi-valued image with good quality and convert it to a code of an appropriate format.
[0073]
According to a fifth aspect of the present invention, in the third aspect of the present invention, an encoding method suitable for a black-and-white image having a small data amount or an image quality having a large An encoding method suitable for a good color image can be selected and converted to a code of an appropriate format.
[0074]
According to a sixth aspect of the present invention, in the third aspect of the invention, when the remaining storage capacity of the storage device is exhausted or becomes small, the stored code data is converted into code data that can further reduce the data amount. Since the data is converted and stored again, the remaining storage capacity of the storage device can be secured.
[0075]
The inventions according to claims 7 and 8 can provide the same effects as the invention according to any one of claims 1 to 6.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a digital copying machine according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing the overall configuration of a CDIC.
FIG. 3 is a block diagram showing an overall configuration of the IMAC.
FIG. 4 is a block diagram illustrating an overall configuration of the MLC.
FIG. 5 is a block diagram illustrating a detailed configuration of a data compression unit, a data decompression unit, and a data conversion unit of the MLC.
FIG. 6 is a flowchart of a process executed by the digital copying machine.
FIG. 7 is a flowchart of another process executed by the digital copying machine.
FIG. 8 is a flowchart of another process executed by the digital copying machine.
FIG. 9 is a block diagram illustrating an overall configuration of an image reading apparatus according to a second embodiment of the present invention;
[Explanation of symbols]
1 image forming apparatus 18 printer engine 20 storage device 53 compression means 54 decompression means 91 image reading device

Claims (8)

Decompression means for decompressing code data obtained by compressing and encoding image data in a predetermined format,
Feature determining means for determining a predetermined feature of the image from the expanded image data,
Compression means for selecting any one of a plurality of types of formats for the decompressed image data in accordance with this determination and compressing and encoding the image data again;
An image processing apparatus comprising: The image processing apparatus according to claim 1, wherein the characteristic determination unit determines whether the image is a character image or an image other than a character image as the characteristic. A storage device for storing the code data,
First comparing means for comparing the remaining storage capacity of the storage device with a predetermined first value;
With
Irrespective of the determination result of the feature determination unit, the compression unit performs the compression encoding again according to the result of the comparison,
The image processing device according to claim 1. When the storage capacity is larger or smaller than the first value as a result of the comparison, the compression unit is more suitable for a multi-valued image than the former, and the latter is more suitable for a binary image than the former. By a suitable encoding method, after converting to a multi-valued image or a binary image as needed, the compression encoding is performed again.
The image processing device according to claim 3. When the storage capacity is larger than the first value and smaller than the first value as a result of the comparison, the compression unit is a code that is more suitable for a color image than the latter and a code that is more suitable for a black-and-white image than the first. By the conversion method, after converting as necessary to a color image or a black and white image, respectively, perform the compression encoding again,
The image processing device according to claim 3. Second comparing means for comparing the storage capacity with a predetermined second value larger than the first value,
When the storage capacity is larger than the second value as a result of the comparison by the second comparison means, the compression means further increases the data amount of the code data stored in the storage device compared to the code data. Perform the above compression encoding again in a format that can reduce
The storage device stores the code data after the compression encoding again,
The image processing device according to claim 3. A photoelectric conversion element for reading an image of the original,
A storage device for storing the image data of the read original,
The image processing apparatus according to claim 1, wherein the image data input / output to / from the storage device is at least a part of a processing target.
An image reading apparatus comprising: An image reading device according to claim 7,
A printer engine that forms an image on paper using image data of a document read by the photoelectric conversion element,
An image forming apparatus comprising:

Images