The present application claims the priority under the Paris Convention based on Japanese Patent Application No. 2014-178304 filed on Sep. 2, 2014, in accordance with the provisions in Article 119 in the United States Patent Law.
1. Field of the Invention
The present invention relates to an image processing method, an image forming method, an image processing system, and an image forming apparatus. In particular, the present invention relates to a technique to handle image data of a dot sequential format at high speed without increasing the cost of hardware in image processing and image formation.
2. Description of Related Art
As an image forming apparatus, there exist a scanner, a printer, a copier, a facsimile machine, a composite machine (MFP: Multifunction Peripheral) equipped with these functions by a single set, and the like. These image forming apparatuses are required to store various kinds of data for each job. Examples of various kinds of data include scan data acquired by scanning, print data (image data before being processed by RIP (Raster Image Processor)) transmitted from external devices, and image data (image data after having been processed by RIP) rasterized as bit map data. Accordingly, in such an image forming apparatus, a hard disk drive unit (HDD; Hard Disk Drive) tends to be mounted as a nonvolatile storage section for storing a large amount of image data.
Further, in recent years, image data handled by an image forming apparatus have been increasing in terms of each of the number of data and an amount of data. Then, at the time of storing image data in the above-mentioned HDD, generally, the image data are stored after having been made in a compressed state.
In a commercial printing system, not only a conventional offset printing apparatus, but also an image forming apparatus of an electrophotographying type has been used. Herein, as compared with a printing system in a general office, such a commercial printing system is characterized in that a data size of print data is extremely large. Therefore, print data having been input are configured to be stored once in a HDD which is cheap and has a large capacity. Subsequently, the print data are converted into image data by RIP processing, and the converted image data are used for image formation. At the time of the RIP processing, the RIP processing is performed for print data while reading out print data from the HDD.
Incidentally, in a large-sized image forming apparatus such as a commercial printing apparatus, the large number of paper sheets (staying paper sheets) exists simultaneously in the image forming apparatus during a period after having been subjected to image formation until having been output to the outside. In the case of such an image forming apparatus with the large number of staying paper sheets, in many cases, the image forming apparatus is configured to store image data converted from pint data by RIP processing once in a HDD. Accordingly, a read-out speed at the time of accessing the HDD becomes a factor to determine the productivity of image formation. In other words, an access speed for the HDD becomes “rate limiting” of the productivity of the image forming apparatus.
In order to realize further performance improvement with such constitution, it may be considered to take a measure in association with hardware, such as utilization of a HDD with a RAID constitution (increase of the number of HDDs) so as to improve the HDD performance. Further, also, it may be considered to take a measure in association with hardware, such as reduction of an amount of data to be accessed to a HDD. Furthermore, also, it may be considered to take a measure in association with hardware, such as reduction of an amount of data to be accessed to a HDD and application of hardware so as to perform processing for the reduction.
However, there has been a problem that a solution with a measure in association with hardware directly leads to an increase in a development cost and a production cost.
On the other hand, in an image forming apparatus in a commercial printing system required to have rapidity, in order to increase print productivity, there exists a system configured to process image data in units of a band, not in units of a page. In this case, in order to perform RIP processing in units of a band, image data are needed to be such that color data and attribute data of each pixel in the image data are arranged in a dot sequential format.
In order to reduce hardware cost, some of image forming apparatuses configured to process image data of such a dot sequential format adopt a constitution to compress only color data contained in image data by hardware.
In response to the RIP processing, color data in units of a band are lossily compressed (irreversibly compressed) (Step S14 in
Successively, extension processing is executed for the image data released from the encryption state so as to cancel the compression state (Step S23 in
Japanese Unexamined Patent Publication No. 2010-245976 discloses a technique to separate image data into image blocks and non-image blocks based on attribute data and to compress them appropriately so as to suppress image deterioration. Further, this document discloses a technique to losslessly compress (reversibly compress) attribute data.
However, the above document is silent on the matter that in the case where color date and attribute data are arranged in a dot sequential format, the color date and the attribute data are handled separately from each other so as to be compressed appropriately with good efficiency.
An object of the present invention is to realize a technique to handle image data of a dot sequential format at high speed without increasing the cost of hardware.
(1) An image processing apparatus which reflects one aspect of the present invention is an image processing apparatus for processing image data in which color data and attribute data of each pixel are arranged in a dot sequential format, including an arrangement converting section which separates the color data and the attribute data in the image data and converts arrangement into a face sequential format of a color data group and an attribute data group, and a compressing section which lossily compresses the color data group and losslessly compresses the attribute data group.
(2) In the above (1), the image processing apparatus further includes a RIP processing section which executes Rip processing for image data before RIP (not applied with the RIP processing), the RIP processing section executes the RIP processing in units of a band for the image data which correspond in amount to one page and are divided into multiple bands, and the compressing section repeats lossy compression executed in units of a band for the color data group corresponding in amount to one page and losslessly compresses the attribute data group which is converted in terms of arrangement and corresponds in amount to one page.
(3) In the above (1) to (2), the image processing apparatus further includes a storage section to store data and a control section to control action of each section, and the control section controls such that color data group storage processing to store the lossily-compressed color data group in the storage section and attribute data group compression processing to losslessly compress the attribute data group by the compressing section are executed in parallel to each other.
(4) In the above (1) to (3), the image processing apparatus further includes a storage section to store data and a control section to control action of each section, and the control section controls such that color data group storage processing to store the lossily-compressed color data group in the storage section and attribute data group storage processing to store the losslessly-compressed attribute data group in the storage section are executed in respective different timings from each other.
(5) In the above (1) to (4), the image processing apparatus further includes a storage section to store data, an extending section which lossily extends the lossily compressed color data group and losslessly extends the losslessly compressed attribute data group, and a control section to control action of each section, and in the case where the lossily-compressed color data group and the losslessly-compressed attribute data group are stored with a face sequential format in the storage section, the control section controls such that color data group read-out processing to read out the lossily-compressed color data group from the storage section and attribute data group read-out processing to read out the losslessly-compressed attribute data group from the storage section are executed in respective different timings, and the control section controls the arrangement converting section to convert the arrangement of each of the read-out color data group and the read-out attribute data group into a dot sequential format.
(6) In the above (1) to (5), the image processing apparatus further includes a storage section to store data, an extending section which lossily extends the lossily compressed color data group and losslessly extends the losslessly compressed attribute data group, and a control section to control action of each section, and the control section controls such that color data group read-out processing to read out the lossily-compressed color data group from the storage section and attribute data group extension processing to losslessly extend the losslessly-compressed attribute data group read out from the storage section by the extending section are executed in parallel to each other.
(7) In the above (1) to (6), the image processing apparatus further includes an encrypting section to encrypt data and a control section to control action of each section, and the control section controls such that the color data group is encrypted by the encrypting section after having been lossily compressed by the compressing section and the attribute data group is encrypted by the encrypting section after having been losslessly compressed by the compressing section.
(8) In the above (7), the image processing apparatus further includes a decrypting section to decrypt encrypted data and a control section to control action of each section, and the control section controls such that the color data group is decrypted by the decrypting section before being lossily extended by the extending section and the attribute data group is decrypted by the decrypting section before being losslessly extended by the extending section.
(9) An image forming apparatus which reflects one aspect of the present invention includes the image processing apparatus of the (1) to (4), an extending section which lossily extends the lossily-compressed color data group and losslessly extends the losslessly-compressed attribute data group; a storage section which stores data; a control section which controls operation of each section; and an image forming section which forms an image based on the image data of a dot sequential format; and the control section controls so as to store lossily-compressed color data group and losslessly-compressed attribute data group with a face sequential format in the storage section, to read out the color data group and the attribute data group from the storage section, to lossily extend the read-out color data group by the extending section and losslessly extend the read-out attribute data group by the extending section, to convert arrangement of each of the lossily-extended color data group and the losslessly-extended attribute data group into a dot sequential format by the arrangement converting section, and to form an image based on the image data converted in arrangement into the dot sequential format.
(10) An image forming apparatus which reflects one aspect of the present invention includes the image processing apparatus of the (5) to (8) and an image forming section to form an image based on image data converted in arrangement into a dot sequential format.
Hereinafter, with reference to the drawings, description will be given in detail to a mode (hereafter, referred to embodiment) for implementing the present invention. Herein, description is given to an image forming apparatus 100 as a specific example which can operate as a copier, a scanner, a printer, etc., and has a function to store data.
The image forming apparatus 100 shown in
The control section 101 is constituted to include a CPU (Central Processing Unit) etc., and is configured to control respective sections in the image forming apparatus 100. The communication section 102 is configured to communicate with other apparatuses via various networks and to receive print data (image data before RIP) from other apparatuses. The operation display section 105 is constituted to include a liquid crystal display section and a touch panel, and is configured to allow a user to input an operation.
The scanner section 120 is configured to read documents optically with a light source and a reading element and to produce image data. The image processing section 130 is configured to execute various kinds of image processing, such as RIP processing and compression/extension processing. The storage section 140 is configured to store image data etc. which are handled by the image forming apparatus 100. The print engine 160 is configured to perform image formation with an electrophotographying system etc. based on image data.
The image processing section 130 is constituted to include an image data converting section 131, an arrangement converting section 132, a compressing section 133, an encrypting section 134, a decrypting section 135, and an extending section 136.
Here, the image data converting section 131 is configured to rasterize print data (image data before RIP) described with a page description language by RIP (Raster Image Processor) processing, thereby producing image data of a bit map format. The arrangement converting section 132 is configured to separate color data and attribute data from image data, to convert the respective arrangements of the color data and the attribute data into a color data group and an attribute data group in a face sequential format respectively, and to convert the respective arrangements of the color data group and the attribute data group from the face sequential format to a dot sequential format.
The compressing section 133 is configured to lossily compress a color data group in a lossily compressing section and to losslessly compress an attribute data group in a losslessly compressing section. The encrypting section 134 is configured to encrypt data by using various kinds of encrypting algorithms. The decrypting section 135 is configured to decrypt the encrypted data. The extending section 136 is configured to lossily extend a compressed color data group in a lossily extending section and to losslessly extend a compressed attribute data group in a losslessly extending section.
Herein, when storage processing is executed on one side of later-mentioned parallel processing and the compressing section 133 executes lossless compression on another side of the parallel processing, the load of the CPU in the storage processing is small. For this reason, it is possible for the CPU to perform the lossless compression in accordance with software. Therefore, it is possible to cope with the lossless compression by the software without providing hardware used only for the lossless compression.
The storage section 140 is constituted to include a storage control section 141, an image memory 142 as a volatile storage section, and a HDD 143.
Herein, the storage control section 141 is configured to control storage of data in the storage section 140. The image memory 142 is a volatile storage section, and stores the image data of a page for image formation in a semiconductor memory, such as DDR_SDRAM. The HDD 143 stores a large amount of image data as a nonvolatile storage section.
In the embodiment shown in
With regard to encryption processing, decryption processing, compression processing, and extension processing, it is possible to use various kinds of known methods. For this reason, with regard to the encryption processing, the decryption processing, the compression processing, and the extension processing, methods should not be limited to a certain specific method.
Herein, description is given to the first half of the operation of image formation in the present embodiment. In the following description, description on general operation as the image forming apparatus 100 is omitted, and description is given with reference to a flow chart shown in
The image processing section 130 receives print data (image data before RIP) transmitted from an external device via the communication section 102 (Step S101 in
Herein, print data and image data in this embodiment are constituted with a dot sequential format. The dot sequential format means a format that color data and attribute data are arranged alternately for each pixel.
As shown in
Further, as shown in
Further, in this embodiment, at the time of storing image data, the arrangement of the image data of the dot sequential format are converted into image data of a face sequential format. Herein, the face sequential format means a format that color data (face data) corresponding in amount to one page and attribute data (face data) corresponding in amount to one page are arranged alternately.
As shown in
The print data received in the image processing section 130 are divided into units of a band, and are sent to the image data converting section 131. The print data divided into units of a band are rasterized by RIP processing in the image data converting section 131 and are converted into image data of a bit map format (Steps S102 and S103 in
At this time, the color data are lossily compressed by the compressing section 133 (Step S105 in
Successively, the arrangement of the image data is converted by the arrangement converting section 132 such that the image data of the dot sequential format (refer to FIG. 3 and
Subsequently, the encryption processing for the color data group is executed by the encrypting section 134 (color data group encryption processing: Step S108 in
Further, when the above color data group encryption processing and color data group storage processing are performed, the following attribute data group compression processing and attribute data group storage processing are executed as parallel processing. That is, the attribute data group is losslessly compressed by the compressing section 133 (attribute data group compression processing: Step S110 in
Further, in the above-mentioned parallel processing, it is more preferable that the color data group storage processing (Step S109 in
In this case, during execution of the color data group storage processing (Step S109 in
Similarly, in the parallel processing, it is preferable that the color data group storage processing (Step S109 in
In this case, during execution of the color data group storage processing (Step S109 in
Further, in the parallel processing, it is preferable that the color data group storage processing (Step S109 in
In this case, the timing of the color data group storage processing (Step S109 in
Further, as mentioned above, during execution of the color data group storage processing (Step 5109 in
Further, in the above specific example, the color data group is encrypted after being lossily compressed, and the attribute data group is encrypted after being losslessly compressed. Herein, if encryption is executed prior to compression, the value of data is rewritten, whereby continuity is no longer maintained. As a result, good efficient compression is not executed. Namely, as mentioned above, the encryption processing of the color data group and the encryption processing of the attribute data group are executed after respective compression, whereby the color data group and the attribute data group have the continuity of data in a given range respectively. Accordingly, good efficient compression can be attained. As a result, it becomes possible to handle the image data of the dot sequential format at high speed without increasing the cost of hardware.
Herein, description is given to the latter half of the operation of image formation in the present embodiment. In the following description, description on general operation as the image forming apparatus 100 is omitted, and description is given with reference to a flow chart shown in
First, the attribute data group applied with the lossless compression processing and the encryption processing is read out from the HDD 143 (Step S201 in
The read-out color data group is applied with decryption processing by the decrypting section 135 so as to be released from the encryption state (color data group decryption processing: Step S205 in
Further, in the parallel processing, it is preferable that the color data group read-out processing (Step S202 in
That is, since all the data (both the color data and the attribute data) do not concentrate on each of the read-out processing and the extension processing, the read-out processing and the extension processing can be executed promptly without any waste. Accordingly, it becomes possible to handle the image data of the dot sequential format at high speed without increasing the cost of hardware.
Similarly, in the parallel processing, it is preferable that the color data group read-out processing (Step S202 in
Further, in the processing in this embodiment, it is preferable that the attribute data group read-out processing (Step S201 in
Further, as mentioned above, during execution of the color data group read-out processing (Step S202 in
Further, in the above specific example, since the data group is encrypted after being compressed, the color data group is decrypted before being lossily extended, and the attribute data group is decrypted before being losslessly extended. In this way, each of the decrypting operation of the color data group and the decrypting operation of the attribute data group is executed before the extending operation. Accordingly, it becomes possible to extend the compressed color data group and the compressed attribute data in a good efficient state after the decryption operation. In this case, the color data group is compressed before the encryption processing, and the attribute data group is compressed before the encryption processing. Accordingly, the color data group and the attribute data group in a state of having the continuity of data within a given range can be compressed with good efficiency. That is, since the data size at the time of decryption is also controlled, it becomes possible to execute high speed processing without increasing the cost of hardware.
Further, in the above specific example, at the time of processing image data arranged in the dot sequential format, the lossily compressed color data group and the losslessly compressed attribute data group are stored with the face sequential format in a HDD 143. Subsequently, the color data group and the attribute data group are read out from the HDD 143. Then, the read-out color data group is lossily extended, and the read-out attribute data group is losslessly extended. Successively, the lossily extended color data group and the losslessly extended attribute data group are converted in arrangement to the dot sequential format. Thereafter, an image is formed based on the image data converted in arrangement to the dot sequential format. Thus, the image data of the dot sequential format are processed by arrangement conversion, compression, storage, extension, and arrangement conversion. Accordingly, it becomes possible to perform image formation while handling the image data of the dot sequential format at high speed without increasing the cost of hardware.
In the above-described “[B] Operation (storage processing) in the image forming apparatus”, the color data group and the attribute data group are stored in the HDD 143 after being applied with the encryption processing. However, the present invention should not be limited to the above specific example. For example, in the case where image data not having confidentiality are handled, or in the case where a possibility that image data flow out from the image forming apparatus 100 is very small, the encryption processing is unnecessary.
In such a case, the respective steps described in the flow chart shown in
In parallel processing in this case, the color data group storage processing (Step S109 in
Further, in parallel processing in this case, the color data group storage processing (Step S109 in
In the above-described “[C] Operation (read-out and image formation processing) in the image forming apparatus”, after the color data group and the attribute data group are applied with the decryption processing, extension processing is executed. However, the present invention should not be limited to the above specific example. For example, in the case where image data not having confidentiality are handled, or in the case where a possibility that image data flow out from the image forming apparatus 100 is very small, if the encryption processing is omitted, the decryption processing is also unnecessary.
In such a case, the respective steps described in the flow chart shown in
In parallel processing in this case, the color data group read-out processing (Step S202 in
Further, in processing in this case, the attribute data group read-out processing (Step S201 in
In the description of each of the above embodiments, while adopting the rule in parallel processing with the same timing or processing with different timings, it is also possible to make modification such as insertion of other processing which is not described here. Also in such a case, each processing can be executed promptly without any waste. Accordingly, it becomes possible to handle the image data of the dot sequential format at high speed without increasing the cost of hardware.
Further, in the above description, the control section 101 in the image forming apparatus 100 is configured to adjust the timing of each processing. The present invention should not be limited to this example. For example, the processing timing may be controlled from external apparatuses via a network.
Further, even in the case where an image processing apparatus exists solely so as to make the image processing section 130 as the center, not as the image forming apparatus 100, similarly to the above-mentioned embodiments, it becomes possible to handle the image data of the dot sequential format at high speed without increasing the cost of hardware.
Number | Date | Country | Kind |
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2014-178304 | Sep 2014 | JP | national |