JP4074832B2 - Data processing method and data processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for decompressing a data string compressed by the JPEG method or the like.
[0002]
[Prior art]
In recent years, an image taken by a digital camera can be stored as a data string compressed by the JPEG method. The data group compressed by the JPEG method can be stored in a personal computer, uploaded to a website, decompressed via a browser, and released as an image. It is also possible to create data for printing by expanding a data group compressed by the JPEG method, and thereby print out an image.
[0003]
According to the JPEG method, an image is divided into a plurality of matrices (pixel regions or pixel blocks), and information forming individual pixel regions, that is, pixel data is entropy coding (also referred to as variable length coding). It is compressed by the Huffman method. Therefore, a data set in which pixel data for each data pixel area for storing image data is compressed is called a minimum encoding unit (MCU), and an image file compressed by the JPEG method has A plurality of MCUs are stored side by side in the scan direction.
[0004]
[Patent Document 1]
JP 2000-278865 A
[0005]
[Problems to be solved by the invention]
In the JPEG method, since the image data is compressed using variable length coding, the amount of data can be greatly reduced, and it is suitable for storing image data and transmitting image data. On the other hand, when trying to access information in the middle of image data, there is a problem that the MCU must be expanded or decoded in order from the beginning. Since the pixel data is variable-length encoded and then arranged in the scan direction, the size of each encoded MCU is different. For this reason, unless it decodes in order from the head MCU, the head or the end of each MCU cannot be grasped.
[0006]
Therefore, when a situation occurs in which an MCU is desired to be used in an order that does not match the MCU order for a data group compressed by the JPEG method, the processing of the data group compressed by the JPEG method becomes more troublesome. Become. For example, when printing an image, if the head is moved from the top of the image in the scan direction in which the MCUs are arranged and printed, the MCU can be expanded in order, but the direction different from the scan direction, for example, the scan direction In the case of printing in the sub-scan direction orthogonal to or from the end reverse in the scan direction, it is necessary to prepare dot matrix data representing a two-dimensional image by decoding all the MCUs in advance. For this reason, a large-capacity memory capable of holding an enormous amount of data is required, or the image data cannot be transmitted to the printer in a compressed state, so there is no merit of compressing the image data by the JPEG method.
[0007]
Japanese Patent Laid-Open No. 2000-278685 describes that position information relating to a specified image area is stored as a pre-scan table by sequentially decoding a data sequence compressed by the JPEG method from a start position by a pre-scanner. Has been. Once the prescan operation has been performed, the image area can be accessed directly, so sequential scanning is required for any encoded image area whose position information is stored in the prescan table by the prescanner. It is stated that it will not.
[0008]
This processing method does not need to decompress the entire JPEG data in advance and store the dot matrix of the entire image in the memory, so printing can be performed even with a small memory capacity, and the advantages of the JPEG method are maintained. it can. However, a new pre-scan table needs to be created and stored in the memory in order to store the position information. Therefore, in addition to the data compressed by the JPEG method, a memory having a capacity for storing the pre-scan table is required at a minimum. Japanese Patent Laid-Open No. 2000-278585 describes that the amount of storage device required for the pre-scan table is reduced by storing position information relating to an area smaller than all of the image areas. However, since the position information must be stored in order to directly access the image area, the memory capacity allocated to the pre-scan table cannot be reduced to zero.
[0009]
Furthermore, this processing method must reference a pre-scan table to directly access the image area. That is, for an encoded image area whose position information is not stored in the pre-scan table, sequential scanning with decompression work must be performed in order to access the image area. Therefore, if the position information stored in the pre-scan table is reduced in order to save the memory capacity allocated to the pre-scan table, the processing speed decreases.
[0010]
Accordingly, an object of the present invention is to provide a data processing method capable of processing data compressed using entropy coding as in the JPEG method at a high speed with a small amount of memory. Further, a program and a data processing apparatus capable of realizing such a data processing method, and a printer are provided, so that data compressed using entropy coding can be flexibly processed with a smaller capacity memory. The purpose is to be.
[0011]
[Means for Solving the Problems]
Therefore, in the present invention, paying attention to the fact that a data group is composed of a compressed data set for each pixel area, the entire compressed data is expanded (or expanded) for flexible processing. Instead, each compressed data set is compressed as it is, the order is detected, and the data sets are rearranged, thereby enabling flexible processing. Therefore, according to the present invention, in order to perform processing in an order different from that of the original data array, a memory having a capacity enough to expand the entire image data is unnecessary, and the position information of each data set is stored. No extra table is required.
[0012]
That is, according to the data processing method of the present invention, an image is divided into a plurality of pixel areas, and a plurality of compressed data sets obtained by compressing pixel data included in each pixel area using at least entropy coding is a first array. Each of the compressed data sets is sequentially detected from the arranged first data group, and has a rearrangement step for generating the second data group by arranging in a second array different from the first array. Each compressed data set has difference information depending on the first array, and the rearrangement step detects each compressed data set in order according to the first array and depends on the first array. Obtaining a value obtained by accumulating the difference information, and each compressed data set and a value obtained by accumulating the difference information corresponding to each compressed data set in the order according to the second array Alternating By using this rearrangement step, including generating a second data group so that the first data group is received, the respective compressed data sets detected in sequence when the first data group is received The second data group can be formed by outputting the data to a transfer destination for forming the two arrays, for example, an appropriate memory address. Therefore, the contents of the original first data group can be preserved only by storing the second data group in which the compressed data sets are arranged in the second arrangement suitable for the subsequent processing in a recording medium such as a memory. It becomes possible. For this reason, it is not necessary to expand the entire original first data group in the memory for subsequent processing. In addition, there is a trouble of storing the first data group in the memory, detecting the position information thereof, separately creating and storing a table including the position information, and an extra memory capacity necessary for storing the table. It can be omitted.
[0013]
Therefore, when the data processing method of the present invention includes a step of outputting a plurality of compressed data sets included in the second data group in accordance with the second sequence following the rearrangement step, Processing can be executed simply by accessing the data group according to the array. Therefore, according to the present invention, it is possible to prevent the occurrence of the problem that the compressed data set included in the data group must be directly accessed based on the position information of the compressed data set. In the present invention, since the compressed data set is stored in a compressed state, it is possible to prevent an increase in memory capacity and an increase in processing time spent for expanding all the compressed data in advance. The desired processing can be performed in a short time with economical hardware.
[0014]
Therefore, the present invention also provides a program or program product and a data processing apparatus that can execute the data processing method of the present invention. That is, the program of the present invention divides an image into a plurality of pixel areas, and a plurality of compressed data sets obtained by compressing pixel data included in each pixel area using at least entropy coding are arranged in a first array. An instruction capable of executing in a computer a rearrangement step of generating a second data group by sequentially detecting each compressed data set from the first data group and arranging the compressed data sets in a second array different from the first array Have This program can be recorded on an appropriate recording medium or provided via a computer network. Further, in the rearrangement step, a second process is performed by executing a process of outputting each compressed data set detected in order from the first data group received by the computer to a transfer destination for forming the second array. Data groups can be generated, and the memory managed by the computer can be used more effectively. The computer includes a processor such as a CPU mounted on the peripheral device to control the peripheral device such as a printer, in addition to a personal computer that operates alone. The program can include an instruction for executing a process of decompressing and outputting a plurality of compressed data sets included in the second data group according to the second array.
[0015]
In the data processing apparatus of the present invention, a plurality of compressed data sets obtained by dividing an image into a plurality of pixel regions and compressing pixel data included in each pixel region using at least entropy coding are in a first array. Each of the compressed data sets is sequentially detected from the arranged first data group, and rearrangement means for generating a second data group by arranging in a second array different from the first array. Each compressed data set has difference information depending on the first array, and the rearrangement means detects each compressed data set in order according to the first array and depends on the first array. The partial decompression function for obtaining the accumulated value of the difference information, each compressed data set, and the value obtained by accumulating the difference information corresponding to each compressed data set in the order according to the second array Alternating And a transfer function for generating the second data group. The rearrangement means may generate the second data group by receiving the first data and outputting each compressed data set detected in order to a transfer destination for forming the second array. it can. Further, the data processing apparatus can include means for expanding and outputting a plurality of compressed data sets included in the second data according to the second array.
[0016]
One very useful application form of the data processing method of the present invention is printing. That is, the present invention provides a printing method including the above-described rearrangement step and the step of printing a plurality of compressed data sets included in the second data group by expanding and printing in accordance with the second arrangement. Also provided is a printing apparatus having rearrangement means and means for expanding and printing a plurality of compressed data sets included in the second data according to the second arrangement.
[0017]
In the above-described JPEG system and MPEG system having a similar compression structure, each compressed data set may include differential information depending on the first arrangement of the original first data group. is there. For example, in the JPEG system, each compressed data set is such that pixel data included in a pixel area of a two-dimensional image is compressed by at least discrete cosine transform, quantization, and Huffman coding, and further, a quantized discrete data set The value of cosine coefficient is included as difference information. Therefore, when the compressed data set is rearranged in a second array different from the first array, the included difference information may not be used as it is. Therefore, in the rearrangement step and the rearrangement means, each compressed data set is detected in order and the absolute value of the difference information corresponding to each compressed data set is obtained, and a plurality of compressed data sets and their corresponding absolute values are obtained. It is desirable to generate a second data group in which values are included according to the second array. When the compressed data set is compressed by the JPEG method or a similar method, the rearrangement step and the rearrangement unit obtain the absolute value of the discrete cosine coefficient corresponding to each compressed data set, and a plurality of compressed data sets It is desirable to generate the second data group in which the absolute values of the discrete cosine coefficients corresponding thereto are included in the second array.
[0018]
In an example of the present invention, when the first data group includes a plurality of compressed data sets in the first array mainly in the scan direction of the two-dimensional image, the rearrangement step and the rearrangement unit A second data group including a plurality of compressed data sets is generated in a second array mainly in the sub-scan direction of the two-dimensional image. It is effective when printing in the sub-scan direction, and a printer capable of high-speed printing with a small-capacity memory using JPEG-compressed data can be provided at low cost. External storage devices such as memories and disks occupy a large proportion of the cost of the components that make up the product, and reducing the storage capacity has a great economic effect.
[0019]
The second arrangement is not limited to the above, and can be arranged in the direction opposite to the scanning direction, or a part of the first arrangement can be extracted to form the second arrangement. Various sequences suitable for processing can be selected as the second sequence.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an outline of a printer provided with a data processing apparatus of the present invention. The printer 1 acquires a data string or data group (hereinafter referred to as JPEG data or first data group) φ1 compressed by the JPEG method from a peripheral device such as a digital camera or a host device such as a personal computer, and decompresses it. Print. The first data group φ1 includes an interface capable of reading storage such as a compact flash (registered trademark) and a memory stick (registered trademark), or a communication interface 11 such as a USB that enables communication with a host device and peripheral devices. Via the printer 1.
[0021]
The printer 1 includes a print head 4 having a plurality of nozzles 3 for ejecting ink droplets onto a print paper 2 and a motor for reciprocating the print head 4 along a shaft 5 with the paper width direction as a scan direction during printing. 6 and a motor 8 for driving the roller 7 to feed the printing paper 2 in the paper feeding direction perpendicular to the scanning direction at the time of printing. Further, the printer 1 has a control unit 10 constituted by a CPU, a RAM, a ROM, and the like, and the timing at which ink droplets are ejected from the motors 6 and 8 and the nozzle 3 is controlled by the control unit 10.
[0022]
When receiving the first data group φ1, the control unit 10 receives the plurality of compressed data sets included in the first data group φ1 in the first array, that is, the MCU in the JPEG format, The data receiving unit 22 stores the data in the RAM 12 as the second data group φ10. In the first data group φ1, when the MCUs are arranged in the image scanning direction X (first arrangement), the data receiving unit 22 arranges the MCUs in the printing scanning direction Y (second arrangement). The second data group φ10 is converted and stored in the RAM 12. As a result, the printer 1 simply prints the image given by the first data group φ1 in the scanning direction of the printer by expanding and printing the MCUs included in the second data group φ10 in that order. can do. That is, in the printer 1 of this example, the sub-scan direction Y of the two-dimensional image is the scan direction when printing, and hereinafter, the scan direction X of the data row φ1 will be described as a reference scan direction.
[0023]
More specifically, the control unit 10 of this example includes a data processing unit 20 that processes print data, and a mechanism control unit that controls the motors 6 and 8 and the head 4 based on the processed data to print out the data. 21. The data receiving unit 22 of this example included in the data processing unit 20 detects the order of a plurality of MCUs included in the first data group φ1 supplied from the interface 11, and each MCU is placed in the second array. In this way, it functions as a rearrangement unit that transfers to a predetermined address in the RAM 12 and changes the arrangement order of the MCUs to generate the second data group φ10. Further, the data processing device 20 includes an output unit 25 that sequentially expands and outputs the MCU based on the second data group φ10 recorded in the RAM 12.
[0024]
JPEG (Joint Photographic Cording Experts Group), which is one of the compression methods, has the information of the dot matrix forming one image from the left side to the right side, and from top to bottom, that is, from top left to bottom right. The pixel area or pixel block of 8 dots × 8 dots is divided and compressed and stored as MCU in units of the pixel area. The unit of the dot matrix that forms the image is not limited to 8 dots × 8 dots, but the divided small matrix is used as one pixel block to form one compressed data set (MCU), and a plurality of compressed data sets are provided. The image scan direction, that is, a group of images arranged in order from the upper left to the lower right, becomes an aggregate, and becomes JPEG data obtained by compressing one image. This is the first data group in this example.
[0025]
The process of compressing an image by the JPEG method will be described a little more. First, the dot matrix forming the image is converted from the primary color system (RGB) color space of the image data to pixel data of the color difference system (YCbCr) color space. Next, the pixel data is divided into 8-dot × 8-dot pixel blocks, and the pixel data converted in units of blocks is subjected to discrete cosine transform (DCT). Furthermore, the DCT coefficient obtained at the time of discrete cosine transform is quantized using a quantization table. The quantized DCT coefficient is further compressed using a Huffman code which is one of entropy coding or variable length coding. At the time of Huffman encoding, of the DC component and AC component of the quantized DCT coefficient, the DC coefficient (component) is encoded as a difference value with respect to the DC coefficient of the immediately preceding pixel block. For this reason, when decoding the data string φ1, the decompression process such as Huffman decoding, inverse quantization, inverse DCT, and RGB conversion is performed in reverse order when the data compressed by the MCU is compressed. Is expanded into two-dimensional image data.
[0026]
In the data group φ1 compressed by the JPEG method, since each MCU is variable-length encoded, each MCU has a different size. Therefore, each MCU cannot be identified without Huffman decoding. In other words, if Huffman decoding is performed, each MCU can be detected or identified without executing all the decompression processes including inverse quantization and inverse DCT. Therefore, the data receiving unit 22 includes a partial decompression function 23 that detects each MCU while performing Huffman decoding in order from the head of the received data group φ1, and a RAM 12 that forms the detected MCU in a second array. Is provided with a transfer function 24 for outputting to the address. Therefore, when the data receiving unit 22 receives all the first data groups φ1 and stores the data in the RAM 12, the RAM 12 forms the second data group φ10 in which the MCUs are arranged in the second array and the order is changed. Is done.
[0027]
In the data receiving unit 22 of this example, the first data group φ1 is not stored in the RAM 12, and the Huffman decoding is performed when the MCU is detected, but the Huffman decoding is performed before the Huffman decoding. The MCU in the state is stored in the RAM 12. Therefore, the RAM 12 can record the second data group φ10 if it has a capacity sufficient to record the MCU included in the data group φ1. Therefore, the rearranged second data group φ10 can be stored by a memory having a capacity enough to store the original data group φ1. Actually, as shown below, since the absolute value of the DC coefficient of each MCU is stored correspondingly, a memory area is consumed a little extra.
[0028]
As described above, the DC coefficient is included in the MCU as difference information. Therefore, when the data is rearranged in the second array, the information cannot be used as it is. For this reason, the partial expansion function 23 of the data receiving unit 22 obtains DC coefficients represented as differential information of each MCU by partial expansion, so that they are cumulatively calculated and the DC coefficients up to the previous MCU are calculated. Find the absolute value. Further, the output function 24 transfers the absolute value of the DC coefficient together with the MCU to the RAM 12 and stores them in association with each other. Thereby, even in the second data group φ10 in which the MCUs are arranged in the second array, the MCUs can be expanded in order.
[0029]
FIG. 2 shows how the second data group φ10 is generated by the data receiver 22 of this example. In this example, a plurality of MCUs included in the first data group φ1 in the scan direction X in order are rearranged in the sub-scan direction Y to generate the second data group φ10. When the partial decompression function 23 detects MCU1 included in the first data group φ1, the transfer function 24 transfers MCU1 to the head address of the area 12a in the column 0 of the RAM 12. At the same time, the absolute value φ12 of the DC coefficient accumulated so far is transferred so as to be recorded after MCU1. The absolute value φ12 may be recorded first. Next, when the next MCU 2 is identified by the partial decompression function 23, the transfer function 24 transfers the MCU 2 to the start address of the area 12 b of the next column 1 of the RAM 12. At the same time, the absolute value φ12 in which the difference information up to MCU1 is accumulated is transferred so as to be recorded after MCU2. When the process of receiving the first data φ1 proceeds and the MCU 17 is identified by the partial decompression function 23, the MCU 17 is arranged next to the MCU 1 in the sub-scan direction Y, so the transfer function 24 sets the MCU 17 to 1 Transfer to the address after MCU1 in area 12a of column 0. Thus, by repeating the process of receiving the first data φ1 and storing it in the RAM 12, the RAM 12 stores the second data group φ10 in which MCUs are arranged in the sub-scan direction Y.
[0030]
The output unit 25 of the data processing unit 20 can start the process when the data row φ13 of one column in the sub-scan direction Y of the second data group φ10 is recorded at least in the column 12 area 12a of the RAM 12. . Each of the MCU1, MCU17, MCU33, MCU49, MCU65, MCU81, MCU97, MCU113, MCU129, and MCU144 that constitute the leftmost sub-scan direction Y of the scan direction X of the two-dimensional image corresponds to the memory area 12a of the column 0. When recorded as a pair with the DC absolute value φ12, data φ13 for one column in the scanning direction Y for printing is generated. Therefore, the output unit 25 expands the MCU included in the data string φ13, sends it to the mechanism control unit 21 as print data, and starts printing. In this example, in accordance with the movement of the print head 4, the output unit 25 sequentially expands the MCU of the data string φ 13 recorded in the memory area 12 a of column 0 from the end toward the beginning, Applicable print data can be output. If the printer 1 can use a memory area that only stores the print data for the line on which the print head 4 moves, the MCU of the data string φ13 may be expanded in order from the top. In any case, in the output unit 25, each MCU is not expanded in the same order as recorded in the first data group φ1, but Huffman decoding is possible, and thereafter, it is recorded together with the MCU. By using the absolute value φ12 of the DC coefficient, it is possible to expand all the MCUs through the entire process of expansion processing of inverse quantization, inverse DCT, and RGB conversion.
[0031]
FIG. 3 shows an outline of a process from reception of the first data group φ1 to printing in the printer 1 of the present example, using a flowchart. In step 41, if there is a first data group φ1 to be received, in step 42, only the Huffman decoding is performed by the partial decompression function 23 of the data receiving unit 22, and the MCUs included in the first data group φ1 are sequentially selected. To detect. In step 42, the absolute value φ12 of the DC coefficient is also calculated. When the MCU is detected, the transfer destination (address of the RAM 12) of the detected MCU is set in step 43, and the detected MCU and the absolute value φ12 of the DC coefficient are transferred to the RAM 12 in step 44. In step 41, the second data φ10 in which the MCUs are rearranged is generated in the RAM 12 by repeating until the first data group φ1 to be received is completed, so that printing is performed when reception is completed or even during reception. When the possible data string φ13 is prepared, in step 47, the output unit 25 expands the MCU according to the rearranged second array and prints it in step 48.
[0032]
These processes can be provided as a program having instructions executed by the processor or microcomputer such as the CPU or ASIC constituting the control unit 10 of the printer 1 in the above steps. This program can be provided by being stored in the ROM 19 as the firmware 18 of the printer 1 and used. Further, the program can be provided via a computer network such as the Internet and installed in the printer 1 for use. Each of the above steps can also be realized by hardware logic, and a processor equipped with such hardware logic can be adopted as the control unit 10. It is also possible to execute part of the processing by hardware and the rest of the processing by software.
[0033]
In this way, in the printer 1 having the data processing device 20 that can rearrange the MCUs included in the first data group φ1 into an appropriate second array and store it as the second data group φ10, the second data group φ10 If the memory capacity is sufficient, the MCU can be expanded and printed in a flexible order regardless of the order of the MCUs included in the first data group φ1 compressed by the JPEG method. In the above example, a plurality of MCUs arranged in the scan direction X of the two-dimensional image can be printed in the sub-scan direction Y. Since the second data group φ10 includes MCUs that remain in a compressed state, it is sufficient if there is almost the same memory area as the original JPEG data φ1 is stored. The memory area for storing the position information of φ1 and each MCU is not necessary, and the resources for data storage may be very small.
[0034]
Furthermore, after the data is received, the process can proceed based on the arrangement of the MCUs included in the second data group φ10 generated in the RAM 12, so there is no need to access the MCUs randomly based on the position information. . Therefore, in order to execute subsequent processing such as printing, hardware resources that can execute processing such as random access to each MCU stored in the RAM 12 based on position information at high speed are not required. . Further, in the processing after the data is received, the MCU can be referred to in the necessary order. Therefore, the processing after the Huffman decoding may be performed each time. For this reason, the capacity of the storage device required only for the data processing after development may be very small, and the capacity of the storage device mounted on the printer 1 can also be reduced in this respect. A small-capacity memory device can also be configured in a microprocessor chip, so that the effect of reducing the number of parts can be obtained and the cost can be reduced. In addition, when a memory device is installed inside the processor, it can be made a memory that can operate on a wide range of high-speed buses within the processor, so it is possible to provide a printer that operates at high speed using an inexpensive processor that does not have cache memory. It becomes.
[0035]
In addition, since it is possible to obtain an effect that the memory capacity used for processing the JPEG data φ1 is small, the present invention is not limited to a printer. The present invention is suitable for handling data compressed by the JPEG method or the MPEG method employing a similar compression algorithm.
[0036]
FIG. 4 shows an example in which the rearranged data string φ10 is transmitted from the portable terminal 50 to the printer 1a and printed. In the terminal 50, an application 51 capable of image processing such as a browser is running, and the JPG data φ1 can be downloaded from the Internet 59 and displayed. When printing an image from the application 51, the printer driver 53 converts the MCU included in the first data group φ1 compressed by the JPEG method into a second array suitable for printing by the printer 1a, and converts the memory 52 The data receiving part 56 memorize | stored in is provided. Then, the second data φ10 in which the MCUs are arranged in the second array is generated in the memory 52 as a spool file, which is supplied as print data from the printer driver 53 to the printer 1a. The data receiving unit 56 of the printer driver 53 also includes a partial decompression function 54 that detects the MCU by partially decompressing (Huffman decoding) the first data string φ1 received via the Internet 59 and the LAN interface 58. And a transfer function 55 for rearranging the MCUs arranged in a print array. In the printer 1a, the second data group φ10 in which MCUs are arranged in an array suitable for printing is received by the data receiving unit 29 and stored in the memory 12. Then, it is decompressed and output by the output unit 25.
[0037]
The data sequence compressed by the JPEG method includes hierarchically encoded data including DHP (Define Hierarchical Progression) and data in a format in which no DHP marker is inserted. The present invention is applicable to any data. Is possible. In addition to processing of a data group compressed by the JPEG method, a two-dimensional image such as an MPEG method is divided into a plurality of matrices, and each matrix becomes one pixel block, and pixels included in the pixel block The present invention can be applied when a compressed data set in which data is compressed at least by entropy coding (variable length coding) processes a first data group arranged in a first array.
[0038]
In the above description, the ink jet type printers 1 and 1a have been described as examples. However, a thermal type or laser type printer may be used. Furthermore, the present invention can be applied to a line type printer without being limited to the type that prints while moving or scanning the print head 13. The printer is a concept including all devices having a printing function such as facsimile and copying. Furthermore, the present invention can be applied not only to the printing process but also to a process of displaying images on the screen in an order different from the compressed order.
[0039]
【The invention's effect】
As described above, in the present invention, a plurality of compressed data sets included in the first data group compressed by the JPEG method or the like are detected in order, and these compressed data sets are rearranged in a different order. A second data group is formed. Therefore, only the arrangement is changed while the compressed data set is compressed, and the present invention allows flexible in a different order from the original data group without increasing the capacity for storing the data group. In addition, a desired compressed data set can be accessed at high speed without generating extra processing.
[0040]
Therefore, by applying the present invention to a printer, a printer capable of printing JPEG data in various orders with a small amount of memory can be provided at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a printer equipped with a data processing apparatus of the present invention.
FIG. 2 is a diagram illustrating a state in which the arrangement of a plurality of MCUs in a data string is changed by a rearrangement unit of the data processing device.
FIG. 3 is a flowchart showing a printing process in the printer shown in FIG. 1;
FIG. 4 is a diagram illustrating an example in which rearrangement of data strings is performed by an external device.
[Explanation of symbols]
1, 1a Printer
4 Print head
12 RAM
20 Data processing device
22 Rearrangement part
23 Partial extension function
24 Transfer function
25 Output section
φ1 First data group
φ10 2nd data group
X Scan direction
Y Sub-scan direction

Claims (14)

The image is divided into a plurality of pixel regions, and each of the first data group in which a plurality of compressed data sets in which pixel data included in each pixel region is compressed using at least entropy coding are arranged in a first array A reordering step of detecting a compressed data set in sequence and generating a second data group by arranging in a second array different from the first array;
Each compressed data set includes difference information depending on the first array,
The rearrangement step detects each of the compressed data sets in order according to the first array, and obtains a value obtained by accumulating difference information dependent on the first array;
The second data group is arranged such that each of the compressed data sets and a value obtained by accumulating the difference information corresponding to each of the compressed data sets are alternately arranged in the order according to the second array. Generating a data processing method.   2. The data processing according to claim 1, wherein in the rearrangement step, the first data group is received, and each of the compressed data sets detected in order is output to a transfer destination for forming the second array. Method. According to claim 1 or 2, further data processing method having the step of outputting the plurality of compressed data sets included in the second data group extends in accordance with the second sequence. In any one of claims 1 to 3, wherein the first data group, the scanning direction of the two-dimensional image includes a plurality of compressed data sets arranged in order of the first sequence to the main ,
The data processing method, wherein the second data group includes the plurality of compressed data sets arranged in the order of the second arrangement mainly in a sub-scan direction of a two-dimensional image. In any one of claims 1 to 4, each said compressed data set is two-dimensional the pixel data included in the pixel area are at least discrete cosine transform of an image are compressed by the quantization and Huffman coding, the difference information includes the value of the quantized DCT coefficients, the data processing method. 6. The data processing method according to claim 1, wherein the compressed data set is compressed by a JPEG method. The image is divided into a plurality of pixel regions, and each of the first data group in which a plurality of compressed data sets in which pixel data included in each pixel region is compressed using at least entropy coding are arranged in a first array A rearrangement step of detecting a compressed data set in sequence and generating a second data group by arranging in a second array different from the first array;
Extending and printing the plurality of compressed data sets included in the second data group according to the second array;
Each compressed data set comprises difference information dependent on the first array;
The rearrangement step detects each of the compressed data sets in order according to the first array, and obtains a value obtained by accumulating difference information dependent on the first array;
The second data group is arranged such that each of the compressed data sets and a value obtained by accumulating the difference information corresponding to each of the compressed data sets are alternately arranged in the order according to the second array. Generating a printing method. The image is divided into a plurality of pixel regions, and each of the first data group in which a plurality of compressed data sets in which pixel data included in each pixel region is compressed using at least entropy coding are arranged in a first array A program having instructions capable of executing in a computer a rearrangement step of detecting a compressed data set in order and generating a second data group by arranging in a second array different from the first array,
Each compressed data set comprises difference information dependent on the first array;
The rearrangement step detects each of the compressed data sets in order according to the first array, and obtains a value obtained by accumulating difference information dependent on the first array;
The second data group is arranged such that each of the compressed data sets and a value obtained by accumulating the difference information corresponding to each of the compressed data sets are alternately arranged in the order according to the second array. Generating a program. 9. The rearrangement step according to claim 8 , wherein each of the compressed data sets detected in order from the first data group received by the computer is output to a transfer destination for forming the second array. A program that performs processing. 10. The program according to claim 8 or 9, further comprising instructions that allow the computer to further execute a step of decompressing and outputting the plurality of compressed data sets included in the second data group according to the second array. The image is divided into a plurality of pixel regions, and each of the first data group in which a plurality of compressed data sets in which pixel data included in each pixel region is compressed using at least entropy coding are arranged in a first array Reordering means for detecting a compressed data set in order and generating a second data group by arranging in a second array different from the first array;
Each compressed data set comprises difference information dependent on the first array;
The rearrangement means detects each of the compressed data sets in order according to the first array, and a partial decompression function for obtaining a value obtained by accumulating difference information dependent on the first array;
The second data group is arranged such that each of the compressed data sets and a value obtained by accumulating the difference information corresponding to each of the compressed data sets are alternately arranged in the order according to the second array. A data processing apparatus including a transfer function to be generated. 12. The data processing apparatus according to claim 11 , wherein the rearrangement unit receives the first data and outputs each of the compressed data sets detected in order to a transfer destination for forming the second array. . 13. The data processing apparatus according to claim 11 , further comprising means for expanding and outputting the plurality of compressed data sets included in the second data according to the second array. The image is divided into a plurality of pixel regions, and each of the first data group in which a plurality of compressed data sets in which pixel data included in each pixel region is compressed using at least entropy coding are arranged in a first array Reordering means for detecting a compressed data set in order and generating a second data group by arranging in a second array different from the first array;
Means for expanding and printing the plurality of compressed data sets included in the second data group according to the second array;
Each compressed data set comprises difference information dependent on the first array;
The rearrangement means detects each of the compressed data sets in order according to the first array, and a partial decompression function for obtaining a value obtained by accumulating difference information dependent on the first array;
The second data group is arranged such that each of the compressed data sets and a value obtained by accumulating the difference information corresponding to each of the compressed data sets are alternately arranged in the order according to the second array. A printing device including a transfer function to generate.

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