JP2000165679A - Picture processing method and picture transfer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of picture processing by compressing picture information by using pixel data as it is when matching with pixel data arranged to be away by extracted two-dimensional offset is not detected. SOLUTION: Picture data to be displayed on a display means is converted into a pixel data form and the arranging area of existent pixel data most continuously matched with specific pixel data is detected to extract an offset quantity. The cumulative table of the number of the most continuous by matched pixels is prepared for every offset quantity, and the offset quantity of a high order where the number of matched pixels is large is extracted to set to the offset quantities for compressing processing. When the matching of pixel data is detected by one of the offset quantities for compressing processing, the offset data is outputted to shift a compression pointer by the portion of the matching length. When the matching is not detected, pixel data instructed by the compressing pointer is outputted as it is to shift the compression pointer by the portion of one data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and an image transfer system, and more particularly to an image processing method suitable for a portable terminal having a small display panel and a relatively small storage capacity of an image memory. The present invention relates to a processing method and an image transfer system.

[0002]

2. Description of the Related Art In recent years, with the progress of semiconductor technology and liquid crystal technology, and integration with communication technology, notebook personal computers and PDs have been developed.
A portable information terminal such as A or a small communication device such as a mobile phone or a pager has been transmitting and receiving various information including images. In particular, PD
As for pagers such as A and pagers (hereinafter, these are collectively referred to as mobile terminals), those that maintain high functionality while being downsized to business card or wristwatch sizes have been developed. Such a small mobile terminal usually includes a small liquid crystal panel of about several inches and an image memory for storing image data corresponding to the display screen, and generally stores information such as characters and line drawings. Has the function of receiving and displaying a black-and-white binary image or a multi-valued image to which an intermediate gradation is added.

On the other hand, note-type personal computers and the like in recent years have an image processing function corresponding to a multi-tone color image, similar to a desktop personal computer and the like. Since a color image has a very large data amount compared to character information and the like, if it is stored in a storage medium as it is, a huge storage capacity is required. It takes a long time to do so. Therefore, a compression storage technique is indispensable for processing image information. JPEG will be briefly described as a typical example of the conventional image compression technique.

[0004] JPEG (Joint Photographic Expert Gr)
oup) is a still image compression method jointly compiled by the International Organization for Standardization (ISO) and the International Telegraph and Telephone Consultative Organization (CCITT). After the image data to be compressed is divided into blocks of 8 × 8 bit pixels, DCT (Discrete Cosin
e Transform: Discrete cosine transform) operation to rearrange the data into frequency components, convert each block from two-dimensional to one-dimensional data by zigzag scan or alternate scan, and calculate the DCT count of the block based on the quantization table. The data is converted into quantum data and subjected to variable length coding (lossless compression) processing with reference to a Huffman table. Conventionally, as image information compression and storage technologies, in addition to JPEG described above, BPEG, FAX
Various formats and standards such as (G1, G2, G3), MAG, GIF, Langless compression, LHA, and ZIP are used.

[0005]

The image compression technique as described above is intended for compression storage of image information originally having a large data amount and multi-gradation color images. A compression technique (image processing method) that can be favorably applied to a mobile terminal having a small capacity has not been developed. Further, in recent years, there has been an increasing demand for improvement in operability of a mobile terminal and visibility of a display screen, and various improvements for higher functionality have been demanded. for that reason,
When a general image processing method is applied to improve the efficiency and function of the image processing in the mobile terminal, the header data of the received image data alone is larger than the original data amount, and the amount of data in the image memory is increased. In addition to pressing down on the storage capacity, the time required for data transfer (transmission / reception) and image display processing becomes longer, and efficient image processing cannot be realized.
Had the problem that Therefore, an object of the present invention is to provide a good image processing method and an image transfer system applicable to transfer and display processing of image information in a mobile terminal having a small display panel such as a pager or a small capacity image memory. And

[0006]

According to a first aspect of the present invention, there is provided an image processing method comprising the steps of: blocking image information to be displayed on a display unit in a predetermined pixel unit and converting it into pixel data; Processing for sequentially detecting an arrangement area in which specific pixel data most continuously matches the data; calculating a two-dimensional offset between the detected arrangement area and the specific pixel data; A process of extracting a predetermined number of two-dimensional offsets in descending order of appearance frequency, sequentially specifying the pixel data, and determining whether or not the pixel data is located between the extracted two-dimensional offset separations. If the match is detected, the pixel data is replaced with the match length of the pixel data, and if the match is not detected, It uses the pixel data as it is characterized in that it comprises a and a process for compressing the image information.

According to a second aspect of the present invention, in the image processing method of the first aspect, the compressed image information is sequentially read, and it is determined whether or not the compressed image information belongs to the two-dimensional offset. If the pixel data belongs to a two-dimensional offset, the pixel data separated by the two-dimensional offset separation is copied based on the coincidence length of the replaced pixel data. The method includes a process of decompressing the image information using the information as it is, and a process of converting the pixel data included in the decompressed image information into a data format of the display unit. Furthermore, in the image processing method according to claim 3, in the image processing method according to claim 1 or 2, the two-dimensional offset used for the compression processing and the decompression processing of the image information is two-dimensional offset between the pixel data. Among the offsets, there are four two-dimensional offsets having a high appearance frequency. The image transfer system according to claim 4 executes the image processing method according to claim 1 or 2, compresses desired image information, and transmits the compressed image information via a communication unit; and the transmission unit. And receiving means for receiving the image information sent from the device, executing the image processing method according to claim 2 or 3, decompressing the image information, and outputting the image information to a display means. And

[0008]

Embodiments of the present invention will be described below with reference to the drawings. A. First, the compression processing in the image processing method according to the present invention will be described with reference to the drawings. FIG. 1 is a flowchart illustrating a procedure of a compression process of image information. First, image data (for example, dot data) to be displayed on predetermined display means such as a liquid crystal panel is converted into a pixel data format corresponding to a compression operation described later (S101). Next, an arrangement area (hereinafter, referred to as a pixel area) of the already-existing pixel data that most closely matches the specific pixel data is detected, and the offset amount is extracted (S10).
2). The extraction of the offset amount is executed for all the converted pixel data (S103). And
For each of the extracted offset amounts, a total table of the number of pixels that match most continuously is created (S104), and a higher-order offset amount with a larger number of matching pixels is extracted from the total table, and an offset amount for compression processing is extracted. Set to.

Then, the pixel data of the image-converted image data is scanned by sequentially shifting the compression pointer, and when a match of the pixel data is detected by any of the compression processing offset amounts (S105, S10).
6) Output the offset data, that is, the offset number and the coincidence length of the pixel data (S107),
The compression pointer is shifted by the matching length (S108),
On the other hand, if no pixel data match is detected,
The pixel data specified by the compression pointer, that is, the immediate symbol and the pixel data are output as they are (S
109), the compression pointer is shifted by one data (S
110). By executing the processing from S105 to S110 for all pixel data, (S1
11) The pixel-converted image data is compressed. Note that the compression processing is completed by associating the extracted offset data with the image data compressed by the series of processing.

As described above, the compression process is roughly divided into three steps: pixel conversion, offset amount setting, and compression operation. Hereinafter, each of these steps will be specifically described with reference to the drawings. (1) Pixel Conversion FIG. 2 is a conceptual diagram showing a process of converting image data from a dot data format to a pixel data format. here,
The image data to be compressed is, as shown in FIG. 2A, digital information corresponding to a small liquid crystal panel or the like, that is, a monochrome binary image (line drawing) in which pixel (dot) data is arranged in a matrix. Description Normal,
Image data displayed on a liquid crystal panel or the like is represented by one bit per pixel in the case of a black-and-white binary image, and in a vertical or horizontal direction as shown in FIG. It has a data structure that bundles several bits. In addition,
FIG. 2B shows an example in which 1 × 8 pixels are grouped. Therefore, as for each pixel corresponding to the liquid crystal panel, the original data in which 1 × 8 pixels are grouped into one group D1 is used as shown in FIG.
As a block D2, as described later, the data is converted into a pixel data array including m × n pixels.

By such pixel conversion, image data displayed on the liquid crystal panel is converted into a data format suitable for a compression operation to be described later.
It has a data structure that is different from the data structure in general compression processing in which pixel data is converted into (2 × 2 pixels). Also, in such pixel conversion,
Conventionally, image data is handled in units of dots, and predetermined dots are divided into blocks to be handled as pixel data. Therefore, the data size after conversion is the same as the data size before conversion. Therefore, the same internal area secured in the image memory can be used.
As will be described later, the capacity of the image memory used for pixel conversion is the same in the decompression processing of image data, so that even if the decompression processing side is a mobile terminal such as a pager, the mounted image The storage capacity of the memory can be used effectively.

(2) Offset Setting FIG. 3 is a conceptual diagram showing the coincidence detection processing of pixel data, and FIG. 4 is a cumulative table of two-dimensional offset values created by the coincidence detection processing. As shown in FIG. 3, in the pixel data coincidence detection processing, the specific pixel data (hereinafter, referred to as a target pixel) Px is most continuous with any of the other pixel regions P11, P12, P13,. Is determined by comparing all of the pixel data. At this time, the detection process shifts the existing pixel region to be compared by one pixel at a time, and calculates the two-dimensional offset of the deviation of the X-Y coordinate value from the position of the pixel region that matches the longest with the target pixel Px. It is extracted and counted as values (ΔX, ΔY).

More specifically, as shown in FIG. 3, a target pixel Px serving as a comparison reference is shifted from the pixel area P11 at the upper left corner of the screen composed of m × n pixels one pixel at a time in the right direction of the screen. And compare the data. When the pixel data group for one line (line) is processed and reaches the right end of the screen, the process returns to the left end of the screen,
Similarly, the comparison process is sequentially performed on the line one pixel below the pixel data group that has been subjected to the comparison process. For example, when the data of the existing pixel area P13 coincides with the target pixel Px, the coincident pixel P13 and the target pixel Px are simultaneously shifted rightward, and the next target pixel Py and the pixel area P14 are further shifted. And performs a comparison process. Such comparison processing (P13-Px, P14-Py, P1
5-Pz,...) Are repeated to count the shift amount at which the pixel data matches each other, that is, the number of matching pixels (long).

Then, the offset values are listed (stored) in a cumulative table as shown in FIG. In this process, the image data is mx
In the case of n pixels, scanning is sequentially performed for each pixel, and the scanning is performed for m × n pixels as a whole. In this way, the coincidence is sequentially compared between the target pixel and each pixel area while changing the two-dimensional offset, and as shown in FIG.
A cumulative table of the number of longest matching pixels is obtained for each dimension offset. Next, based on the created total table, an arbitrary number (for example, 4
), And set the offset numbers to “0”, “1”,
“2” and “3” are set, and the offset data is registered as a two-dimensional offset for compression processing in a compression reference table (not shown).

(3) Compression Operation FIG. 5 is a conceptual diagram showing a fixed two-dimensional offset applied to the compression operation and the compression operation. As described above, the two-dimensional offsets (also referred to as fixed two-dimensional offsets) used in the compression processing are set in the cumulative table shown in FIG. That is, as shown in FIG. 5A, the two-dimensional offset of the adopted offset numbers “0” to “3” has a deviation (ΔX, ΔY) of the XY coordinate value with respect to the target pixel Px, (-2, -2), (+
(-1, -1), (± 0, -1), and (-1, ± 0). Then, in the compression processing of the image data, as shown in FIG. 5B, the target pixel Px is set as a compression target and is compared with data of a pixel area separated by a fixed two-dimensional offset. If the match of the pixel data is detected using any of the fixed two-dimensional offsets, the number of pixels (long) that continuously match the number of the two-dimensional offset.
Is output and replaced with the data of the target pixel Px. On the other hand, if no coincidence of pixel data is detected using any of the fixed two-dimensional offsets, the immediate symbol (mark) of the target pixel and the pixel data are output as they are.

More specifically, for the pixel-converted image data, the compression pointer is started from the pixel area P11 at the upper left corner, and proceeds to the lower row each time one row ends, and the pixel area Pend at the lower right corner. Scan sequentially until At this time, while sequentially setting each pixel area as the target pixel Px and scanning, the existing two-dimensional offsets set at the fixed two-dimensional offset are arranged at positions separated by any one of the four types of two-dimensional offsets. Is determined whether or not the pixel region of the target pixel Px matches the data of the target pixel Px. Here, when it is determined that the target pixel Px and the subsequent pixel data group have the same arrangement as the already-existing pixel data group, the two-dimensional offset number referred to in the determination is the same as that of the target pixel Px. A compression process is performed to replace the target pixel Px and a subsequent pixel data group according to the determined number of pixels. On the other hand, if the data of the target pixel Px does not match the data of the existing pixel area even when referring to any two-dimensional offset, the data of the target pixel Px is output as it is because replacement with the existing pixel data is not possible. Thus, no substantial compression processing is performed.

With respect to the target pixel replaced by the coincidence of the pixel data and the subsequent pixel data group, a pixel area shifted by the coincidence length is designated as the next target pixel, while the pixel data does not coincide. For the target pixel, the next (adjacent) pixel area is specified, and the above series of processing is repeatedly executed until the lower right pixel area Pend is specified. The image data (compressed data) after the compression processing is stored in a predetermined memory area after adding offset data set to a fixed two-dimensional offset, as described later.

The immediate symbol and the pixel data output when the pixel data do not match, and the two-dimensional offset number and the matching pixel length output when the pixel data match, are converted into fixed Huffman codes, respectively. It is preferable to output the data from the pixel data, and by performing such processing, it is possible to suppress a statistical variation in the matching frequency of the pixel data. In particular, the code corresponding to the two-dimensional offset number is preferably determined in consideration of the frequency of appearance, and for example, it is preferable to set a code having a high frequency of appearance to be higher (lower number). According to such an image compression method, the two-dimensional offset is made variable, the number of the two-dimensional offsets is reduced, and the simple data comparison process and the replacement process using the reference offset data are executed. Can be compressed.

Next, a compression format of image data compressed by the above-described image compression method will be described with reference to the drawings. FIG. 6 is a conceptual diagram showing a structure of a file header portion of compressed image data, FIG. 7 is a conceptual diagram showing a structure of two-dimensional offset data, and FIG. 8 is a conceptual diagram showing a structure of a compressed data portion. . As shown in FIG. 6, the file header section is configured by the first 10 bytes of the file. Specifically, the header mark symbol (+00) and the number of pixels (+0)
1), X display start position (+02), Y display start position (+
03), X total dot count (+04), Y total dot count (+0)
5) Two-dimensional offset data "0" (+06),
“1” (+07), “2” (+08), “3” (+0
9), and these 10-byte file headers are associated with each compressed data (+ 0A-).

The two-dimensional offset data shown in FIG. 6 is composed of 8-bit information as shown in FIG. 7A, and Y is represented by upper 4 bits as shown in FIG. 7B. The two-dimensional offset shown in FIGS. 4 and 5 is defined by indicating the coordinate value deviation (ΔY) in the direction and the coordinate value deviation (ΔX) in the X direction by the lower 4 bits. In the two-dimensional offset data, as described above, only one of the two-dimensional offset numbers “0” to “3” is referred to in the compression processing, and thus no coincidence of pixel data is detected. In this case, for example, information (0x0) indicating that the data is uncompressed data is stored in the two-dimensional offset data “0” of the seventh byte (+06: XY0).
0), the subsequent 8th byte (+0
The non-compressed image data (pixel data itself) is stored in this memory area with the offset data of the 10th byte (+09: XY3) from 7: XY1) and the compressed data (+ 0A-) not set.

The compressed data section shown in FIG. 6 stores image data compressed rightward from the upper left end of the screen, right-justified by a bit string. And
The compression code set at this time is, as shown in FIG.
The function is set by the fixed Huffman code. Specifically, the compression code uses a 4-bit bit string to specify the type of data compression and non-compression and the referenced two-dimensional offset data. For example, the compression code “0” indicates non-compression, and the pixel data itself is set in the compression data portion. On the other hand, when the compression code is “10”,
The same data as the two-dimensional offset data “0” (XY0) is set, and the number of matching pixels is defined as a numerical code (n) by a Huffman code as shown in FIG. In the case of the compression code “110”, the same data as the two-dimensional offset data “1” (XY1) is used. In the case of the compression code “1110”, the same data as the two-dimensional offset data “2” (XY2) is used. If the data is a compressed code “1111”, the same data as the two-dimensional offset data “3” (XY3) is set together with the numerical code. FIG. 9 is a Huffman code table that associates the number of matching pixels with a numerical code.

Next, a method of setting the number of two-dimensional offsets (fixed two-dimensional offsets) to be referenced in the above-described image compression method will be described with reference to the drawings. FIG.
0 is an experimental result showing the relationship between the number of fixed two-dimensional offsets for various image data and the compression ratio. FIG.
As shown in the figure, when the number of fixed two-dimensional offsets is 3 or less, the compression ratio is high and the dispersion tends to be large.
When the number of fixed two-dimensional offsets is 4 or more, the compression ratio is 10
And a tendency to stabilize and stabilize the variation. Therefore, based on such an experimental result, by setting the number of two-dimensional offsets referred to in the compression processing to approximately four or four or more, efficient compression processing can be realized.

As described above, the image data is converted from dots to pixels, the coincidence state between the target pixel and other pixels and the two-dimensional offset are detected based on the pixels, and a cumulative total table is created. By setting a plurality of (for example, four types) two-dimensional offsets having high values as reference offsets in the compression operation, the compression process is executed by referring to any of the set two-dimensional offsets and replacing the target pixel with offset data. can do. Therefore, the two-dimensional offset can be set variably, the number of the two-dimensional offsets can be appropriately suppressed, and the image data can be efficiently compressed. Therefore, the pager having a small display panel and a relatively small storage capacity of the image memory can be used. A good image processing method can be provided by applying the present invention to image data displayed on a mobile terminal.

B. Decompression processing Next, the decompression processing in the image processing method according to the present invention will be described with reference to the drawings. Here, the decompression process
Similar to a general image processing method, a process opposite to the compression algorithm is performed. FIG. 11 is a flowchart showing the procedure of the image information decompression process. First, based on information set in a file header section of compressed image data, parameters such as a two-dimensional offset value and a size of image data used in a decompression operation described later are calculated (S201). Next, the compressed data is sequentially read from the head (S202), and it is detected whether or not an offset number is included in the header portion of the data (S2).
03), It is determined whether the read data is data belonging to the two-dimensional offset. If the offset number is included in the header portion, the number of matching pixels (length) following the offset number is read (S204), and the pixel data is located at a position separated by the two-dimensional offset corresponding to the previously read offset number. Is copied (S20
5). On the other hand, if the offset number is not included in the header part, the data (pixel data) following the header part is read out because it is uncompressed data and pixel data itself (S206), and is set as decompressed data (S206). S207). By executing the processing from S202 to S207 for all the compressed data (S208), decompressed data in which pixel data is arranged is obtained. Then, the pixel data format of the decompressed data is converted into the data format (dot data) of the display panel for reproducing and displaying the restored image (S209).

As described above, the decompression process is roughly composed of three steps: parameter setting, decompression operation, and dot conversion. Below, for each of these steps,
This will be specifically described with reference to the drawings. (4) Parameter Setting FIG. 12 is a conceptual diagram showing parameters used when decompressing compressed data. Here, the image data to be decompressed is compressed data having a file header structure as shown in FIG. FIGS. 12A and 12B
As shown in (1), a memory area necessary for storing image data obtained by decompressing the compressed data is secured, and a two-dimensional offset referred to in the decompression operation is vector-calculated. Specifically, based on the information set in the file header section of the compressed image data, as shown in FIG. 12A, in order to store the decompressed image data in association with each pixel area, , M × n
A memory area for pixels is secured in the image memory. Further, as shown in FIG. 12B, a two-dimensional offset corresponding to the two-dimensional offset (fixed two-dimensional offset) for the compression processing shown in FIG. 5 is vector-calculated.

(5) Decompression Operation FIG. 13 is a conceptual diagram showing a decompression operation when an offset number is detected, and FIG. 14 is a conceptual diagram showing a decompression operation when an offset number is not detected. . Here, the decompression operation decompresses the compressed data by the reverse procedure of the above-described compression processing. Data is sequentially read from the head of the compressed data, and as shown in FIG. 13A, when any of offset numbers “0” to “3” is included in the file header portion of the read data, the data is fixed. Because it is compressed data that has been compressed by a two-dimensional offset,
Read the matching pixel length following the offset number. Then, the pixel data which is arranged at a position separated by the two-dimensional offset corresponding to the offset number and already decompressed is copied.

More specifically, as shown in FIGS. 13A and 13B, for example, the offset number read from the file header portion of the compressed data is “0”, and the subsequent matching pixel length Is “5”, the data for the five pixels from the pixel area PX1 to be decompressed and the subsequent pixel areas PX2 to PX5 is
Offset number “0” based on pixel area PX1
(ΔX = −2, ΔY = −)
Since the data has the same configuration as the data in the pixel regions PN1 to PN5 separated by 2), the compressed data is decompressed by copying these existing pixel data.
Next, the next pixel area PX6 shifted by the matching pixel length is designated as a decompression target, the next data in the file header portion is read, and the decompression operation is continued. On the other hand, as shown in FIG. 14A, when the data read from the file header portion does not include the offset number, it is determined that the data is uncompressed data, and the pixel data is read as it is. Set data in the pixel area to be decompressed.

More specifically, as shown in FIGS. 14A and 14B, the uncompressed pixel data following the immediate area mark information read from the file header portion is decompressed. The output is directly set to PX1. Next, for the next pixel area PX2 adjacent to the decompression target, the next data in the file header portion is read, and the decompression operation is continued. The decompression operation of the compressed data is completed by executing such a series of processing until there is no more compressed data, or by executing all the pixel regions set in the image memory. Here, in the case of the most normal data, the decompressed data is set in all of the pixel areas set in the image memory when the compressed data is exhausted.

(6) Dot Conversion FIG. 15 is a conceptual diagram showing a process of converting the decompressed data set by the decompression operation from the pixel data format to the dot data format. Here, a description will be given assuming that the display panel for reproducing and displaying the restored image corresponds to the data format of a black-and-white binary image (line drawing) in which dot data is arranged in a matrix. In the conversion of the data format, pixel data is converted into dot data by the reverse procedure of the above-described pixel conversion. More specifically, as shown in FIG. 15A, the pixel data set in each pixel area of the image memory by the decompression operation is replaced with dot data D11 composed of 2 × 2 pixels, and the entire decompression data is converted into dot data. Convert to array image data. As described above, image data displayed on a liquid crystal panel or the like usually has a data structure in which several bits are bundled in the vertical or horizontal direction.
As shown in (b), a dot configuration (for example, 1 × 8 pixels) D12 corresponding to the specification of a display device such as a liquid crystal panel is used.
And by optimizing the display data,
As shown in FIG. 15C, the restored image is displayed on a display panel such as a pager.

As described above, whether or not the compressed data belongs to the two-dimensional offset is determined based on the data sequentially read from the header part of the compressed data. Based on the offset number and the matching pixel length, the already-existing pixel data is copied. If the data does not belong to the two-dimensional offset, the data is determined as uncompressed data, and the read data is set as it is. Decompression processing can be performed favorably while suppressing the data amount of the header portion. Therefore, even if the device that receives the compressed data and reproduces and displays the restored image is a mobile terminal such as a pager having a small display panel and a small-capacity image memory, the storage capacity of the memory can be quickly reduced. An image processing method capable of performing decompression and display output can be provided.

In the above-described embodiment, an example has been described in which 2 × 2 dots of image data displayed on the display panel are treated as one pixel, and compression and decompression are performed. It goes without saying that the present invention can be applied favorably even when one dot is one pixel, or when m ′ × n ′ dots are set as one pixel. Further, an example has been described in which image data having a black-and-white binary image is subjected to image processing, but it is needless to say that multi-valued image (multi-gradation display) data may be used. That is, as shown in FIG. 16, when the pixel configuration is 2 × 2 pixels (dots) as one pixel, the pixel configuration corresponds to a binary black-and-white image as described above. Or, when 2 × 1 pixel is one pixel, a quaternary image having a quaternary gradation level, and when 1 × 1 pixel is one pixel, a 16-valued gradation level , And these image information can be satisfactorily compressed and decompressed on a pixel-by-pixel basis. FIG. 16 is a correspondence table showing dot-pixel correlations and types of image data.

Next, an image transfer system to which the image processing method according to the present invention is applied will be described with reference to the drawings. FIG. 17 is a diagram showing a schematic configuration of an image transfer system when a pager such as a pager is used as a mobile terminal. As shown in FIG. 17, the image transfer system includes:
A network 10 such as a telephone line to which communication devices such as a telephone 21 and a personal computer 22 are connected, and a pager connected to one end of the network 10 for transferring predetermined image information (messages and line drawing data) to a designated pager 30. The image processing apparatus includes a center 20 and a pager 30 that receives image information transmitted from the pager center 20 and displays the image information on a display unit such as a liquid crystal panel. Here, the communication devices such as the telephone 21 and the personal computer 22 connected to the network 10 and the pager center 20 are not limited to those constructed by wire, but are also provided via mobile terminals such as mobile phones and PHSs and satellite communication facilities. It goes without saying that a network may be constructed by wireless.

In the image transfer system having such a configuration, the pager center 20 is operated by the telephone 21 or the personal computer 22 or the like.
, Or by designating the address of the pager 30 directly from the pager center 20 to encode and transmit desired image information. That is, by executing the above-described image information compression processing, the two-dimensional offset of a small-capacity black-and-white binary image or a multi-valued image including an intermediate gradation is variably set, and the number thereof is appropriately suppressed. And can be efficiently compressed. The addressing of the pager 30 may be an information service address in addition to a personal address.

On the other hand, the addressed pager 30
Receives image information transmitted from the pager center 20, decodes the image information, and outputs the information to a liquid crystal panel, thereby transmitting predetermined information to the pager owner. That is, by performing the above-described decompression processing of image information, the decompression processing can be performed favorably while suppressing the data amount of the header portion associated with the compressed data. Even in the pager 30 having a small image memory, the transferred image information can be quickly displayed and output without squeezing the storage capacity of the memory.

Next, a schematic configuration of a pager applied to the above-described image transfer system will be described with reference to the drawings. FIG. 18 is a block diagram showing a schematic configuration of a pager applied to the image transfer system according to the present invention. As shown in FIG. 18, the pager 30 includes an RF unit 31, a decoder unit 32, an ID-ROM 33, a control unit 34,
It has a display unit 35, an operation unit 36, and an image memory 37. The RF unit 31 allows the message sender to receive a carrier wave such as address information and image information transmitted from an information device such as a telephone or a personal computer via a pager center or directly from the pager center, and set the frequency to an intermediate frequency. The data is converted and transmitted to the subsequent decoder unit 32. The decoder section 32 reads out the self-address stored in the ID-ROM 33 or the address for the information service, extracts the image information addressed to itself from the information transmitted from the pager center, and outputs the signal The information is transmitted to the control unit 34 having a control function.

The display section 35 displays commands input via an operation section 36 having key switches and the like, and messages and image information stored in an image memory 37 described later. As the display unit 35 applied to the pager 30, a STN type monochrome liquid crystal panel excellent in display characteristics and power consumption characteristics is generally used. However, the display unit 35 is not limited to the monochrome liquid crystal panel, and is not limited to a monochrome liquid crystal panel. In addition to the corresponding liquid crystal panel, the liquid crystal panel may correspond to a multi-value image or a color image having an intermediate gradation. The control unit 34 stores the image information extracted by the decoder unit 32 in an internal area secured in the image memory 37, performs predetermined image processing, converts the image information into a data format corresponding to the specification of the display unit 35, and restores the data. Play and display the image. That is, a header portion is extracted from the image information stored in the image memory 37, and data compression or non-compression is detected based on the presence or absence of an offset number. In the case of compressed data, based on the offset number and the matching pixel, Image data was decompressed by copying and setting the previously-existing pixel data, and in the case of uncompressed data, setting the read data as it was as pixel data to decompress image information and convert it to a data format corresponding to the LCD panel specifications Thereafter, a process of displaying the restored image on the display unit 35 is performed.

Therefore, in the image transfer system according to the present embodiment, since the image information transmitted from the pager center is the compressed data which has been subjected to the predetermined compression processing, the above-described image information decompression processing is executed. By incorporating the program to be executed into the ROM or the like in the control unit 64,
Control processing, such as decompression processing of the received image information, display processing on the display unit, and command control from the operation unit, is not excessively performed on the image processing function of the control unit 34 without squeezing the storage capacity of the image memory 37. It is possible to contribute to the construction of an image transfer system that can be executed well without imposing a load on the system. In the above-described embodiment, a pager such as a pager is shown as an example. However, the present invention can be suitably applied to a mobile terminal having a small screen such as a mobile phone, a PHS, or a PDA, which has recently become popular. Needless to say.

[0038]

According to the first aspect of the present invention, the process of converting image information to be displayed on the display means into pixel data by blocking in a predetermined pixel unit and the specific pixel data most continuously coincide with each other. A process of sequentially detecting the arrangement area of the previously-existing pixel data, a process of extracting a predetermined number of two-dimensional offsets in descending order of appearance frequency among the two-dimensional offsets between the detected pixel data, and a process of extracting the extracted two-dimensional offsets If the pixel data detected based on the offset matches, the compression process is performed to replace the pixel data with the matching length of the pixel data, so that the two-dimensional offset is variably set, and the number of the two-dimensional offset is appropriately suppressed to suppress the image. Since information can be compressed and header information can be reduced in size, a small display panel and image memory are installed. Transfer of the image information in a mobile terminal such as a PDA or pager, can be favorably applied to the display processing. That is, the image processing method according to the present invention uses a sliding dictionary method, a small number of two-dimensional offsets, and a fixed Huffman code to produce a small-capacity black-and-white binary image or a multi-valued image including an intermediate gradation. Can be provided a new image processing method capable of efficiently compressing the image.

According to the second aspect of the present invention, in the image processing method of the first aspect, a process of sequentially reading the compressed image information and determining whether or not the image information belongs to a two-dimensional offset, If the image data belongs to the dimensional offset, decompression processing for copying the pixel data (corresponding to the matching length) arranged at a position separated by the two-dimensional offset, and a data format corresponding to the display panel for the pixel data of the decompressed image information By performing the conversion process, the decompression process can be performed efficiently while suppressing the data amount of the header information added to the compressed image information. A good image processing method can be provided by applying to transfer and display processing in a mobile terminal such as a mounted PDA or pager.

According to a third aspect of the present invention, in the image processing method according to the first or second aspect, as the two-dimensional offset, the four most frequently occurring two-dimensional offsets between pixel data are used. By adopting the two-dimensional offset, the two-dimensional offset can be variably set, and the compression ratio can be increased while appropriately suppressing the number of the two-dimensional offset.
The decompression process can be performed efficiently, and the data amount of the header information of the compressed image information can be significantly reduced. According to a fourth aspect of the present invention, the image processing apparatus according to the first or second aspect executes a compression process of the image information to compress desired image information, and transmits the compressed image information via a communication unit. And receiving the received image information.
Receiving means for decompressing and displaying the described image information, decompressing the image information, and displaying the image information on the display means, thereby efficiently compressing a binary or multi-valued image for a small screen. , Transfer, decompression, and display, and perform image processing corresponding to the capabilities of the display panel, image memory, and processor of the receiving means. The visibility of the display screen can be improved.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a procedure of image information compression processing.

FIG. 2 is a conceptual diagram illustrating a process of converting image data from a dot data format to a pixel data format.

FIG. 3 is a conceptual diagram showing a coincidence detection process of pixel data.

FIG. 4 is a cumulative table of two-dimensional offset values created by a match detection process.

FIG. 5 is a conceptual diagram showing a fixed two-dimensional offset applied to a compression operation and a compression operation.

FIG. 6 is a conceptual diagram showing the structure of a file header section of compressed image data.

FIG. 7 is a conceptual diagram showing a structure of two-dimensional offset data.

FIG. 8 is a conceptual diagram showing a structure of a compressed data section.

FIG. 9 is a Huffman code table that associates the number of matching pixels with a numerical code.

FIG. 10 is an experimental result showing the relationship between the number of fixed two-dimensional offsets and the compression ratio for various image data.

FIG. 11 is a flowchart illustrating a procedure of image information decompression processing.

FIG. 12 is a conceptual diagram showing parameters used when decompressing compressed data.

FIG. 13 is a conceptual diagram showing a decompression operation when an offset number is detected.

FIG. 14 is a conceptual diagram illustrating a decompression operation when an offset number is not detected.

FIG. 15 is a conceptual diagram illustrating a process of converting decompressed data set by a decompression operation from a pixel data format to a dot data format.

FIG. 16 is a correspondence table showing dot-pixel correlations and corresponding images.

FIG. 17 is a diagram illustrating a schematic configuration of an image transfer system when a pager is used.

FIG. 18 is a block diagram illustrating a schematic configuration of a pager.

[Explanation of symbols]

 Reference Signs List 10 network 20 pager center 21 telephone 22 personal computer 30 pager 31 RF unit 32 decoder unit 33 ID-ROM 34 control unit 35 display unit 36 operation unit 37 image memory

Claims (4)

[Claims] 1. A process of blocking image information to be displayed on a display unit in a predetermined pixel unit and converting the block into pixel data, wherein a specific pixel data is most continuous with respect to all the converted pixel data. A process of sequentially detecting coincident arrangement regions; calculating a two-dimensional offset between the detected arrangement region and the specific pixel data; and, among the two-dimensional offsets, a predetermined number of two-dimensional offsets in descending order of appearance frequency And a process for sequentially specifying the pixel data, detecting a match with the pixel data arranged between the extracted two-dimensional offset separations, and detecting the match if the match is detected. If the match is not detected, the pixel data is used as it is and the image data is replaced with the match length of the pixel data. An image processing method, comprising: a process of compressing information. 2. The compressed image information is sequentially read, and it is determined whether or not the compressed image information belongs to the two-dimensional offset. If the compressed image information belongs to the two-dimensional offset, the compressed image information is determined based on the coincidence length of the replaced pixel data. Copying the pixel data separated by the two-dimensional offset, and, if the pixel data does not belong to the two-dimensional offset, decompressing the image information using the image information as it is; 2. The image processing method according to claim 1, further comprising: converting the pixel data included in the information into a data format of the display unit. 3. The two-dimensional offset used in the compression processing and decompression processing of the image information is four two-dimensional offsets having a high appearance frequency among the two-dimensional offsets of the pixel data. The image processing method according to claim 1 or 2, wherein 4. A transmitting means for executing the image processing method according to claim 1 to compress desired image information and transmitting the compressed image information via a communication means, and said image information transmitted from said transmitting means. And performing the image processing method according to claim 2 or 3,
A receiving unit that decompresses the image information and outputs the image information to a display unit.