JP4757162B2 - Image encoding device, image decoding device, mobile phone, image encoding method, image decoding method, image encoding program, and image decoding program - Google Patents

Description

  The present invention relates to an image encoding device, an image decoding device, a mobile phone, an image encoding method, an image decoding method, an image encoding program, and an image decoding program, and in particular, an image encoding device capable of decoding with a small amount of calculation. The present invention relates to an image decoding apparatus, a mobile phone, an image encoding method, an image decoding method, an image encoding program, and an image decoding program.

  In recent years, screen resolution has been improved in various devices including portable devices, and high-level character display quality has been demanded. Therefore, if it is a conventional bitmap font (hereinafter abbreviated as “font”), it is necessary to increase the number of dots constituting the character.

  Furthermore, with the widespread use of the above devices, the types of characters handled by the devices have increased, and the amount of character image data processed by the devices has increased.

  For this reason, the necessity of the encoding method which can compress the data amount of a character image efficiently is increasing.

  In recent years, as a standard for encoding binary images, a method with high encoding efficiency incorporating arithmetic encoding has been devised, such as a method proposed by JBIG (Joint Bi-level Image experts Group) (IS11544). ing.

Further, as a technique for simply encoding a binary image, there is a technique disclosed in Japanese Patent Laid-Open No. 63-155957 (hereinafter referred to as Patent Document 1). The technique disclosed in Patent Document 1 is a technique of encoding using the fact that adjacent lines are similar in a normal image, and a value of 0 is calculated by calculating an exclusive OR. This is a technique for increasing the coding efficiency while increasing the number of bits having, and maintaining reversibility.
JP-A 63-155957

  However, in the conventional encoding technique disclosed in Patent Document 1, it is assumed that the distribution of word values is a word or byte occupying characters (hereinafter, “byte” is a word consisting of 8 bits). The word “word” is used depending on the position of the character image data (font data) unless it is specifically limited. When such a technique is used as it is in order to encode a bitmap font as a normal binary image, there is a problem that the processing may not always be performed efficiently.

  In addition, although the above-mentioned JBIG method has been spread to some extent, there is a problem that it is difficult to use for encoding character image data that requires a large amount of calculation due to complicated processing and needs to be decoded by a small device. is there.

  The present invention has been made in view of such a problem, and is an image encoding device, an image encoding method, and an image encoding program capable of encoding image data having a predetermined characteristic with high efficiency. Another object of the present invention is to provide an image decoding apparatus, a mobile phone, an image decoding method, and an image decoding program capable of decoding encoded data with a small amount of calculation.

In order to achieve the above object, according to one aspect of the present invention, an image encoding device is an image encoding device for encoding character image data specified by character identification information included in image data. Reading means for reading out character image data for each character from the image data, and the character image data for one character in a processing unit size that is an integral number of a size in the first direction. An image dividing means for generating divided unit image data by dividing in a second direction orthogonal to the direction of 1, and the value of the nth line parallel to the first direction and nth included in the divided unit image data; The difference for each dot position between the value of the (n−1) th line adjacent to the line in the second direction is calculated by a predetermined method, and the difference is the value of the nth line for each line of n ≧ 1. and then, in the 0 line (n = 0 of the line) In its a processing division unit image data generating means for generating a processed divided unit image data is used as it is the value of the zeroth line division unit image data, processing the divided unit image data obtained from the character image data of one character minute Encoding means for continuously encoding a plurality of character image data and generating encoded data.

Preferably, the image encoding device includes an access table generating unit configured to generate an access table indicating correspondence between information specifying character image data for one character and a position corresponding to the character image data on the encoded data. Further prepare.

Good Mashiku is character identification information includes a character code or a character code and font identification information.

Preferably, the image encoding device further includes an acquisition unit that acquires correspondence between the character identification information and the glyph, and the access table generation unit acquires an internal character code from the character identification information of the character image data; Based on the acquired internal character code and the correspondence between the acquired character identification information and the glyph, a means for specifying the glyph corresponding to the acquired internal character code, the encoded data is searched, and the processing divided unit image data Means for generating a correspondence between the position of the character image data represented by the character identification information corresponding to the glyph on the encoded data by extracting the boundary position corresponding to each Means for specifying a position corresponding to the character image data on the encoded data by referring to the correspondence relationship from the glyph.

Preferably, the image encoding device includes a calculating unit that calculates a data amount after encoding of the first processed divided unit image data obtained from the first divided unit image data obtained from the character image data, and the character image. Rotation means for generating rotated image data by rotating the data by 90 degrees, and second divided unit image data obtained by dividing the rotated image data in the first direction, the nth included in the second divided unit image data A predicting unit that calculates a difference between the value of the line and the value of the (n−1) -th line, and predicts the encoded data amount of the second processed division unit image data using the difference as the value of the n-th line. The encoding means encodes the processed divided unit image data having the smaller data amount after the encoding among the first processed divided unit image data and the second processed divided unit image data.

  More preferably, the encoding means further includes means for generating information indicating which of the first processed division unit image data and the second processed division unit image data is encoded.

According to another aspect of the present invention, an image decoding device is an image decoding device for performing decoding processing on encoded data generated by the image encoding device to obtain character image data for one character. Te, an acquiring unit that acquires information specifying the character image data of one character, and information specifying the character image data, the access table showing the correspondence between the position corresponding to the character image data in the encoded data The specifying means for specifying the position on the encoded data corresponding to the information for specifying the character image data that is accessed and acquired, and the character encoding data is successively encoded by the image encoding device. in on the generated encoded data, it decodes the data in a specific location, and decoding means for generating a plurality of processing the divided unit image data, for each of the divided unit image data Using the value of the (n-1) th line and the value of the nth line of each processed division unit image data, the value of the nth line of each divided unit image data is calculated, and the plurality of processed divisions Character image data for one character by integrating a creation unit that generates division unit image data from unit image data, and a plurality of division unit image data created from the plurality of processed division unit image data by the creation unit. And an integration means for generating.

Preferably, the image decoding apparatus, if the character image data to access the information indicating whether or not that is rotated 90 degrees at the time of coding, in which the character image data is rotated 90 degrees at the time of encoding And a means for rotating the generated character image data by 90 degrees in the opposite direction to the rotation direction at the time of encoding.

According to still another aspect of the present invention, a mobile phone is equipped with the image decoding device.
According to still another aspect of the present invention, an image encoding method is a method of encoding character image data specified by character identification information included in image data in an image encoding device, the image encoding method comprising: A reading step for reading character image data for each character; and character image data for one character , each orthogonal to the first direction at a processing unit size that is an integral number of the size in the first direction . second dividing direction, an image dividing step of generating a divided unit image data, included in the divided unit image data, the value of the n-th line parallel to the first direction the second direction to the n-th line to The difference for each dot position between the value of the (n−1) th line adjacent to the line is calculated by a predetermined method, and for each line of n ≧ 1, the difference is set to the value of the nth line, and the 0th line ( for n = 0) A processed image creation step for generating processed divided unit image data using the value of the 0th line of the divided unit image data as it is, and processed divided unit image data obtained from character image data for each character, An encoding step for continuously encoding the image data and generating encoded data.

Preferably, the image encoding method, the first processing division unit image data obtained from the first division unit image data obtained from the character image data, a calculation step of calculating a data amount after coding, character image data A rotation step for generating rotated image data by rotating 90 degrees, and second divided unit image data obtained by dividing the rotated image data in the first direction, the nth line included in the second divided unit image data. Calculating a difference between the value and the value of the (n−1) -th line, and predicting the encoded data amount of the second processed division unit image data using the difference as the value of the n-th line. Further, in the encoding step, of the first processed division unit image data and the second processed division unit image data, the processed divided unit image data having a smaller data amount after encoding is encoded. That.

According to still another aspect of the present invention, an image decoding method performs a decoding process on encoded data generated by sequentially encoding a plurality of character image data by the above-described image encoding method. and, 1 a the characters of the character image data method, an acquisition step of acquiring information specifying the character image data of the one character, and information specifying the character image data, on the encoded data equivalent access the access table showing the correspondence between the position corresponding to the character image data, corresponding to the information specifying the character image data acquired, a specifying step of specifying a position on the encoded data, the above-described image coding of the generated encoded data by performing encoding processing in succession a plurality of character image data by a method, and decodes the data in a specific position, a plurality of processing division unit image Using the decoding step for generating data, the value of the (n-1) th line of each division unit image data, and the value of the nth line of each processed division unit image data, each division unit image data A n-th line value is calculated, and a creation step for generating division unit image data from each of the plurality of processing division unit image data, and a plurality of pieces created from the plurality of processing division unit image data in the creation step An integration step of integrating the division unit image data to generate a character image for one character .

Preferably, the image decoding method, when the character image data in which access information indicating whether or not that is rotated 90 degrees at the time of encoding, the character image data is rotated 90 degrees at the time of encoding, The method further includes the step of rotating the generated character image data by 90 degrees in the opposite direction to the rotation direction at the time of encoding.

According to still another aspect of the present invention, an image encoding program is a program for causing a computer to execute a process of encoding character image data specified by character identification information included in image data , the image data A reading step of reading character image data for each character from the character image data, and each character image data for one character in the first direction with a size of a processing unit that is an integral number of the size in the first direction . An image dividing step for dividing the image in the second direction orthogonal to generate divided unit image data; a value of the nth line parallel to the first direction and a second value included in the divided unit image data ; The difference for each dot position between the values of the (n−1) th line adjacent in the direction is calculated by a predetermined method, and for each line of n ≧ 1, the difference is the value of the nth line, and the 0th line (N = 0 A processed image generation step for generating processed divided unit image data using the value of the 0th line of the divided unit image data as it is, and processed divided unit image data obtained from character image data for each character. Are sequentially encoded for a plurality of character image data , and an encoding step for generating encoded data is executed.

Preferably, the image coding program, the first processing division unit image data obtained from the first division unit image data obtained from the character image data, a calculation step of calculating a data amount after coding, character image data A rotation step for generating rotated image data by rotating 90 degrees, and second divided unit image data obtained by dividing the rotated image data in the first direction, the nth line included in the second divided unit image data. Calculating a difference between the value and the value of the (n−1) -th line, and predicting the encoded data amount of the second processed division unit image data using the difference as the value of the n-th line. Further, in the encoding step, the processed divided unit image data having the smaller encoded data amount out of the first processed divided unit image data and the second processed divided unit image data. The encoding.

According to still another aspect of the present invention, an image decoding program executes encoded image data generated by sequentially encoding a plurality of character image data by executing the above-described image encoding program . A program for causing a computer to execute a decoding process to obtain character image data for one character , an acquisition step for acquiring information for specifying character image data for one character, and specifying character image data and information, accessing the access table showing the correspondence between the position corresponding to the character image data in the encoded data, corresponding to the information specifying the character image data acquired, identifying the location on the encoded data It is generated by encoding a plurality of character image data continuously by executing the specific step and the above-described image encoding program. On encoded data, decodes the data in a specific position, a decoding step of generating a plurality of processing the divided unit image data, the (n-1) of each of the divided unit image data line values And the value of the nth line of each of the processed divided unit image data, the value of the nth line of each divided unit image data is calculated, and each divided unit image is obtained from the plurality of processed divided unit image data. A creation step for generating data, and an integration step for generating a unit image by integrating a plurality of division unit image data created from the plurality of processed division unit image data in the creation step are executed.

Preferably, the image decoding program, if the character image data in which access information indicating whether or not that is rotated 90 degrees at the time of encoding, the character image data is rotated 90 degrees at the time of encoding, A step of rotating the generated character image data by 90 degrees in the opposite direction to the rotation direction at the time of encoding is further executed.

  In the image coding apparatus according to the present invention, data of a similar size, represented by a character image (character image data), is conspicuous in image data having a characteristic that is arranged at a constant period, particularly in Chinese characters. Image data having a feature that a lot of line segments in a specific direction are included in the data can be encoded with a small amount of calculation with high efficiency.

  In the image decoding apparatus according to the present invention, the data encoded by the image encoding apparatus can be decoded with a small amount of calculation.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same.

  The image encoding device and the image decoding device according to the present embodiment may be realized by a computer such as a personal computer as an information processing device, or mounted in a portable device as a text processing device. It may be. In the present embodiment, it is assumed that the image encoding apparatus is mounted on a personal computer (hereinafter abbreviated as a PC) as an information processing apparatus. Further, the image decoding device is assumed to be mounted on a mobile phone as an example of a mobile device as a text processing device. Other specific examples of the text processing device include PDAs (Personal Digital Assistants), portable game devices, and home appliances equipped with display devices.

<1. Image Encoding Device>
[First Embodiment]
FIG. 48 is a diagram illustrating a specific example of the hardware configuration of the PC 3 as the information processing apparatus equipped with the image encoding device according to the present embodiment, and illustrates a specific example of the general hardware configuration of the PC. It is a block diagram.

  Referring to FIG. 48, the PC 3 is a CPU 101 for controlling the entire apparatus, a ROM 103, a RAM 105, a hard disk drive 107, a flexible disk drive (FDD), a CD-ROM (Compact Disk-Read Only Memory). ) A reading unit 109 that reads information from the recording medium 2 such as a drive, an input unit 111 configured by a keyboard, a mouse, and the like, a communication unit 113 for communicating with the outside, and a display unit 115 are configured.

  The image encoding apparatus according to the present embodiment is configured by hardware of the PC 3 and software that is stored in a storage unit such as the ROM 103 and executed by the CPU 101. A function for performing an image encoding process to be described later is the CPU 101. Is mainly formed in the CPU 101 by reading and executing a program stored in a storage unit such as the ROM 103. Alternatively, at least a part of the above functions may be configured by the hardware of the PC 3 shown in FIG.

  FIG. 2 is a block diagram illustrating a specific example of a functional configuration for functioning as an image encoding device in the PC 3 according to the present embodiment and performing image encoding processing. The image encoding device according to the first embodiment encodes a sequence of character image data corresponding to different character codes using a difference between lines for each sequence of words.

  Referring to FIG. 2, the above-described functions of the image encoding device include a controller 1201, an image data memory 1202, a processed divided image data memory 1203, an entropy encoding unit 1204, an encoded data memory 1205, an access table data generation unit 1206, An access table data memory 1207, a character identification information / glyph number correspondence rule memory 1208, and an image processing unit 1209 are configured, and each component is connected to each other and the outside via a data bus 1210.

  FIG. 3 is a block diagram illustrating a specific example of the configuration of the image processing unit 1209. Referring to FIG. 3, image processing unit 1209 includes an image calculation unit 3801, a character image data memory 3802, a divided character image data memory 3803, and a processed divided character image data memory 3804. Each component is a data They are connected to each other and the outside via a bus 3805.

  Further, FIG. 4 is a block diagram showing a specific example of the configuration of the access table data generation unit 1206. Referring to FIG. 4, access table data generation unit 1206 includes a character identification information / glyph number conversion data generation unit 2201 and a glyph number / offset information conversion data generation unit 2202, and each component is a data bus. They are connected to each other and to the outside through 2203.

  The image data memory 1202 includes a predetermined area of a storage unit such as the ROM 103, and image data acquired by an acquisition unit (not shown) is input (loaded) to the image data memory 1202. The acquisition unit is not limited to a specific means in the present invention, and examples include a reading unit 109 that reads data from a recording medium such as a CD-ROM, and a communication unit 113 that receives data transmitted from another device.

  Here, a word is used as a unit for reading data into the memory. A word or a multiple of a word and the size of image data (hereinafter referred to as character image data) constituting one character may not match. Therefore, for example, when character image data for one character is read in two words, the boundary between words (word boundary) does not coincide with the center of the character in the data written in the memory. This will be specifically described with reference to FIG. In FIG. 5 and the following embodiments, it is assumed that words are arranged in the horizontal direction. The number of vertical and horizontal dots in the character image data is assumed to be constant. However, in the present invention, the size of the image data to be processed and the size of the character data are not limited to a specific size, and in the following example, the word size is 8 bits as one specific example. The size of the character image data constituting one character is 11 dots in both vertical and horizontal dots (hereinafter, sometimes referred to as 11 × 11 font). Then, as shown in FIG. 5, it is assumed that individual character data is stored as a binary image of 2 bytes wide and 11 dots long by offsetting 1 dot to the left. In the following, it is assumed that the image line starts from 0 when counting. Therefore, the first line is “0th line”. FIG. 5 shows a specific example of character image data 101 which is a binary image having a size of 11 dots × 11 dots. The character image data 101 for one character shown in FIG. 5 is composed of 16 bits × 11 lines corresponding to two words, and characters on the left side are always 11 bits × 11 dots at least 1 bit apart. Represented. Depending on the shape of the character, there may be little or no dot (hereinafter “black dot”) constituting the character in the character image data constituting one character. Here, the leftmost dot is assumed to be MSB (Most Significant Bit) as the byte value of the binary image. In the following description, black dots are set to 1 and other dots are set to 0. For example, in the case of data 102 in FIG. 12 described later, the value of the 0th line is 0X02 in hexadecimal.

  FIG. 6 is a diagram illustrating a specific example of image data that is a binary image stored in the image data memory 1202. It is assumed that the image data stored in the image data memory 1202 is image data formed by connecting a plurality of character image data constituting one character in the vertical direction as shown in FIG.

  The character identification information / glyph number correspondence rule memory 1208 includes a predetermined area of a storage unit such as the ROM 103, and stores character identification information / glyph number correspondence rules indicating correspondence between character identification information and glyph numbers, which will be described later.

  Character identification information indicates information for identifying a character, and specifically indicates a character code, a typeface, and the like. The glyph number indicates information specifying character image data stored in the image data memory 1202, and specifically indicates a number starting from 0 added to each character image data stored in the image data memory 1202. In the following description, the glyph number is also the order in which each character image data is encoded. Here, “glyph” is used to mean a character shape represented by a character image.

  The character identification information / glyph number correspondence rule specifies the correspondence between each character image data stored in the image data memory 1202 and the character identification information. Specifically, as shown in FIG. 10 is a table showing correspondences between character codes as identification information, typeface identification information as character identification information, and glyph numbers that specify character image data stored in the image data memory 1202. In the following specific examples, the character identification information is a 2-byte shift JIS code and 1-bit typeface designation information (Gothic type is represented by 0 and Mincho type is represented by 1). In this specific example, it is assumed that characters having different font sizes have different encoded data. Therefore, the font size is not included in the character identification information.

  As specified in the table shown in FIG. 7, even if the character code is the same, if the typeface is different, it may correspond to a different glyph. Alternatively, different character codes may correspond to the same glyph.

  The character image data memory 3802, the divided character image data memory 3803, and the processed divided character image data memory 3804 of the image processing unit 1209 are configured by predetermined areas of a storage unit such as the ROM 103.

  Character image data for one character is read from the image data stored in the image data memory 1202 by the image calculation unit 3801 and stored in the character image data memory 3802. The character image data stored in the character image data memory 3802 is divided in the vertical direction at the byte boundary in the horizontal direction by the image calculation unit 3801 and stored in the divided character image data memory 3803 as “divided character image data”. . Since images are generally arranged in raster order, when they are divided at byte boundaries, the addresses are discontinuous in character image data, and the addresses adjacent in the vertical direction are continuous on one divided character image data. Will come to do.

  In the present invention, the character image data dividing method is not limited to a specific method, and the above method is one specific example. The division method is preferably a method that considers the dot configuration of the character image data as in the above specific example. By dividing the character image data by such a dividing method, the distribution can be concentrated on a specific value in encoding as will be described later.

  Further, since the division method in the present embodiment is divided in units of bytes (8 bits), the CPU can easily perform processing in units of normal bytes. Of course, a specific example of this division method is based on the premise that the byte arrangement on the image is arranged with the bits constituting the byte in the horizontal direction. Therefore, if this premise is different, the dividing method is preferably a dividing method that can be easily processed by the CPU, instead of the dividing method of this specific example.

  For the divided character image data stored in the divided character image data memory 3803, an exclusive OR is calculated in the image calculation unit 3801, and the calculation result is stored in the processed divided character image data memory 3804 as “processed divided character image data”. Is done.

  Here, as is widely known, exclusive OR is an operation that sets 0 when two bits match and 1 when they do not match. Here, since each character is closed, the first line uses the 0th line extracted from the divided character image data as the input data without using the exclusive OR.

Therefore, if the exclusive OR of A and B is represented by the symbol “^”,
For n = 0,
(Nth line of processed divided character image data) = (nth line of divided character image data)
For n ≧ 1,
(Nth line of processed divided character image data) = ((n-1) th line of divided character image data) ^ (nth line of divided character image data)
It becomes.

  In this way, the 0th line of the divided character image data is copied to the processed divided image data as it is, and the exclusive OR is calculated for the remaining lines, so that it is necessary to decode other characters when decoding one character. Each character can be decoded independently.

  Here, an exclusive OR between adjacent lines is used as a method for obtaining a difference, but this method is, of course, a specific example, and the present invention is not limited to a specific method. The method of obtaining the difference may not be exclusive OR as long as the conversion increases the frequency of a specific value without losing the original information (without losing reversibility). Depending on the contents, an exclusive OR between distant lines may be used instead of adjacent lines. In particular, the latter can be used to increase the frequency of a specific value (for example, to increase the bias in the distribution of values) (for example, when it is known that a line with similar contents appears periodically). It is effective if possible.

  The processed divided image data memory 1203 includes a predetermined area of a storage unit such as the ROM 103. The processed divided character image data stored in the processed divided character image data memory 3804 is output to the processed divided image data memory 1203 by the image calculation unit 3801 and stored therein.

  The encoded data memory 1205 includes a predetermined area of a storage unit such as the ROM 103. The processed divided image stored in the processed divided image data memory 1203 is entropy encoded by the entropy encoding unit 1204 and stored in the encoded data memory 1205 as “encoded data”.

  Note that the encoding method in the entropy encoding unit 1204 is not limited to a specific method in the present invention, and any known technique may be employed. Specific examples of the encoding method include fixed Huffman encoding (hereinafter simply referred to as “Huffman encoding”), arithmetic encoding, and the like. The image encoding apparatus according to the present embodiment performs Huffman encoding. Shall be. The advantage of Huffman coding is that the amount of calculation for decoding is small. Further, it is preferable that the unit for performing entropy encoding is not the processed divided character image data but the processed divided image data larger than the character unit. In general, if character image data is a range encoded as a lump of data (in Huffman encoding, the range of data encoded by sharing a Huffman table), the overhead tends to increase with respect to the total amount of data. It is. Here, the overhead means a necessary data amount other than the code corresponding to the original data. For example, if Huffman coding is employed, the amount of data in the Huffman table corresponds to overhead. Needless to say, when an encoding method in which the overhead is sufficiently small with respect to the total amount of data is adopted, the range encoded as a lump of data may be processed divided character image data.

  The access table data memory 1207 is configured with a predetermined area of a storage unit such as the ROM 103. The access table data generation unit 1206 generates access table data for accessing the encoded data stored in the encoded data memory 1205 and stores it in the access table data memory 1207.

  The access table data defines the correspondence between the character identification information and information indicating where the character specified by the character identification information corresponds to the code from where to where on the encoded data (this information is referred to as offset information). And is stored together with the encoded data. The access table data is used in the decryption process described later. As a specific example, as shown in FIG. 8, the access table data includes character identification information in a glyph number indicating the number of glyphs in the encoded data (hereinafter referred to as the 0th glyph). The data includes character identification information / glyph number conversion data 1401 for conversion and glyph number / offset information conversion data 1402 for converting the glyph number into offset information.

  In general, in encoding for reducing the data capacity, the encoded data length differs even for image data having the same data length. Therefore, the data position on the encoded data corresponding to the data corresponding to each character cannot be obtained from the glyph number by simple calculation, and offset information is required.

  More specifically, the character identification information / glyph number conversion data generation unit 2201 of the access table data generation unit 1206 acquires an internal character code based on the character identification information (note that “acquisition” here is calculated) The same applies hereinafter). The internal character code refers to a value indicating which character code in the image encoding device is the character specified by the character identification information in order to improve data access efficiency. Here, even if the character code is the same, the internal character code is different if the typeface designation information is different.

  The glyph number / offset information conversion data generation unit 2202 of the access table data generation unit 1206 generates glyph number / offset information conversion data and writes it into the access table data memory 1207. The glyph number / offset information conversion data refers to a value representing the correspondence between the glyph number and the offset information on the encoded data for finding the code data corresponding to each glyph from the glyph number.

  FIG. 9 is a flowchart showing an encoding process in the image encoding apparatus according to the present embodiment. The processing shown in the flowchart of FIG. 9 is realized by the control unit 120 reading and executing a program stored in the storage unit such as the ROM 103, and the controller 1201 controlling each unit shown in FIG.

  Referring to FIG. 9, first, image data is input (loaded) to image data memory 1202 by controller 1201 (step S1301). Here, the following description will be made assuming that the image data (11 × 11 font) shown in FIG. 6 is loaded as a specific example. Further, the controller 1201 inputs (loads) the aforementioned character identification information / glyph number correspondence rule to the character identification information / glyph number correspondence rule memory 1208 (step S1302). Here, the following description will be given on the assumption that the character identification information / glyph number correspondence rule shown in FIG. 7 is loaded as a specific example.

  The image calculation unit 3801 of the controller 1201 obtains divided character image data by dividing the character image data extracted from the image data stored in the image data memory 1203 in step S1301 in the vertical direction by the horizontal byte boundary (step S1301). S1303). From the divided character image data obtained in step S1303, an exclusive OR is calculated in the image processing unit 1209, and the calculation result is stored in the processed divided image data memory 1203 as processed divided character image data (step S1304). The processed divided image data and the processed divided image data memory 1203 already store processed divided character image data corresponding to the character image data that has already been processed. In step S1303, the processed divided character image data is added to the end of the already stored processed divided character image data and stored in the processed divided image data memory 1203. “Processed divided image data” refers to the processed divided character image data stored in this manner, and there are as many character image data as the number of characters image data divided in step S1303. Therefore, when the image data shown in FIG. 6 is loaded, two processed divided image data exist. FIG. 49 and FIG. 50 show specific examples before and after the addition of one character of processed divided character image data in step S1304, where two characters of processed divided character image data have already been stored. FIG. As described above, there are two pieces of processed divided image data corresponding to the division of character image data into two in step S1303. However, one piece of processed divided image data is processed for the other processed divided image data. FIGS. 51 and 52 show specific examples before and after the character image data is added.

  If all the characters included in the image data loaded in step S1301 have been processed (YES in step S1305), the process proceeds to step S1306. If not processed (NO in step S1305), the process returns to step S1302. .

  In step S <b> 1306, the entropy encoding unit 1204 performs entropy encoding processing on the processed divided image data stored in the processed divided image data memory 1203 and stores the encoded data in the encoded data memory 1205.

  If processing has been completed for all the processed divided image data obtained from the image data loaded in step S1301 (YES in step S1307), the process proceeds to step S1308; otherwise (in step S1307). NO), the process returns to step S1306.

  In step S 1308, the access table data generation unit 1206 generates access table data for accessing the encoded data stored in the encoded data memory 1205, and stores it in the access table data memory 1207.

  The encoded data stored in the encoded data memory 1205 is output from the image encoding apparatus by the controller 1201 as the encoding result of the image data (step S1309). Further, the access table data stored in the access table data memory 1207 is also output from the image encoding apparatus together with the encoded data (step S1310), and the process ends.

  FIG. 10 is a flowchart showing the image data dividing process in step S1303.

  Referring to FIG. 10, first, image calculation unit 3801 reads character image data for one character from the image data loaded in image data memory 1202 in step S1301, and stores it in character image data memory 3802 (see FIG. 10). Step S3901).

  When the image data loaded in the image data memory 1202 is the image data shown in FIG. 6, in step S3901, the character image data shown in FIGS. 3802.

  Next, the image calculation unit 3801 divides the character image data stored in the character image data memory 3802 in the vertical direction, stores the divided character image data in the divided character image data memory 3803 (step S3902), and performs processing. The process proceeds to step S1304.

  Specifically, the character image data obtained in step S3901 is the character image data obtained by dividing the loaded image data shown in FIG. 11A, that is, the diagram described above. In the case of the data 101 shown in FIG. 5, the divided character image data becomes the data 102 shown in FIG. 12 and the data 103 shown in FIG. 13 by being divided by the image calculation unit 3801 in step S3902. In the case of the character image data having the configuration shown in FIG. 5, no value is entered in the leftmost bit. Therefore, as shown in FIGS. 12 and 13, the divided character image data is divided in such a direction. The left-side data 102 and the right-side data 103 differ greatly in the distribution of the values of the individual bytes comprising the dots included in the horizontal line constituting the image.

  As for the byte value of the data 103 in FIG. 13, since the characters are arranged as described above, the lower 4 bits always have a value of 0. That is, there are only 16 types of byte values of the data 103 at the maximum. Therefore, dividing the character image data in the vertical direction in the image calculation unit 3801 contributes to the improvement of the encoding efficiency.

  FIG. 14 shows an example of character image data having a size of 23 dots × 23 dots. Here, the left byte 201 has an MSB of 0 at all times, and therefore there are only 128 types of byte values. Absent. That is, since the left byte 201 has a different value distribution from the central byte 202 and the right byte 203, dividing the character image data in the vertical direction in the image calculation unit 3801 contributes to improving the coding efficiency.

  It is particularly preferable to divide the character image data in the vertical direction, particularly when the characters are arranged on the character image data according to the word (byte) boundary (boundary) as in the above specific example. is there. A specific example of image data that is not so is shown in FIG. On the image data shown in FIG. 15, character image data is arranged across the word boundaries 701 and 702. However, even in such a case, it is possible to convert the character so that it does not cross the word boundary by an appropriate bit operation (shift or the like).

  FIG. 16 is a flowchart showing the exclusive OR calculation process in step S1304.

  Referring to FIG. 16, first, image operation unit 3801 calculates an exclusive OR for the divided character image data stored in divided character image data memory 3803 in step S3901, and processes the processed divided character image data. The divided character image data memory 3804 is stored (step S4001). Specifically, when the exclusive OR of the divided character image data 102 shown in FIG. 12 is calculated, the processed divided character image data 601 shown in FIG. 17 is obtained. Then, the image calculation unit 3801 outputs the processed divided character image data stored in the processed divided character image data memory 3804 to the processed divided image data memory 1203 (step S4002).

  If the process of calculating the exclusive OR for all the divided character image data obtained from the image data loaded in step S1301 has been completed (YES in step S4003), the process is terminated and the process proceeds to step S1305. . Otherwise (NO in step S4003), the process returns to step S4001.

  The access table generation processing in step S1308 will be described with reference to the flowchart of FIG.

  The simplest configuration of the character identification information / glyph number conversion data 1401 included in the access table is a configuration that defines a correspondence between a character code and a glyph number. However, when the character identification information / glyph number conversion data 1401 has such a configuration, the data size of the character identification information / glyph number conversion data 1401 is (number of characters) × (bit length necessary to store the character code). Since efficient encoding cannot be achieved, the following configuration is preferable.

Now assume the following:
(Assumption 1) Character identification information and glyphs are not necessarily associated one-to-one, and one glyph may be associated with a plurality of codes.
(Assumption 2) There may be character identification information not associated with glyphs.
(Assumption 3) The majority of glyphs are associated with the character identification information on a one-to-one basis.
(Assumption 4) The character codes are locally continuous.
(Assumption 5) The glyph data is arranged in ascending order (from smallest to largest) of the corresponding internal character codes (described later). However, when there are a plurality of corresponding internal character codes, the smallest one is taken.

  The above (Assumption 1) is the case where font data is displayed on the target display device even though it can be distinguished by the character identification information (character code) such as the Greek letter “L” and the Latin alphabet “P”. This is an assumption in consideration of the possibility that the encoded data can be reduced by using the common glyph data when it cannot be distinguished as glyphs.

  The above (Assumption 2) assumes the case where there is no glyph depending on the size (for example, complex characters that exist only at a specific size, that is, complex characters that cannot be displayed without a certain size) Applicable to shape characters).

  The above (Assumption 3) is an assumption that most character identification information is associated with glyph data on a one-to-one basis even under the assumptions of (Assumption 1) and (Assumption 2).

  The above (Assumption 4) is an assumption that the character codes are not all discontinuous, as is typically seen in the shift JIS code, but the characters are associated with continuous codes. This assumption indicates that a character code and typeface identification information can be easily converted into an internal character code with a relatively small number of conditional expressions, as will be described later.

  The above (Assumption 5) is a condition that is satisfied if configured in such a manner, and is intended to make it easy to create access table data that can be accessed at high speed by encoding, which will be described later. The example of the character identification information / glyph number correspondence rule shown in FIG. 7 also satisfies this assumption.

  Based on the above assumptions, in this embodiment, it is assumed that the character identification information / glyph number conversion data 1401 has the configuration shown in FIG. That is, referring to FIG. 19, the character identification information / glyph number conversion data 1401 includes a status table 1501, a first auxiliary table 1502, and a second auxiliary table 1503.

  Referring to FIG. 18, when generating access table data, first, the character identification information / glyph number conversion data generation unit 2201 acquires an internal character code for the target character based on the character identification information ( Step S2301). Here, the specific correspondence between the character code as the character identification information and the internal character code is the correspondence shown in FIG. In FIG. 20, for convenience of explanation, there are only six character codes of 0x8250 to 0x8251 and 0x8260 to 0x8262. In FIG. 20, it can be read that the above (Assumption 4) is established.

  As one specific example of the technique for converting a character code and typeface identification information into an internal character code by using some conditional statements, FIG. 21 shows a variable code indicating a character code and a variable type indicating typeface identification information. To C-language source code to be converted into a variable internal_code indicating the internal character code. The technique used in step S2301 is not limited to a specific technique. For example, an internal character code is obtained using a technique as shown in FIG.

  Next, the character identification information / glyph number conversion data generation unit 2201 generates a status table from the character identification information / glyph number correspondence rule stored in the character identification information / glyph number correspondence rule memory 1208 and the internal character code. The data is written in the access table data memory 1207 (step S2302).

When the character identification information / glyph number correspondence rule is as shown in FIG. 7, and the correspondence between the character code as the character identification information and the internal character code is as shown in FIG. 20, in step S2302, The status table shown in FIG. 22 is generated. The status table is a table indicating glyph allocation states corresponding to the internal character codes arranged in ascending order. Specifically, referring to FIG. 22, the status table 1501 includes the following three types. One of the values is specified for each internal character code:
0 ... No glyph is assigned to the internal character code,
1 ... There is only one character code corresponding to the glyph assigned to the internal character code, or there are two or more character codes, but the glyph appears in the status table 1501 for the first time.
2... There are two or more internal character codes corresponding to the glyphs assigned to the internal character code.

    In the status table shown in FIG. 22, 1 is given as a value to the internal character codes 3, 9, 4, 10, 5, and 11, and therefore, referring to FIG. A ”, Mincho“ A ”, Gothic“ B ”, Mincho“ B ”, Gothic“ C ”, and Mincho“ C ”have independent glyphs (in the internal character code). It can be seen that there is only one corresponding glyph). Further, since 2 is assigned to the internal character codes 6 and 8, it is indicated that a glyph common to other internal character codes is used. It cannot be determined from this table alone whether the glyph common to the internal character code is used. However, referring to FIGS. 7 and 20 together, the glyph common to the internal character codes 0 and 2 is used. You can see that Therefore, the value of the table corresponding to the internal character codes 0 and 2 is 1 because the above-mentioned “there are two or more character codes corresponding to the glyphs assigned to the internal character code but the status table This is the first time the glyph comes out at 1501 ". Further, since “0” is given to the internal character code 7, it is indicated that there is no Gothic “2” glyph.

  Next, the character identification information / glyph number conversion data generation unit 2201 generates a first auxiliary table and writes it in the access table data memory 1207 (step S2303). Here, the first auxiliary table is a table describing glyph numbers corresponding to some of the internal character codes. A specific example of the first auxiliary table 1502 in FIG. 19 is a table describing the correspondence between some of the internal character codes and glyph numbers shown in FIG. The first auxiliary table 1502 is a table used when decoding the encoded data, and how it is used will be described later.

  The configuration of the first auxiliary table 1502 will be described. When 1 is assigned to the value of the status table 1501, the number of such data has been checked so far, and the obtained result is the corresponding glyph number (because there is the above (Assumption 5)). .) The first auxiliary table stores the result of calculating the corresponding glyph number as described above for some of the internal character codes.

  In the first auxiliary table 1502 shown in FIG. 23, in order to make the access to the first auxiliary table more efficient, the correspondence between glyph numbers is described for internal character codes at equal intervals (as a specific example, in increments of 5). Needless to say, the intervals may be uneven. Even if the interval is shorter than the specific example, if the data size of the first auxiliary table is sufficiently small, there is a merit in improving access efficiency. Further, the countermeasure when “0” or “2” is defined in the status table 1501 for the internal character code to be described in the first auxiliary table is not limited to a specific countermeasure. What is necessary is just to use the internal character code | cord | chord which is an internal character code before the code | symbol and in which the effective value was prescribed | regulated.

  Also, instead of the status table 1501 shown in FIG. 22, the status table is configured in advance so that the glyph number is described as shown in FIG. 24, so that the first auxiliary table is generated in step S2303. It can be unnecessary. However, if the status table is configured as shown in FIG. 24, the amount of data is (the number of bits representing the glyph number) × (the number of characters in which “1” is defined in the status table). A status table is not preferable because it is added to the encoded data.

  Next, the character identification information / glyph number conversion data generation unit 2201 generates the second auxiliary table 1503 and writes it in the access table data memory 1207 (step S2304). Here, the second auxiliary table refers to an internal character code in which “2” is defined in the status table 1501, that is, an internal character code corresponding to an assigned glyph, with respect to the corresponding glyph. This is a table describing numbers. A specific example of the second auxiliary table 1503 in the case of the status table 1501 of FIG. 22 is the table shown in FIG. The second auxiliary table is a table used when decoding the encoded data, and specifically how to use will be described later. According to the above assumption (3), it is assumed that there are few internal character codes in which “2” is defined in the status table 1501, so that the corresponding glyph numbers for all the internal character codes in which “2” is defined are described. Even if the table is generated, it is considered that the coding efficiency is maintained.

  In the above specific example, the correspondence between the internal character code and the glyph number is described in the second auxiliary table 1503. However, as the access key, the character identification information is used instead of the internal character code. And the glyph number may be described. The same applies to the first auxiliary table 1502.

  The character identification information / glyph number conversion data generated by the character identification information / glyph number conversion data generation unit 2201 is one specific example, and the conversion data generated here is the character identification as described above. It is not limited to information / glyph number conversion data. The point here is whether the correspondence between the character identification information (or the internal character code uniquely determined therefrom) and the glyph number or glyph is one-to-one or not (or how many glyph numbers or glyphs are The number of glyph numbers or glyphs corresponding to the character identification information) is generated. Another important point is that the image decoding apparatus, which will be described later, refers to a different table according to the determination result for the generated data, thereby reducing the data capacity required for itself. Character identification information / glyph number conversion data is configured so that character identification information (or internal character code) can be converted to glyph numbers at high speed (glyph data is specified) while keeping small. Specifically, in the present embodiment, the first auxiliary table 1502 is referred to when the character identification information (internal character code) has a one-to-one correspondence with the glyph, and the second auxiliary table otherwise. The character identification information / glyph number conversion data generation unit 2201 generates character identification information / glyph number conversion data configured to be able to refer to 1503. Further, the first auxiliary table 1502 is a subset of a correspondence table between character identification information (or internal character codes) and glyph numbers.

  Next, the glyph number / offset information conversion data generation unit 2202 generates glyph number / offset information conversion data for each processed divided image data and writes it in the access table data memory 1207 (step S2305). The character identification information / offset information conversion data is not related to the division, but the glyph number / offset information conversion data indicating the offset in the encoded data accesses data corresponding to the number of encoded glyphs × the number of divisions. I have information.

  In the specific example of the above configuration, the glyph number / offset information conversion data is obtained by converting the position on the encoded data of the data corresponding to the encoded divided processed character data from the glyph number, thereby converting the character image data. The position on the encoded data is specified. More generally, it can be said that the glyph information / offset information conversion data is information for obtaining the position of the encoded character image data on the encoded data from the glyph number. In fact, if the encoded data is arranged for each part corresponding to each (encoded) character image data instead of each (encoded) processed divided image data, the glyph number / offset information conversion data Is information for directly obtaining the position on the encoded data of the character image character image data encoded from the glyph number. Here, although the creation method of the glyph number / offset information conversion data is not described in detail, for example, the encoded data corresponding to each division is searched from the beginning, and the position that becomes the boundary of the processed divided character image is offset. Since the information may be recorded, it is not limited to a specific method. Of course, it is also conceivable to devise a glyph number / offset information conversion data so that processing at the time of decoding can be performed at high speed.

  If the process has been completed for all the divided image data obtained from the image data loaded in step S1301 (YES in step S2306), the process proceeds to step S1309; otherwise (step S2306). In step S2307, the process moves to the next divided image data, and the process returns to step S2305.

  By performing the above-described processing in the image coding apparatus according to the present embodiment, a small amount of calculation is performed using the feature that data of similar size, which is found in character image data, is arranged at a fixed period. Highly efficient encoding can be performed in a quantity. That is, by dividing the character image data in the direction corresponding to the dot configuration of the character image data to be encoded, the distribution probability of the byte value is more reflected, and the encoding efficiency can be improved.

  Further, by adding the correspondence between the encoded data, the internal character code, and the character identification information to the encoded data as a small-size table, the image decoding apparatus described below can perform decoding with a small amount of calculation. .

  In the above description, each character image data is divided and encoded perpendicular to the line direction. However, the above method is one specific example of the present invention, and another specific example is as follows. There is also a method of creating “divided image data” by performing division perpendicular to the line direction, and then creating “processed divided image data” by taking the difference between the lines for each portion corresponding to each character image data. It is done. An embodiment employing such a method is also one of variations of the present invention.

  In this embodiment, the image data is font data composed of character image data. However, the image data to be processed by the information processing apparatus according to the present invention is not limited to character image data. Any image data may be used as long as the unit image data has a constant size and is continuous. In particular, in that case, the “character image data” in the above embodiment is “unit image data”, the “divided character image data” is “divided unit image data”, and the “processed divided character image data” is “processing divided unit”. By appropriately replacing “image data” or the like, it is possible to explain the operation / configuration when image data other than character image data is processed. The same applies to other embodiments.

[Second Embodiment]
As further features seen in the binary image of the character image data, there are character image data mainly composed of vertical lines as shown in FIG. 26 and character image data mainly composed of horizontal lines as shown in FIG. These features are particularly noticeable when the characters are Chinese characters.

  When the input data is the character image data shown in FIG. 26, the output data shown in FIG. 28 is obtained by calculating the exclusive OR for each word arranged horizontally. As shown in FIG. 28, in the case of the character image data as shown in FIG. 26, when the exclusive OR is calculated, there are many words that become 0 words (words in which all bits are 0). Therefore, the frequency of 0 words can be increased without losing information by exclusive OR, and the encoding efficiency can be increased.

  On the other hand, when the input data is the character image data shown in FIG. 27, even if the exclusive OR for each word arranged horizontally is calculated, the output data is as described above as shown in FIG. There is no effect of increasing the frequency of the value of a specific word.

  An image encoding apparatus according to a second embodiment of the present invention is an apparatus that encodes a series of character font data corresponding to different character codes using a difference between lines for each series of words. Encoding is performed using the above characteristics of character image data. For this reason, the image coding apparatus according to the second embodiment of the present invention is characterized in that the character image data is rotated so that the data amount of the coded data becomes smaller at the time of coding. This is a difference from the image coding apparatus according to the first embodiment. Therefore, the difference will be mainly described below.

  FIG. 30 is a block diagram showing a specific example of a functional configuration for functioning as an image encoding device in the PC 3 according to the present embodiment and performing image encoding processing.

  Referring to FIG. 30, the functions of the image coding apparatus according to the present embodiment are added to the functions included in the functions of the image coding apparatus according to the first embodiment shown in FIG. The flag data memory 2410 is included.

  Further, FIG. 31 is a block diagram showing a specific example of the configuration of the image processing unit 1209 according to the present embodiment. Referring to FIG. 31, an image processing unit 1209 according to the present embodiment includes an image calculation unit 2701, a first character image data memory 2702, a second character image data memory 2703, a first divided character image data memory 2704, The divided character image data memory 2705, the first processed divided character image data memory 2706, the second processed divided character image data memory 2707, and the capacity predicting unit 2708 are configured, and each component is mutually connected via the data bus 2709. Also connected to the outside.

  In the present embodiment, character image data for one character is read out from the image data stored in the image data memory 1202 by the image calculation unit 2701, and the first character image data memory is stored as “first character image data”. 2702 is stored. The first character image data stored in the first character image data memory 2702 is divided in the vertical direction at the byte boundary in the horizontal direction by the image calculation unit 2701, and the first divided character image data is obtained as “first divided character image data”. It is stored in the image data memory 2704.

  The first divided character image data stored in the first divided character image data memory 2704 is further rotated in a predetermined direction by the image calculation unit 2701 to obtain “second character image data” as the second character image data memory. 2703 is stored. The second character image data stored in the second character image data memory 2703 is divided in the vertical direction at the byte boundary in the horizontal direction by the image calculation unit 2701, and the second divided character image data is obtained as “second divided character image data”. It is stored in the image data memory 2705. Here, the “predetermined direction” is 90 degrees clockwise.

  The image of one character stored in the image data memory 2409 is XORed with the divided image stored in the first divided character image data memory 2704 (hereinafter sometimes referred to as “processed divided character image”). The first processed divided character image data memory 2706 is stored.

  With respect to the first divided character image data stored in the first divided character image data memory 2704, an exclusive OR is calculated in the image calculation unit 2701, and the calculation result is “first processed divided character image data” as the first processed character. The divided character image data memory 2706 is stored.

  Similarly, with respect to the second divided character image data stored in the second divided character image data memory 2705, an exclusive OR is calculated by the image calculation unit 2701, and the calculation result is “second processed divided character image data”. The second processed divided character image data memory 2707 is stored.

  The capacity prediction unit 2708 encodes the capacity of the first character image data stored in the first character image data memory 2702 and the second processed divided character image data stored in the second processed divided character image data memory 2707. Are predicted, and the predicted results are compared. According to the comparison result in the capacity prediction unit 2708, the first processed divided character image data stored in the first processed divided character image data memory 2706 or the second processed divided character stored in the second processed divided character image data memory 2707 Character image data is output. In addition, a flag indicating the comparison result in the capacity prediction unit 2708 is stored in the flag data memory 2410 by the image calculation unit 2701.

  FIG. 32 is a flowchart illustrating an encoding process in the image encoding device according to the second embodiment. The processing shown in the flowchart of FIG. 32 is also realized by the CPU 101 reading out and executing a program stored in the storage unit such as the ROM 103, and the controller 1201 controlling each unit shown in FIG. Note that the encoding process in the second embodiment shown in FIG. 32 is substantially the same as the encoding process in the second embodiment shown in the flowchart of FIG. 9, and the following points are different. . That is, instead of the processing in step S1303 and the processing in step S1304 in the first embodiment, the processing in step S2503 and the processing in step S2504 are executed in the encoding processing in the second embodiment. . In addition to the above processing, the processing in step S2511 is executed.

  FIG. 33 is a flowchart showing image data division processing in step S2503.

  Referring to FIG. 33, first, image calculation unit 2701 reads character image data for one character from the image data loaded into image data memory 1202 in step S1301, and converts the first character image data to the first character image data. The image data is stored in the image data memory 2702 (step S3701).

  Next, the image calculation unit 2701 generates the first divided character image data by dividing the first character image data stored in the first character image data memory 2702 in the vertical direction by the horizontal byte boundary. The divided character image data memory 2704 is stored (step S3702). The division method here may be the same method as described in the first embodiment.

  Next, the image calculation unit 2701 rotates the first character image data stored in the first character image data memory 2702 by 90 degrees clockwise to generate second character image data, and the second character image data memory 2703. (Step S3703).

  Next, the image calculation unit 2701 generates the second divided character image data by dividing the second character image data stored in the second character image data memory 2703 in the vertical direction by the horizontal byte boundary. The divided character image data memory 2705 is stored (step S3704). The dividing method here may be the same method as described in the first embodiment.

Then, the process ends, and the process proceeds to step S2504.
FIG. 34 is a flowchart showing the exclusive OR calculation process in step S2504.

  Referring to FIG. 34, first, image calculation unit 2701 calculates an exclusive OR for the first divided character image data stored in first divided character image data memory 2704 in step S3702, and performs first processing. The divided character image data is stored in the first processed divided character image data memory 2706 (step S2801). The exclusive OR calculation method may be the same as the method described in the first embodiment.

  If the process of calculating the exclusive OR for all the first divided character image data obtained from the image data loaded in step S1301 has been completed (YES in step S2802), the process proceeds to step S2803. If not (NO in step S2802), the process returns to step S2801.

  In step S2803, the capacity prediction unit 2708 predicts the encoded capacity of the first character image data stored in the first character image data memory 2702 (step S2803). The prediction method in step S2803 only needs to be consistent with the encoding method in step S1306, and is not limited to a specific method in the present invention. As a specific example, the entropy of the first processed divided character image data obtained from the first character image data stored in the first character image data memory 2702 by adopting the entropy encoding method in step S1306 above. The method of summing up is mentioned. The target value to be predicted is the amount of increase in the code data amount (herein referred to as “limit code amount”) by encoding the individual first processed divided character image data as the prediction method in step S2803. However, in this specific example, the range encoded as a lump of data is not processed divided character image data, and it is not easy to directly calculate this, so instead, the entropy prediction value of the first processed divided character image data is set to It is used. In any case, what is important is that the predicted value used here is consistent with the encoding method in step S1306 (there is a reason that the predicted value is sufficiently close to the target value). In this specific example, since Huffman coding is used as the coding method, it can be said that there is a reason that a value sufficiently close to the limit code amount can be obtained by using entropy as the prediction value of the limit code amount. . Of course, as long as the encoding method is such that the target value to be predicted (limit code amount) can be easily obtained, the limit code amount may be used, and this is a variation of the present invention.

  Next, the image computing unit 2701 calculates an exclusive OR of the second divided character image data stored in the second divided character image data memory 2705, and the obtained second processed divided character image data is stored in the second. The processed divided character image data memory 2707 is stored (step S2804).

  If the process of calculating the exclusive OR for all the second divided character image data obtained from the image data loaded in step S1301 has been completed (YES in step S2805), the process proceeds to step S2806, where If not, the process returns to step S2804.

  In step S2806, the capacity predicting unit 2708 predicts the encoded capacity of the second processed divided character image data 2707 stored in the second processed divided character image data memory 2707. The prediction method here is the same as the prediction method in step S2803, and may be any method that is consistent with the encoding method in step S1306. What has already been described with respect to the limit code amount and its prediction is also applicable.

  Next, the capacity predicting unit 2708 predicts the capacity after encoding of the first character image data obtained in step S2803 and the capacity after encoding of the second processed divided character image data obtained in step S2806. If the latter is larger (YES in step S2807), the second processed divided character image data stored in the second processed divided character image data memory 2707, that is, image data after rotation is output. (Step S2808), otherwise (NO in Step S2807), the first processed divided character image data stored in the first processed divided character image data memory 2705, that is, the image data before rotation is output (Step S2809). ).

  Next, the image calculation unit 2701 stores the determination result in step S2807, that is, a flag indicating which processing in step S2808 or step S2809 has been executed in the flag data memory 2410 (step S2810). The value of the flag can be, for example, “1” indicating that the predicted capacity value of the first character image data obtained in step S2803 is large, and “0” indicating otherwise. . In step S2810, a flag value is determined for each character. In the flag data memory 2708, a flag for each character is stored in association with the access table data stored in the access table data memory 2407 and the encoded data stored in the encoding table data memory 2405. . Specifically, the flag, the access table data, and the encoded data are also associated with each other in the order of processing.

  When the above-described processing is executed by the image encoding device according to the present embodiment, the character encoding data is mainly composed of vertical lines or mainly composed of horizontal lines. By using this feature, highly efficient encoding can be performed with a small amount of calculation. That is, even if the character image data to be encoded is directly calculated as the character image data shown in FIG. 27, the frequency of the value of a specific word is obtained as shown in FIG. In the case of character image data that does not have the effect of increasing, the exclusive OR is calculated by rotating 90 degrees as shown in FIG. As a result, the output data is as shown in FIG. 36, and the frequency of bytes having a value of zero can be increased. For this reason, when entropy encoding is performed, encoding can be performed after concentrating the value distribution on a specific value without losing the information of the original image data (without losing reversibility), and encoding efficiency. It contributes to the improvement.

<2. Image decoding device>
[Third Embodiment]
FIG. 1 is a diagram illustrating a specific example of the hardware configuration of a mobile phone 1 as a text processing device equipped with the image decoding device according to the present embodiment, and a specific example of the hardware configuration of a general mobile phone. FIG.

  Referring to FIG. 1, a mobile phone 1 includes an input / output unit 140 that is an interface with a user, a CPU (Central Processing Unit), and the like, a control unit 120 that controls the entire device, and other devices. A communication unit 110 for communicating with a computer, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, received from a program executed by the control unit 120, intermediate data of the program, and other computers And a storage unit 130 for storing the data and the like.

  The communication unit 110 performs communication via a base station (not shown) and transmits / receives data to / from other devices such as a mobile phone.

  Further, the input / output unit 140 described above displays a key code input device (key) 142 including numeric buttons such as “1” and “2” and direction buttons such as “R” and “L”, and information to the user. A display 144 such as an LCD (Liquid Crystal Display), a microphone 146 that inputs sound, a speaker 148 that outputs sound, and a camera 149 that captures and inputs an image.

  The image decoding apparatus according to the present embodiment is configured by hardware of the mobile phone 1 and software stored in the storage unit 130 and executed by the control unit 120, and a function for performing an image decoding process to be described later is controlled. The unit 120 is mainly formed in the control unit 120 by reading and executing the program stored in the storage unit 130. Alternatively, at least a part of the above functions may be configured by the hardware of the mobile phone 1. The normal operation of the mobile phone 1 shown in FIG. 1 as a mobile phone is well known.

  FIG. 37 is a schematic diagram of a hardware configuration of a text processing apparatus in which the image decoding apparatus according to the present embodiment is mounted. The cellular phone 1 in which the image decoding apparatus according to the present embodiment shown in FIG. 2 is a block diagram schematically illustrating a hardware configuration. FIG.

  Referring to FIG. 37, the text processing apparatus includes an instruction device 4600 corresponding to the input / output unit 140, a controller 4601 corresponding to the control unit 120 and the like, a text data memory 4602 corresponding to a predetermined area of the storage unit 130, and an image decoding device. 4603, a display device 4604 corresponding to the display 144, and a storage device 4606 corresponding to the storage unit 130, and each element is connected by a data bus 4605.

  Text data is stored in the text data memory 4602 as character identification information of each character. Here, it is assumed that the character identification information includes a character code and typeface identification information, as in the first embodiment. Normally, the typeface is not changed frequently, so when using the same typeface as the previous character in the text data, the typeface identification information is omitted and the typeface is changed from the previous character. Only typeface identification information may be added.

  The storage device 4605 stores a program executed by the controller 4601 and other data. The text data memory 4602 may be configured on the storage device 4605.

  When the controller 4601 receives an instruction from the instruction device 4600, the controller 4601 reads out and executes the program stored in the storage device 4605, and controls the image decoding device 4603 to execute the decoding process. The image decoding device 4603 executes a process of decoding the corresponding glyph each time character identification information is given from the controller 4601 in response to an instruction signal from the instruction device 4600. That is, the image decoding apparatus according to the present embodiment is configured by hardware of a text processing apparatus and software stored in the storage device 4606 and executed by the controller 4601. Further, a function for performing an image decoding process to be described later is formed by the controller 4601 reading and executing a program stored in the storage device 4606. Or at least one part of the said function may be comprised by the hardware of a text processing apparatus.

  FIG. 38 is a flowchart showing image decoding processing in the text processing apparatus according to this embodiment. The processing shown in the flowchart of FIG. 38 is realized by the controller 4601 reading out and executing a program stored in the storage device 4606 and controlling each unit shown in FIG.

  Referring to FIG. 38, first, controller 4601 reads character identification information for one character from text data memory 4602 in accordance with an instruction signal from instruction device 4600 (step S4701). The image decoding device 4603 decodes the glyph corresponding to the character identification information read in step S4701 (step S4702). If the decoding is successful (YES in step S4703), the process proceeds to step S4704, and if not (NO in step S4703), the process proceeds to step S4705.

  In step S4704, the controller 4601 outputs the glyph decoded in step S4702 to the display device 4604 and generates a display signal for display (step S4704).

  If all characters in text data memory 4602 have been processed (YES in step S4705), the process ends; otherwise, the process returns to step S4701.

  FIG. 39 is a block diagram illustrating a specific example of a functional configuration that functions as the image decoding device 4603 in the mobile phone 1 that is the text processing device according to the present embodiment and performs the image decoding processing in step S4702. The image decoding apparatus according to the present embodiment accesses character font data that is encoded data encoded by the image encoding apparatus according to the first embodiment, and decodes necessary font data.

  Referring to FIG. 39, the above functions of the image decoding apparatus are as follows: controller 3301, encoded data memory 3302, entropy code decoding unit 3303, processed divided character image data memory 3304, access table data conversion unit 3305, access table data memory 3306. The image processing unit 3307 and the character image data memory 3308 are included, and the respective components are connected to each other and to the outside via the data bus 3309.

  FIG. 40 is a block diagram illustrating a specific example of the configuration of the image processing unit 3307. Referring to FIG. 40, image processing unit 3307 includes an image calculation unit 4801, a character image data memory 4802, and a divided character image data memory 4803. Each component is connected to each other via a data bus 4804, or Connected externally.

  FIG. 41 is a block diagram showing a specific example of the configuration of the access table data conversion unit 3305. Referring to FIG. 41, access table data conversion unit 3305 includes character identification information / glyph number conversion unit 5101 and glyph number / offset information conversion unit 5102, and each component is connected via data bus 5103. Connected to each other and to the outside.

  The encoded data memory 3302 and the access table data memory 3306 are configured by a predetermined area of the storage device 4604, and are respectively encoded data generated by the image encoding device according to the first embodiment and the access table. Store the data.

  The character identification information / glyph number conversion unit 5101 of the access table data conversion unit 3305 acquires an internal character code based on the character identification information received from the controller 3301. As the acquisition method here, the same method as the acquisition method in the first embodiment may be used. The character identification information / glyph number conversion unit 5101 refers to the access table data stored in the access table data memory 3306, identifies the glyph number corresponding to the internal character code, and converts the character identification information into the glyph number. To do. The converted glyph number is further converted into offset information by the glyph number / offset information converting unit 5102 of the access table data converting unit 3305 and input to the entropy code decoding unit 3303.

  The entropy code decoding unit 3303 uses offset information, which is input from the access table data conversion unit 3305 and is information for specifying a position on the encoded data, on the encoded data stored in the encoded data memory 3302. The part corresponding to the divided character image data corresponding to the character identification information to be decoded is accessed. Then, the encoded data of that portion (that is, data at the position specified by the offset information) is decoded and stored in the processed divided character image data memory 3304 as “processed divided character image data”. The processed divided character image data memory 3304 is also configured by a predetermined area of the storage device 4604 and stores the decoded data.

  The image calculation unit 4801 of the image processing unit 3307 calculates an exclusive OR of one piece of the processed divided character image data stored in the processed divided character image data memory 3304, and obtains “divided character image data”. The divided character image data memory 4803 is stored. The divided character image data memory 4803 is also configured by a predetermined area of the storage device 4604 and stores the divided character image data.

  Here, similarly to the calculation of the difference in the first embodiment, the 0th line extracted from the processed divided character image data that is the input data is used as it is as the 0th line of the divided character image data that is the output data. For the first and subsequent lines, the exclusive OR of the nth line of the processed divided character image data, which is the input data, and the (n-1) th line of the already restored divided character image data is output data. Is the value of the nth line of the divided character image data. By sequentially performing this process, the image processing unit 3307 restores the divided character image data from the processed divided character image data.

The reason why the divided character image data can be restored by this processing is that the operation of taking the exclusive OR is the inverse transformation of itself. That is,
C = A ^ B
If B = A ^ C
This is because

Therefore, for n ≧ 1, shown in the first embodiment,
(Nth line of processed divided character image data) = ((n-1) th line of divided character image data) ^ (nth line of divided character image data)
From the relationship
(Nth line of divided character image data) = ((n-1) th line of divided character image data) ^ (nth line of processed divided character image data)
Holds. That is, the value of the nth line of the divided character image data can be calculated using the value of the (n−1) th line of the divided character image data and the value of the nth line of the processed divided character image data.

As for n = 0, as also shown in the first embodiment,
(Nth line of processed divided character image data) = (nth line of divided character image data)
Therefore, it can be restored by copying the 0th line of the processed divided character image data directly to the divided character image data.

  Of course, if the processing on the encoding side is not exclusive OR between adjacent lines, if the transformation does not lose the information of the original image data (does not lose reversibility), decoding corresponding to this is possible. The divided character image data can be obtained from the processed divided character image data by performing the above process.

  The divided character image data stored in the divided character image data memory 4802 is integrated in the image calculation unit 4801 of the image processing unit 3307 to generate original character image data. The generated character image data is stored in the character image data memory 4802. The character image data stored in the character image data memory 4802 is stored in the character image data memory 3308 by the image calculation unit 4801. The character image data memories 4802 and 3308 are also configured by a predetermined area of the storage device 4604, and store character image data obtained as a result of the decoding process.

  FIG. 42 is a flowchart showing the decoding process executed by the image decoding apparatus in step S4702. Note that a device that uses the image decoding device, such as a text processing device equipped with the image decoding device, is referred to as a “main body module” in the following description.

  Referring to FIG. 42, first, controller 3301 of the image decoding apparatus receives character identification information from controller 4601 of the text processing apparatus (step S3401). The character identification information acquired in step S3401 is converted into a glyph number by the access table data conversion unit 3305 (step S3402).

  If the character identification information is successfully converted in step S3402 (YES in step S3403), the process proceeds to step S3405. If not (NO in step S3403), the process proceeds to step S3404. In step S3404, the controller 3301 returns an error value notifying the main body module that the decoding has not been successful (step 3404). If an error value is returned, the main module may perform appropriate processing such as displaying a space instead of the requested glyph and displaying an alternative character.

  In step S3405, the glyph number converted in step S3402 is converted into offset information by the access table conversion unit 3305 (step S3405).

  Next, the entropy code decoding unit 3303 corresponds to the character identification information acquired in step S3401 on the encoded data stored in the encoded data memory 3302 using the offset information converted in step S3405. The part corresponding to the processed divided character image data is accessed, and the encoded data of that part is decoded (step S3406). Then, the processed divided character image data obtained by decoding is stored in the processed divided character image data memory 3304.

  When the processing for all the processed divided character image data corresponding to the character identification information acquired in step S3401 is completed (YES in step S3407), the process proceeds to step S3408; otherwise (NO in step S3407), The process returns to step S3405.

  In step S3408, the image processing unit 3307 calculates an exclusive OR of the processed divided character image data decoded in step S3406 to obtain divided character image data. Next, the image processing unit 3308 integrates the divided character image data obtained in step S3408 to create original character image data (step S3409). The created character image data is stored in the character image data memory 3308, and the process ends.

  FIG. 43 is a flowchart showing the conversion process to the glyph number in step S3402. As in the first embodiment, the access table data stored in the access data memory 3306 includes character identification information / glyph number conversion data 1401, glyph number / offset, as shown in FIG. Further, the character identification information / glyph number conversion data 1401 includes a status table 1501, a first auxiliary table 1502, and a second auxiliary table 1503, as shown in FIG. In the following description, it is assumed that the access table data shown in FIGS. 8 and 19 is stored in the access data memory 3306 of the image decoding apparatus.

  Referring to FIG. 43, first, the character identification information / glyph number conversion unit 5101 acquires an internal character code for the target character based on the character identification information acquired in step S3401 (step S5201). This acquisition method is the same as the acquisition method (step S2301) in the first embodiment.

  Next, the character identification information / glyph number conversion unit 5101 accesses the status table 1501 stored in the access data memory 3306 (step S5202), and the internal character code acquired in step S5201 is defined in the status table 1501. Read the value. If the value specified in status table 1501 is “0” (YES in step S5203), the process proceeds to step S5205. If the value specified in status table 1501 is “2” (NO in step S5203, and If YES in step S5204, the process advances to step S5207; otherwise, if the specified value is “1” (NO in step S5203 and NO in step S5204), the process advances to step S5206.

  In step S5205, that is, if the value defined in the status table 1501 corresponding to the internal character code acquired in step S5201 is “0”, it is defined that there is no glyph corresponding to the internal character code. Therefore, the character identification information / glyph number conversion unit 5101 returns an error, and the process proceeds to step S3403.

  For an internal character code in which “1” or “2” is defined in the status table, it is necessary to obtain the corresponding glyph number.

  For the internal character code for which “1” is defined in the status table, the number of internal character codes for which “1” is defined in the past decoding processes is checked, and the obtained result is used as the glyph number. To do. As shown in FIG. 23, since the glyph numbers corresponding to some of the internal character codes are described in the first auxiliary table 1502, such access can be speeded up.

  In step S5206, that is, if the value defined in the status table 1501 corresponding to the internal character code acquired in step S5201 is “1”, the character identification information / glyph number conversion unit 5101 performs the first auxiliary table. The glyph number corresponding to the internal character code acquired in step S5201 is specified from 1502 and the status table 1501, and the process proceeds to step S3403. As a specific method for specifying the glyph number, the character identification information / glyph number conversion unit 5101 extracts the nearest internal character code that is not larger than the internal character code from the first auxiliary table 1502 and extracts it. Specifies the glyph number corresponding to the internal character code. Then, the number of internal character codes defined as “1” in the status table 1501 is counted from the extracted internal character code to the internal character code acquired in step S5201, and the internal character code acquired in step S5201 is counted. Glyph number.

  Specifically, the internal character code acquired in step S5201 is “11” in which the glyph number corresponding to the internal character code “11” is described as “8” in the status table of FIG. To do. In step S5206, the character identification information / glyph number conversion unit 5101 first extracts “10” from the first auxiliary table 1502 of FIG. 23 as a value closest to “11” without exceeding “11”. The glyph number “7” corresponding to the internal character code “10” is specified. This gives you an estimate of the glyph number. Then, by referring to the status table of FIG. 22, by counting the number of internal character codes “8” defined as “1” in the status table 1501 from the 10th to the next internal character code, A glyph number “8” corresponding to the internal character code “11” is obtained. This matches the glyph number “8” obtained from the status table 1501 of FIG.

  In step S5207, that is, if the value defined in the status table 1501 corresponding to the internal character code acquired in step S5201 is "2", the character identification information / glyph number conversion unit 5101 Referring to auxiliary table 5303, the glyph number corresponding to the internal character code is specified, and the process proceeds to step S3403.

  The character identification information / glyph number conversion data used in the character identification information / glyph number conversion unit 5101 is one specific example, and the conversion data generated here is the character identification information / glyph as described above. It is not limited to number conversion data. The point here is whether the correspondence between the character identification information (or the internal character code uniquely determined therefrom) and the glyph number or glyph is one-to-one or not (or how many glyph numbers or glyphs are Data indicating the number of glyph numbers or the number of glyphs corresponding to the character identification information, or conversely, the character identification information (or internal character code) and the glyph number at a high speed. Alternatively, it is necessary for the character identification information / glyph number conversion data by determining whether or not the correspondence relationship with the glyph is one-to-one and referring to a different table according to the determination result. Character identification information (or internal character code) can be converted to glyph numbers at high speed (specifying glyph data) while keeping the data capacity small. It lies in the fact that you kill so. Specifically, in this embodiment, whether or not the character identification information has a one-to-one correspondence with the glyph is determined by accessing the status table 1501, and if the character identification information has a one-to-one correspondence, the first auxiliary table. 1502 is referred to, and if not, the second auxiliary table 1503 is referred to. Further, the first auxiliary table 1502 is a subset of a correspondence table of character identification information (or internal character code) and glyph numbers, and the image decoding apparatus accesses the first auxiliary table 1502 to access the glyph number. By using this approximate value, a true glyph number can be obtained by accessing the status table 1501 a smaller number of times compared to when the first auxiliary table 1502 is not used. It has become.

  FIG. 44 is a flowchart showing the exclusive OR calculation processing in step S3408.

  Referring to FIG. 44, first, image calculation unit 4801 calculates an exclusive OR for one piece of processed divided character image data stored in processed divided character image data memory 3304 in step S3406, and performs division. Character image data is stored in the divided character image data memory 4803 (step S4901). As described above, the process of calculating the exclusive OR of the encoded data corresponds to the reverse process of the process of calculating the exclusive OR at the time of data encoding. The divided character image data before encoding is restored.

  When the process of calculating the exclusive OR for all the processed divided character image data corresponding to the character identification information acquired in step S3401 is completed (YES in step S4902), the process proceeds to step S3409. Otherwise (NO in step S4902), the process returns to step S4901.

  FIG. 45 is a flowchart showing the integration processing of divided character image data in step S3409.

  Referring to FIG. 45, first, image calculation unit 4801 integrates the divided character image data stored in divided character image data memory 4802 as a result of the execution of the process of step S3408 to obtain character image data. The data is stored in the memory 4802 (step S5001). The image calculation unit 4801 reads the character image data stored in the character image data memory 4802, outputs it to the character image data memory 3308, and stores it in the character image data memory 3308 (step S5002). Thus, the process ends.

[Fourth Embodiment]
The image decoding apparatus according to the fourth embodiment is an apparatus that decodes the encoded data encoded by the image encoding apparatus according to the second embodiment.

  FIG. 46 is a block diagram showing a specific example of a functional configuration for functioning as an image decoding device and performing image decoding processing in the text processing device according to the present embodiment.

  Referring to FIG. 46, the function of the image decoding apparatus according to the present embodiment includes, in addition to the functions included in the function of the image decoding apparatus according to the third embodiment shown in FIG. A flag data memory 3610 is included.

  The flag data memory 3610 includes a predetermined area of the storage device 4604, and stores in advance flag data generated by the image encoding device according to the second embodiment.

  The decoding process in the image decoding apparatus according to the third embodiment is the same as the decoding process shown in FIG. 42 in the second embodiment.

  FIG. 47 is a flowchart showing the division character image data integration processing in step S3409 according to the present embodiment.

  Referring to FIG. 47, the image calculation unit 4801 of the image processing unit 3307 according to the present embodiment integrates the divided character image data stored in the divided character image data memory 4803 and stores the divided character image data in the character image data memory 4802. Store (step S5401).

  The image calculation unit 4801 refers to the flag value corresponding to the character image data to be processed in step S5401 among the flag data stored in the flag data memory 3610 (step S5402). If the flag value is “0”, that is, if the rotated image data has been encoded (NO in step S5402), the process proceeds to step S5403, and if the flag value is “1”. That is, if the image data before rotation has been encoded (YES in step S5402), step S5403 is skipped, and the process proceeds to step S5404.

  In step S5403, the image calculation unit 4801 rotates the character image data stored in the character image data memory 3502 by 90 degrees, and then stores it again in the character image data memory 3502 (step S5403). In step S5403, image calculation unit 4801 rotates the character image data in the opposite direction to the rotation (step S3703) performed by image calculation unit 2701 on the first character image data in the second embodiment. Shall. Accordingly, in correspondence with the fact that the character image data is rotated 90 degrees clockwise in the image encoding apparatus according to the second embodiment, here, it is rotated 90 degrees in the opposite direction, that is, counterclockwise (“clock” It may also be expressed as “-90 degrees around”). In other words, when generalized, the process executed here is a process of performing an inverse transformation so as to cancel the influence of the transformation (here, the rotation process) performed on the character image data at the time of encoding.

  The image calculation unit 4801 reads the character image data stored in the character image data memory 4802 in step S5401 or step S5403, outputs the character image data to the character image data memory 3308, and stores it in the character image data memory 3308 (step S5404). . Thus, the process ends.

  Furthermore, it is possible to provide a program that causes a computer to execute the above-described image encoding process and / or image decoding process. Such a program can be recorded on a computer-readable recording medium such as a flexible disk, a CD-ROM, a ROM, a RAM, and a memory card attached to the computer and provided as a program product. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built in the computer. A program can also be provided by downloading via a network.

  The program according to the present invention is a program module that is provided as a part of a computer operating system (OS) and calls necessary modules in a predetermined arrangement at a predetermined timing to execute processing. Also good. In that case, the program itself does not include the module, and the process is executed in cooperation with the OS. A program that does not include such a module can also be included in the program according to the present invention.

  The program according to the present invention may be provided by being incorporated in a part of another program. Even in this case, the program itself does not include the module included in the other program, and the process is executed in cooperation with the other program. Such a program incorporated in another program can also be included in the program according to the present invention.

  The provided program product is installed in a program storage unit such as a hard disk and executed. The program product includes the program itself and a recording medium on which the program is recorded.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

2 is a diagram illustrating a specific example of a hardware configuration of a mobile phone 1. FIG. It is a block diagram which shows the specific example of a function structure of the image coding apparatus concerning 1st Embodiment. FIG. 11 is a block diagram illustrating a specific example of a configuration of an image processing unit 1209. 5 is a block diagram showing a specific example of the configuration of an access table data generation unit 1206. FIG. It is a figure showing the specific example of character image data. 5 is a diagram illustrating a specific example of image data stored in an image data memory 1202. FIG. It is a figure showing the specific example of a character identification information and a glyph number correspondence rule. It is a figure showing the specific example of access table data. It is a flowchart which shows the encoding process concerning 1st Embodiment. It is a flowchart which shows the division process of the image data in step S1303. It is a figure showing the specific example of character image data. It is a figure showing the specific example of division | segmentation character image data. It is a figure showing the specific example of division | segmentation character image data. It is a figure showing the specific example of character image data. It is a figure explaining arrangement | positioning of character image data. It is a flowchart which shows the calculation process of exclusive OR in step S1304. It is a figure showing the specific example of process division | segmentation character image data. It is a flowchart which shows the production | generation process of the access table in step S1308. It is a figure showing the specific example of character identification information and glyph number conversion data. It is a figure showing the specific example of a response | compatibility with a character code and an internal character code. It is a figure explaining the technique converted into an internal character code from a character code and typeface identification information. It is a figure showing the specific example of a status table. It is a figure showing the specific example of a 1st auxiliary table. It is a figure showing the specific example of a status table. It is a figure showing the specific example of a 2nd auxiliary table. It is a figure explaining the characteristic of character image data. It is a figure explaining the characteristic of character image data. It is a figure explaining the calculation result of the exclusive OR of character image data. It is a figure explaining the calculation result of the exclusive OR of character image data. It is a block diagram which shows the specific example of a function structure of the image coding apparatus concerning 2nd Embodiment. FIG. 11 is a block diagram illustrating a specific example of a configuration of an image processing unit 1209. It is a flowchart which shows the encoding process concerning 2nd Embodiment. 16 is a flowchart illustrating image data division processing in step S2503. It is a flowchart which shows the calculation process of exclusive OR in step S2504. It is a figure explaining rotation operation. It is a figure explaining the calculation result of the exclusive OR of character image data. It is the schematic of the hardware constitutions of a text processing apparatus. It is a flowchart which shows the image decoding process in a text processing apparatus. It is a block diagram which shows the specific example of a function structure of the image decoding apparatus concerning 3rd Embodiment. FIG. 20 is a block diagram illustrating a specific example of a configuration of an image processing unit 3307. 5 is a block diagram illustrating a specific example of a configuration of an access table data conversion unit 3305. FIG. It is a flowchart which shows the decoding process performed with an image decoding apparatus in step S4702. It is a flowchart which shows the conversion process to a glyph number in step S3402. It is a flowchart which shows the calculation process of exclusive OR in step S3408. It is a flowchart which shows the integration process of the division | segmentation character image data in step S3409 in 3rd Embodiment. It is a block diagram which shows the specific example of a function structure of the image decoding apparatus concerning 4th Embodiment. It is a flowchart which shows the integration process of the division | segmentation character image data in step S3409 in 4th Embodiment. It is a figure which shows the specific example of the hardware constitutions of PC3. It is a figure explaining addition of process division | segmentation character image data. It is a figure explaining addition of process division | segmentation character image data. It is a figure explaining addition of process division | segmentation character image data. It is a figure explaining addition of process division | segmentation character image data.

Explanation of symbols

  1 mobile phone, 2 recording medium, 3 PC, 101 CPU, 103 ROM, 105 RAM, 107 hard disk drive, 109 reading unit, 110 communication unit, 111 input unit, 113 communication unit, 115 display unit, 120 control unit, 130 storage , 140 input / output unit, 142 key code input device, 144 display, 146 microphone, 148 speaker, 149 camera, 1201 controller, 1202 image data memory, 1203 processed divided image data memory, 1204 entropy encoding unit, 1205 encoded data Memory, 1206 access table data generation unit, 1207 access table data memory, 1208 character identification information / glyph number correspondence rule memory, 1209 image processing unit, 1210 data bus, 201 Character identification information / glyph number conversion data generation unit 2202 Glyph number / offset information conversion data generation unit 2203 Data bus 2410 Flag data memory 2701 Image operation unit 2702 First character image data memory 2703 Second character image Data memory, 2704 first divided character image data memory, 2705 second divided character image data memory, 2706 first processed divided character image data memory, 2707 second processed divided character image data memory, 2708 capacity prediction unit, 2709 data bus, 3301 Controller, 3302 Encoded data memory, 3303 Entropy code decoding unit, 3304 Processed divided character image data memory, 3305 Access table data conversion unit, 3306 Access table data memory, 3307 Image processing unit, 3308 character image data memory, 3309 data bus, 3610 flag data memory, 3801 image operation unit, 3802 character image data memory, 3803 divided character image data memory, 3804 modified divided character image data memory, 3805 data bus, 4600 Pointing device, 4601 controller, 4602 text data memory, 4603 image decoding device, 4604 display device, 4606 storage device, 4605 data bus, 4801 image operation unit, 4802 character image data memory, 4803 divided character image data memory, 5101 character identification information Glyph number conversion unit, 5102 Glyph number / offset information conversion unit, 5103 Data bus.

Claims (17)

An image encoding device for encoding character image data specified by character identification information included in image data,
And reading reading means the character image data of one character minute from the image data,
The character image data for one character is divided in a second direction orthogonal to the first direction at a processing unit size that is a fraction of an integer of the size in the first direction , and divided unit image data Image segmentation means for generating
Dots between the value of the nth line parallel to the first direction and the value of the (n−1) th line adjacent to the nth line in the second direction , included in the divided unit image data A difference for each position is calculated by a predetermined method, and for each line of n ≧ 1, the difference is set as the value of the nth line, and for the 0th line (n = 0 line), the difference of the divided unit image data. Processing division unit image data creating means for generating processing division unit image data using the value of 0 line as it is;
An image code comprising: encoding means for encoding the processed divided unit image data obtained from the character image data for each character and continuously encoding the plurality of the character image data to generate encoded data Device. The apparatus according to claim 1, further comprising: an access table generating unit that generates an access table indicating correspondence between information specifying the character image data for one character and a position corresponding to the character image data on the encoded data. The image encoding device described. The image encoding apparatus according to claim 1 , wherein the character identification information includes a character code or a character code and typeface identification information. An acquisition means for acquiring a correspondence between the character identification information and the glyph;
The access table generating means includes
Means for obtaining an internal character code from the character identification information of the character image data;
Means for identifying the glyph corresponding to the internal character code from the correspondence between the acquired internal character code and the acquired character identification information and the glyph;
By searching the encoded data and extracting the boundary position corresponding to each of the processed divided unit image data, the glyph and the character identification information corresponding to the glyph on the encoded data are represented by the character identification information. Means for generating a correspondence with the position of the character image data;
The image encoding apparatus according to claim 1 , further comprising: a unit that specifies a position corresponding to the character image data on the encoded data by referring to the correspondence relationship from the specified glyph. Calculating means for calculating the encoded data amount of the first processed divided unit image data obtained from the first divided unit image data obtained from the character image data;
Rotating means for rotating the character image data by 90 degrees to generate rotated image data;
Regarding the second divided unit image data obtained by dividing the rotated image data in the first direction, the value of the nth line and the (n−1) th line included in the second divided unit image data. A prediction means for calculating a data amount after the encoding of the second processed divided unit image data using the difference as a value of the n-th line.
The encoding means encodes the processed divided unit image data having a smaller data amount after the encoding among the first processed divided unit image data and the second processed divided unit image data. 2. The image encoding device according to 1. The said encoding means is further provided with a means to produce | generate the information which shows which process division unit image data of the said 1st process division unit image data and the said 2nd process division unit image data were encoded. 5. The image encoding device according to 5. An image decoding device for executing a decoding process on the encoded data generated by the image encoding device according to claim 1 to obtain character image data for one character,
Obtaining means for obtaining information specifying the character image data for one character ;
The code corresponding to the information specifying the character image data obtained by accessing the access table indicating the correspondence between the information specifying the character image data and the position corresponding to the character image data on the encoded data Specifying means for specifying the position on the data,
A plurality of processing division units are decoded by decoding data at the specified position on the encoded data , which is generated by continuously encoding a plurality of character image data by the image encoding device. Decoding means for generating image data;
The value of the nth line of each of the divided unit image data using the value of the (n−1) th line of each of the divided unit image data and the value of the nth line of each of the processed divided unit image data. Generating means for generating divided unit image data from each of the plurality of processed divided unit image data;
An image decoding apparatus comprising: an integration unit that integrates a plurality of the division unit image data created from the plurality of processed division unit image data by the creation unit to generate character image data for one character . If the character image data to access the information indicating whether or not that is rotated 90 degrees at the time of encoding, the character image data were rotated 90 degrees at the time of coding, the said character image data The image decoding apparatus according to claim 7 , further comprising means for rotating 90 degrees in the opposite direction to the direction of rotation at the time of encoding. A mobile phone equipped with the image decoding device according to claim 7 or 8 . In the image coding apparatus, it included in the image data, character image data specified by the character identification information A method of encoding,
A reading step of reading character image data for each character from the image data;
The character image data for one character is divided in a second direction orthogonal to the first direction at a processing unit size that is a fraction of an integer of the size in the first direction , and divided unit image data An image segmentation step for generating
Dots between the value of the nth line parallel to the first direction and the value of the (n−1) th line adjacent to the nth line in the second direction , included in the divided unit image data A difference for each position is calculated by a predetermined method, and for each line of n ≧ 1, the difference is set as the value of the nth line, and for the 0th line (n = 0 line), the difference of the divided unit image data. A processing division unit image data creation step for generating processing division unit image data using the value of 0 line as it is,
An encoding step of encoding the processed division unit image data obtained from the character image data for each character and continuously encoding the plurality of the character image data to generate encoded data. Method. A calculation step of calculating the encoded data amount of the first processed divided unit image data obtained from the first divided unit image data obtained from the character image data;
A rotation step of rotating the character image data by 90 degrees to generate rotated image data;
Regarding the second divided unit image data obtained by dividing the rotated image in the first direction, the value of the nth line and the value of the (n−1) th line included in the second divided unit image data. A prediction step of predicting the encoded data amount of the second processed division unit image data using the difference as the value of the n-th line,
In the encoding step, of the first processed division unit image data and the second processed division unit image data, the processed divided unit image data having a smaller data amount after the encoding is encoded. Item 15. The image encoding method according to Item 10 . A character image for one character by performing a decoding process on the encoded data generated by continuously encoding a plurality of character image data by the image encoding method according to claim 11 or 12. A method of obtaining data ,
An acquisition step of acquiring information specifying the character image data for one character ;
The code corresponding to the information specifying the character image data obtained by accessing the access table indicating the correspondence between the information specifying the character image data and the position corresponding to the character image data on the encoded data A specific step of identifying a position on the data,
By decoding the data at the specified position on the encoded data generated by sequentially encoding a plurality of character image data by the image encoding method , a plurality of processed division unit images A decryption step for generating data;
The value of the nth line of each of the divided unit image data using the value of the (n−1) th line of each of the divided unit image data and the value of the nth line of each of the processed divided unit image data. And a creation step of generating divided unit image data from each of the plurality of processed divided unit image data,
An image decoding method comprising: an integration step of generating character image data for one character by integrating the plurality of division unit image data generated from the plurality of processed division unit image data in the generation step. If the character image data to access the information indicating whether or not that is rotated 90 degrees at the time of encoding, the character image data were rotated 90 degrees at the time of coding, the said character image data The image decoding method according to claim 12 , further comprising a step of rotating 90 degrees in the opposite direction to the direction of rotation at the time of encoding. A program for causing a computer to execute processing for encoding character image data specified by character identification information included in image data,
A reading step of reading character image data for each character from the image data;
The character image data for one character is divided in a second direction orthogonal to the first direction at a processing unit size that is a fraction of an integer of the size in the first direction , and divided unit image data An image segmentation step for generating
Dots between the value of the nth line parallel to the first direction and the value of the (n−1) th line adjacent to the nth line in the second direction , included in the divided unit image data A difference for each position is calculated by a predetermined method, and for each line of n ≧ 1, the difference is set as the value of the nth line, and for the 0th line (n = 0 line), the difference of the divided unit image data. A processed image creation step for generating processed division unit image data using the value of 0 line as it is;
An encoding step of encoding the processed division unit image data obtained from the character image data for each character and continuously encoding the plurality of the character image data to generate encoded data; Encoding program. A calculation step of calculating the encoded data amount of the first processed divided unit image data obtained from the first divided unit image data obtained from the character image data;
A rotation step of rotating the character image data by 90 degrees to generate rotated image data;
Regarding the second divided unit image data obtained by dividing the rotated image data in the first direction, the value of the nth line and the (n−1) th line included in the second divided unit image data. A prediction step of calculating a data amount after the encoding of the second processed divided unit image data using the difference as the value of the nth line,
In the encoding step, of the first processed division unit image data and the second processed division unit image data, the processed divided unit image data having a smaller data amount after the encoding is encoded. Item 15. The image encoding program according to Item 14 . One character is obtained by executing a decoding process on encoded data generated by continuously encoding a plurality of character image data by executing the image encoding program according to claim 15 or 16. A program for causing a computer to execute processing for obtaining character image data of minutes ,
An acquisition step of acquiring information specifying the character image data for one character ;
The code corresponding to the information specifying the character image data obtained by accessing the access table indicating the correspondence between the information specifying the character image data and the position corresponding to the character image data on the encoded data A specific step of identifying a position on the data,
By decoding the data at the specified position on the encoded data generated by sequentially encoding a plurality of character image data by executing the image encoding program , A decoding step for generating processing division unit image data;
The value of the nth line of each of the divided unit image data using the value of the (n−1) th line of each of the divided unit image data and the value of the nth line of each of the processed divided unit image data. And a creation step of generating divided unit image data from each of the plurality of processed divided unit image data,
An image decoding program that executes an integration step of generating a character image data for one character by integrating a plurality of the division unit image data generated from the plurality of processed division unit image data in the generation step. If the character image data to access the information indicating whether or not that is rotated 90 degrees at the time of encoding, the character image data were rotated 90 degrees at the time of coding, the said character image data The image decoding program according to claim 16 , further comprising a step of rotating 90 degrees in the opposite direction to the direction of rotation at the time of encoding.

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