JP2012004667A - Image processing device, image processing method, and image processing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the shapes of characters otherwise lost when image data is reduced, and to minimize a data quantity.SOLUTION: An MFP comprises: an image data acquisition unit (S01) for acquiring image data; a character area extraction unit (S03) for extracting from the acquired image data a character area in which characters are expressed: a vector section conversion unit (S05) for converting, to vector data, a specific line except for a line segment inclined within a predetermined zone in the extracted character area; a reduction unit (S08) for converting the image data to reduced image data having low resolution; and an output unit (S09) for outputting a set of the reduced image data and vector data.

Description

  The present invention relates to an image processing apparatus, an image processing method, and an image processing program, and more particularly to an image processing apparatus suitable for compression or expansion of an image including characters, an image processing method and an image processing program executed by the image processing apparatus.

  Since part of the character shape is lost by reducing the image of the character, when the reduced image is enlarged, a jagged noise called so-called jaggy is generated in the specific line portion. For this reason, a technique for expressing characters in an image as a vector is known. For example, in Japanese Patent Laid-Open No. 11-85129, a basic character component (stroke body) and a local outline (stroke head, tail) of a plurality of characters are stored in a vector format and combined to form a stroke. A character generator that generates a desired character pattern by arranging the strokes according to stroke synthesis information is described.

However, according to the conventional character generator, since all the characters in the image are represented by vector-type strokes, there is a problem that the amount of data may increase.
JP-A-11-85129

  The present invention has been made to solve the above-described problems, and one of the objects of the present invention is to maintain the shape of characters lost when image data is reduced, and to reduce the amount of data as much as possible. An image processing apparatus, an image processing system, an image processing method, and an image processing program are provided.

  Another object of the present invention is to provide an image processing device, an image processing system, an image processing method, and an image processing program capable of reducing noise generated in the outline of characters in image data.

  The present invention has been made to solve the above-described problems. According to one aspect of the present invention, an image processing apparatus includes an image data acquisition unit that acquires image data, and characters are represented from the acquired image data. A character area extracting means for extracting the extracted character area, a vector partial converting means for converting a specific line excluding a line segment having a slope within a predetermined range in the extracted character area into vector data, and image data, Reduction means for converting to reduced image data having a resolution lower than the resolution of the image data; and output means for outputting a set of reduced image data and vector data.

  According to this aspect, the specific line of the image data is converted into vector data, the image data is converted into reduced image data with a low resolution, and a set of reduced image data and vector data is output. For this reason, the shape of the character lost by reducing image data can be included in vector data. Further, since all lines of characters are not converted to vector data, the amount of vector data can be reduced as much as possible. As a result, it is possible to provide an image processing apparatus capable of retaining the character shape lost when the image data is reduced and reducing the data amount as much as possible.

  Preferably, an erasing unit that erases a specific line in the character region extracted from the image data or the reduced image data is further provided.

  According to this aspect, the data amount of the reduced image data obtained by reducing the image data can be further reduced.

  Preferably, the erasing unit does not erase a portion having a predetermined length from a portion connected to another straight line among the specific lines in the character area.

  If this aspect is followed, the information which a specific line and a straight line connect can be hold | maintained.

  Preferably, the vector portion conversion means converts a specific line connected to another straight line among the specific lines in the character region into vector data as a specific line extending a predetermined length on the side connected to the other straight line. Including means.

  If this aspect is followed, the information which a specific line and a straight line connect can be hold | maintained.

  Preferably, the apparatus further includes thinning means for thinning a specific line in the character area included in the image data or the reduced image data.

  If this aspect is followed, the information which a specific line and a straight line connect can be hold | maintained.

  Preferably, the apparatus further includes a thickening unit that thickens a specific line in a character area included in the image data or the reduced image data.

  According to this aspect, information on the color of the specific line can be held.

  Preferably, the vector partial conversion means includes specific line extraction means for extracting a specific line in the character area.

  Preferably, the vector partial conversion unit removes the entire vector conversion unit that converts all lines in the character area into vector data and linear vector data having a slope within a predetermined range from the converted vector data. Removing means.

  Preferably, the image processing device further includes edge image generation means for generating an edge image from the acquired image data, and the vector partial conversion means converts a specific line in the character area extracted from the edge image into vector data.

  According to another aspect of the present invention, an image processing apparatus includes a data acquisition unit configured to acquire image data and vector data that includes the specific line in the character area of the image data, and the image data. Enlarging means for converting the data into high-resolution enlarged image data higher than the resolution of the image data, mask image generating means for generating a mask image in which the vector data is expanded at the resolution of the enlarged image data, and a mask for the enlarged image data Correction means for converting a portion protruding from the image into a background.

  According to this aspect, the image data is converted into high-resolution enlarged image data, a mask image in which the vector data is expanded at the resolution of the enlarged image data is generated, and the portion of the enlarged image data that protrudes from the mask image is converted into the background. The For this reason, the image processing apparatus which can reduce the noise which generate | occur | produces in the outline of the character in image data can be provided.

  According to still another aspect of the present invention, an image forming system includes the above-described image processing apparatus as a first image forming apparatus, and a set of reduced image data and vector data output from the first image processing apparatus. Input means for input, enlargement means for converting image data into high-resolution enlarged image data higher than the resolution of the image data, and development means for generating a specific line image in which vector data is developed at the resolution of the enlarged image data And combining means for combining the enlarged image data and the specific line image.

  According to this aspect, it is possible to provide an image processing system capable of retaining the shape of characters lost when image data is reduced and reducing the data amount as much as possible.

  According to still another aspect of the present invention, an image processing system includes the above-described image processing device as a first image forming device, and a set of reduced image data and vector data output from the first image processing device. Input means for input, enlargement means for converting reduced image data into high-resolution enlarged image data higher than the resolution of reduced image data, and a mask for generating a mask image in which vector data is expanded at the resolution of the enlarged image data A second image processing apparatus including: an image generating unit; and a correcting unit that converts a portion of the enlarged image data that protrudes from the mask image into a ground.

  If this aspect is followed, the image processing system which can reduce the noise which generate | occur | produces in the outline of the specific line in image data can be provided.

  According to still another aspect of the present invention, an image processing method includes a step of acquiring image data, a step of extracting a character region in which characters are represented from the acquired image data, and the extracted character region. A step of converting a specific line excluding a straight line having a slope within a predetermined range into vector data, a step of converting image data into reduced image data having a resolution lower than the resolution of the image data, reduced image data and vector data Outputting a set of.

  According to this aspect, it is possible to provide an image processing method capable of retaining the shape of characters lost when image data is reduced and reducing the amount of data as much as possible.

  According to still another aspect of the present invention, an image processing method includes only specific lines that are paired with image data and image data, excluding a straight line having a slope within a predetermined range in a character area of the image data. Obtaining vector data, converting the image data into high-resolution enlarged image data higher than the resolution of the image data, generating a mask image in which the vector data is expanded at the resolution of the enlarged image data, and Converting a portion of the enlarged image data that protrudes from the mask image into a background.

  If this situation is followed, the image processing method which can reduce the noise which generate | occur | produces in the outline of the specific line in image data can be provided.

  According to still another aspect of the present invention, an image processing program includes a step of acquiring image data, a step of extracting a character region in which characters are represented from the acquired image data, and a step in the extracted character region. A step of converting a specific line excluding a straight line having a slope within a predetermined range into vector data, a step of converting image data into reduced image data having a resolution lower than the resolution of the image data, reduced image data and vector data And a step of outputting a set of

  According to this aspect, it is possible to provide an image processing program that can retain the shape of characters lost when image data is reduced and can reduce the amount of data as much as possible.

  According to still another aspect of the present invention, an image processing program is a set of image data and image data, and includes only specific lines excluding a straight line having an inclination within a predetermined range in a character area of the image data. Obtaining vector data, converting the image data into high-resolution enlarged image data higher than the resolution of the image data, generating a mask image in which the vector data is expanded at the resolution of the enlarged image data, and A step of converting the portion of the enlarged image data that protrudes from the mask image into a background is executed by a computer.

  If this situation is followed, the image processing program which can reduce the noise which generate | occur | produces in the outline of the specific line in image data can be provided.

1 is a diagram showing an overall outline of an image processing system in an embodiment of the present invention. 2 is a block diagram illustrating an example of a hardware configuration of an MFP. FIG. It is a figure for demonstrating the noise which generate | occur | produces when reducing and enlarging the character image. 3 is a block diagram illustrating an example of an overview of an image compression function of a CPU provided in the MFP. FIG. It is a figure which shows an example of the detailed function of a vector partial conversion part. It is a figure which shows an example of the character image and vector data from which the specific line was partially erased. It is a figure for demonstrating a malfunction. It is a 1st flowchart which shows an example of the flow of an image compression process. It is a 1st flowchart which shows an example of the flow of a vector partial conversion process. It is a 1st flowchart which shows an example of the flow of a specific line partial erasing process. It is a figure which shows an example of the function of the vector partial conversion part in a modification. It is a 2nd flowchart which shows an example of the flow of the vector partial conversion process in a modification. 3 is a block diagram illustrating an example of an overview of an image expansion function of a CPU provided in the MFP. FIG. It is a flowchart which shows an example of the flow of an image expansion process. It is a block diagram which shows an example of the outline | summary of the image compression function in the 1st modification of CPU with which MFP is provided. It is a 1st figure which shows an example of the character image from which all the specific lines were erase | eliminated, and vector data. It is a 2nd flowchart which shows an example of the flow of an image compression process. It is a flowchart which shows an example of the flow of an extension process. It is a flowchart which shows an example of the flow of a specific line all deletion process. FIG. 10 is a block diagram illustrating an example of an overview of an image compression function in a second modification of the CPU provided in the MFP. It is a 3rd flowchart which shows an example of the flow of an image compression process. FIG. 10 is a block diagram illustrating an example of an overview of an image compression function of a CPU provided in an MFP according to a second embodiment. It is a 4th flowchart which shows an example of the flow of an image compression process. FIG. 10 is a block diagram illustrating an example of an overview of an image expansion function of a CPU provided in an MFP according to a second embodiment. (A) is a figure which shows an example of the character image in enlarged image data, (B) is a figure which shows an example of the character image and mask image in enlarged image data. 12 is a flowchart illustrating an example of a flow of image expansion processing according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram showing an overall outline of an image processing system according to an embodiment of the present invention. Referring to FIG. 1, an image processing system 1 includes a multi-function peripheral (hereinafter referred to as “MFP”) 100 and 100A, a personal computer (PC) 200, A server 311 and an electronic mail server 313 connected to the Internet 5.

  MFPs 100 and 100A are examples of image processing apparatuses, and have a plurality of functions such as a scanner function, a printer function, a copy function, and a facsimile function. Since the PC 300, the file server 311 and the e-mail server 313 are general computers and their hardware configurations and functions are well known, the description thereof will not be repeated here.

  The network 3 is a local area network (LAN), regardless of whether it is wired or wireless. The MFPs 100 and 100 </ b> A can communicate with each other via the network 3, and further can communicate with the file server 311 and the PC 300 connected to the network 3 and the electronic mail server 313 connected via the Internet 5. The network 3 is not limited to the LAN, and may be the Internet, a wide area network (WAN), a public switched telephone network, or the like.

  File server 311 can store image data accessible to MFP 100, 100 </ b> A and PC 300. The e-mail server 313 functions as a POP (Post Office Protocol) server and an SMTP (Simple Mail Transfer Protocol) server, and manages transmission / reception of e-mails.

  Since the hardware configurations and functions of the MFPs 100 and 100A are the same, the MFP 100 will be described as an example here. FIG. 2 is a block diagram illustrating an example of a hardware configuration of the MFP. Referring to FIG. 2, an MFP 100 includes a main circuit 101, an automatic document reader (ADF) 10, a document reading unit 20, an image forming unit 30, a paper feeding unit 40, and an operation panel 13 as a user interface. And including.

  The ADF 10 automatically conveys a plurality of documents set on the document feed tray one by one to a predetermined document reading position set on the platen glass of the document reading unit 20, and the document reading unit 20 reads the document. The document whose image has been read is discharged onto a document discharge tray. The document reading unit 20 includes a light source that emits light to the document conveyed to the document reading position and a photoelectric conversion element that receives light reflected from the document, and scans a document image corresponding to the size of the document. The photoelectric conversion element converts the received light into image data, which is an electrical signal, and stores it in a memory or outputs it to the image forming unit 30.

  The image forming unit 30 forms an image by a known electrophotographic method. The image forming unit 30 performs various types of data processing such as shading correction on the image data input from the document reading unit 20, and the image data after the data processing is processed. Based on this, an image is formed on the sheet conveyed by the sheet feeding unit 40. The paper feed unit 40 conveys the paper stored in the paper feed tray to the image forming unit 30.

  The main circuit 101 includes a CPU 111, a communication interface (I / F) unit 112, a ROM (Read Only Memory) 113, a RAM (Random Access Memory) 114, an EEPROM (Electronically Erasable and Programmable ROM) 115, and a large capacity. A hard disk drive (HDD) 116 as a storage device, a facsimile unit 117, a network I / F 118, and an external storage device 119 to which a CD-ROM (Compact Disk Read Only Memory) 119A is mounted are included. CPU 111 is connected to ADF 10, document reading unit 20, image forming unit 30, paper feeding unit 40, and operation panel 13, and controls the entire MFP 100.

  The ROM 113 stores a program executed by the CPU 111 and data necessary for executing the program. The RAM 114 is used as a work area when the CPU 111 executes a program.

  Communication I / F unit 112 is an interface for connecting MFP 100 to another apparatus using a serial communication cable. The connection form may be wired or wireless.

  The facsimile unit 117 is connected to a public switched telephone network (PSTN) and transmits facsimile data to the PSTN or receives facsimile data from the PSTN. The facsimile unit 117 stores the received facsimile data in the HDD 116 or outputs it to the image forming unit 30. The image forming unit 30 forms an image of facsimile data received by the facsimile unit 117 on a sheet. Further, the facsimile unit 117 converts the data stored in the HDD 116 into facsimile data, and transmits the facsimile data to a facsimile apparatus connected to the PSTN.

  A network I / F 118 is an interface for connecting the MFP 100 to the network 3. The CPU 111 can communicate with the MFP 100A, the PC 300, the file server 311 connected to the network 3 via the network I / F 118, and the electronic mail server 313 connected to the Internet.

  The external storage device 119 is loaded with a CD-ROM 119A. The CPU 111 can access the CD-ROM 119A via the external storage device 119, and can load a program stored in the CD-ROM 119A into the RAM 114 and execute it. Note that the program executed by the CPU 111 is not limited to the program stored in the CD-ROM 119A, and may be a program stored in another storage medium, a program stored in the HDD 116, or a network I / O. It may be a program written in the HDD 116 by another computer connected to the network 3 via F118.

  The storage medium for storing the program is not limited to the CD-ROM 119A, but an optical disc (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)), IC card, optical card, mask ROM, A semiconductor memory such as an EPROM (Erasable Programmable ROM) or an EEPROM (Electrically Erasable and Programmable ROM) may be used.

  The program here includes not only a program directly executable by the CPU 111 but also a source program, a compressed program, an encrypted program, and the like.

  Operation panel 13 is provided on the upper surface of MFP 100 and includes a display unit 103 and an operation unit 105. The display unit 103 is a display device such as a liquid crystal display device or an organic ELD (Electroluminescence Display), and displays an instruction menu for a user, information about acquired display data, and the like. The operation unit 105 receives a user operation and outputs the received operation to the CPU 111. The operation unit 105 includes a touch panel arranged so as to be superimposed on the display unit 103. The touch panel is made of a transparent member, and is arranged so as to be superimposed on the display unit 103. When the user touches the touch panel with a finger, the touch panel detects the touched position as an instruction position and outputs the detected position to the CPU 111.

  MFPs 100 and 100A as image processing apparatuses in the present embodiment have an image compression function for compressing image data and an image expansion function for expanding image data. In the present embodiment, an example will be described in which MFP 100 executes an image compression function and MFP 100A executes an image expansion function. Note that the image compression function is not limited to MFP 100 and may be executed by MFP 100A. Furthermore, the image expansion function is not limited to MFP 100A, and may be executed by MFP 100 or PC 300. That is, the process of compressing image data is executed by an input device to which image data is input, and the process of expanding compressed image data is executed by an output device to which compressed image data is input. An input device and an output device can be an apparatus that can execute an image processing program to be described later.

  Note that the image data compressed by MFP 100 may be stored in HDD 116 provided in MFP 100 or may be transmitted to another device. When the MFP 100 transmits the compressed image data, the transmission destination is the MFP 100A, the file server 311 and the PC 300. As a communication protocol for transmitting compressed image data from the MFP 100 to another apparatus, the MFP 100A, the file server 311 and the PC 300, a file transfer protocol (FTP) or the like can be used. However, the communication protocol is not limited to FTP. Other communication protocols such as SMB (Server Message Block) can be used. Alternatively, the compressed image data may be attached to an e-mail and transmitted via the e-mail server 313. Further, when the compressed image data is transmitted to MFP 100A, the format of the compressed image data may be raster data.

  When MFP 100 according to the present embodiment stores image data of a document read by document reading unit 20 in HDD 116 or transmits the image data to another device, for example, MFP 100A, the image data In order to reduce the amount of data, the image data is compressed and output. As one method for compressing image data, the image data is reduced so that the resolution is lowered. However, part of the image data is deleted by reducing the image data. On the other hand, in an output device that outputs compressed image data, here, MFP 100A, the compressed image data is expanded. In this case, when enlarging the reduced image data, it is impossible to accurately reproduce a portion lost in the image data at the time of reduction. In particular, in an oblique straight line or curve in a character, a portion deleted when it is enlarged cannot be accurately reproduced, and the contour becomes a stepped shape, and noise called so-called jaggy occurs. If a conventional character generator is used, it is possible to reduce the deterioration of the character image due to the reduction of the image.

  FIG. 3 is a diagram for explaining noise generated when a character image is reduced and enlarged. FIG. 3A shows an example of a character image. Here, the letters “heaven” are shown. This character has a straight line part and a curved line part. FIG. 3B shows an example of an enlarged image obtained by reducing the image shown in FIG. 3A and then enlarging the reduced image. In the enlarged image shown in FIG. 3B, it can be seen that a step-like jaggy is generated in the contour of the curved portion as compared with the image shown in FIG. This staircase noise appears on a line segment other than a curve in the character region and a line segment having an inclination within a predetermined range. A line segment having an inclination within a predetermined range is a line segment close to vertical or a line segment close to horizontal. The inclination within the predetermined range is a predetermined value. The inclination within the predetermined range may be determined by the resolution and the character size. Hereinafter, a line segment other than a curve in a character region and a line segment having an inclination within a predetermined range is referred to as a specific line.

  FIG. 4 is a block diagram illustrating an example of an outline of the image compression function of the CPU provided in the MFP. The functions of the CPU 111 shown in FIG. 4 are realized by the CPU 111 executing an image compression program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. The image compression program is a part of the image processing program.

  Referring to FIG. 4, the image compression function realized by CPU 111 includes an image data acquisition unit 51 that acquires image data, an edge image generation unit 53 that generates an edge image from image data, and characters that are displayed from the edge image. A character area extracting unit 55 for extracting the character area thus obtained, a vector part converting unit 57 for converting a specific line in the character area into vector data, and a specific line part erasing unit for erasing the specific line in the character area from the image data. 59, a reduction unit 61 that converts image data into reduced image data of lower resolution, and an output unit 63 that outputs a set of reduced image data and vector data.

  The image data acquisition unit 51 acquires image data output by the document reading unit 20 reading a document. Further, the image data acquisition unit 51 acquires the image data stored in the EEPROM 115 or the HDD 116 by reading it. Of the image data stored in the EEPROM 115 or the HDD 116, the user operates the operation unit 105 to acquire designated image data. The image data stored in the EEPROM 115 or the HDD 116 includes image data read by the document reading unit 20 and output, facsimile data received by the facsimile unit 117, and image data received from the outside by the network I / F 118 via the network 3. The communication I / F unit 112 includes image data read from an external memory connected thereto. The image data acquisition unit 51 outputs the acquired image data to the edge image generation unit 53 and the specific line part erasure unit 59.

  The edge image generation unit 53 generates an edge image by differentiating the image data input from the image data acquisition unit 51, and outputs the edge image to the character region extraction unit 55. The edge image generation unit 53 sets the value of the pixel in the image data to “1” when the difference between the pixel and the adjacent pixel adjacent in the horizontal direction is equal to or greater than a predetermined threshold, and the difference is a predetermined threshold. When the value is smaller than the value, an edge image with “0” is generated. In the edge image, a pixel having a pixel value “1” forms a contour of a character, line, or figure. In addition, since the technique which produces | generates an edge image is known, you may make it use other techniques, without being limited to this.

  The character region extraction unit 55 extracts a character region in which characters are represented from the edge image. The character area extraction unit 55 extracts a rectangular area including a plurality of pixels having a pixel value “1” in the edge image, and the period of change in the horizontal pixel value is less than or equal to a predetermined value in the rectangular area. In case, it is determined as a character area. In addition, since the technique which extracts a character area from an edge image is known, you may make it use another technique, without being limited to this. For example, without using an edge image, a rectangular area whose brightness change period of image data is a predetermined value or less may be extracted as a character area. The character region extraction unit 55 extracts a plurality of character regions when there are a plurality of character regions in the edge image. The character area extraction unit 55 outputs the edge image and the position of the character area in the edge image to the vector part conversion unit 57. Here, since the character region is a rectangular region, the position of the character region in the edge image is indicated by the coordinates of two opposing apex angles of the character region.

  The vector part conversion unit 57 converts a specific line among the lines specified by the outline included in the character area of the edge image into vector data, and outputs the vector data to the specific line part erasing unit 59 and the output unit 63. Details of the vector partial conversion unit 57 will be described later. The vector data output by the vector partial conversion unit 57 includes information on the resolution of the image data.

  The specific line part erasure unit 59 receives image data from the image data acquisition unit 51 and receives vector data from the vector part conversion unit 57. The specific line part erasing unit 59 specifies a specific line in the image data based on the vector data, and deletes a part of the specified specific line from the image data. Specifically, the specific line part erasing unit 59 replaces the value of the pixel constituting the specific line specified based on the vector data with the value of the pixel in the background area of the image data. When the end of the specific line specified based on the vector data is connected to another straight line, the specific line part erasing unit 59 is included in a part other than the non-erased part having a predetermined length from the connecting end. The pixel value is replaced with the pixel value of the background area of the image data. A well-known technique can be used as a method for extracting the base region. For example, a region other than a character region and including a pixel with the largest number of pixels having the same value may be used. The specific line part erasing unit 59 outputs the image data from which the specific line has been deleted to the reduction unit 61.

  The reduction unit 61 converts the image data from which the specific line has been deleted into reduced image data with a reduced resolution. The reduction unit 61 outputs the reduced image data to the output unit 63. The resolution of the reduced image data may be a predetermined resolution, may be determined based on the size of the image data, or may be a resolution set by the user inputting to the operation unit 105. Also good.

  The output unit 63 outputs a set of reduced image data input from the reduction unit 61 and vector data input from the vector partial conversion unit 57. The destination to which the output unit 63 outputs the set of reduced image data and vector data is determined by the output destination input to the operation unit 105 by the user. When the user designates MFP 100A or file server 311 as the output destination, output unit 63 transmits a set of reduced image data and vector data to MFP 100A or file server 311 via network I / F 118. When the user designates transmission by e-mail, the output unit 63 generates an e-mail that includes a set of reduced image data and vector data and sets an e-mail address designated by the user as a destination. The sent e-mail is transmitted to the e-mail server 313 via the network I / F 118. Further, when the user designates the EEPROM 115 or the HDD 116 as an output destination, the output unit 63 stores the set of the reduced image data and the vector data in the EEPROM 115 or the HDD 116.

  Since the reduced image data has a lower resolution than the image data, the data amount is smaller than that of the image data. Further, since the vector data output from the vector partial conversion unit 57 is obtained by converting only specific lines in the character area included in the image data, it is compared with the vector data obtained by converting all the lines constituting the characters in the character area. The amount of data is small.

  The vector partial conversion unit 57 outputs the vector data converted to the size corresponding to the resolution of the reduced image data reduced by the reduction unit 61 to the output unit 63 in order to match the vector data with the reduced image data. It may be. In the present embodiment, the vector partial conversion unit 57 converts the specific line in the image data into vector data. However, the specific part included in the reduced image data obtained by the reduction unit 61 reducing the image data. The line may be converted into vector data. In this case, the edge image generation unit 53 converts the reduced image data reduced by the reduction unit 61 into an edge image, and the specific line part deletion unit 59 deletes the specific line from the reduced image data.

  FIG. 5 is a diagram illustrating an example of detailed functions of the vector partial conversion unit. Referring to FIG. 5, the vector partial conversion unit 57 includes a specific line extraction unit 81 that extracts a specific line from the character region of the edge image, and a vector data generation unit 83 that generates vector data from the extracted specific line. Including. The specific line extraction unit 81 extracts a specific line from line segments included in the character region of the edge image. Specifically, the specific line extraction unit 81 detects the connection direction of the edges included in the edge image, and determines whether the connection direction is an edge within a predetermined range from the horizontal direction or a predetermined range from the vertical direction. It is determined that the line has an inclination within the range of.

  More specifically, the accumulated values ΣΔx and ΣΔy of absolute values of the horizontal direction difference Δx and the vertical direction difference Δy between two adjacent pixels are calculated between a plurality of pixels constituting the edge. If the cumulative value ΣΔy is equal to or greater than a predetermined threshold value, the edge is extracted as a specific line. If the cumulative value ΣΔx is smaller than a predetermined threshold value, it is determined that the connecting direction is an edge within a predetermined range from the vertical direction. If the cumulative value ΣΔy is smaller than the predetermined threshold value, the connecting direction is within a predetermined range from the horizontal direction. Judge the edge.

  The specific line extraction unit 81 outputs the extracted specific line to the vector data generation unit 83. The vector data generation unit 83 converts the specific line input from the specific line extraction unit 81 into vector data. Note that the method of extracting the specific line from the character region is not limited to the above method, and other methods may be used.

  FIG. 6 is a diagram illustrating an example of a character image and vector data in which the specific line is partially erased. FIG. 6 shows a character image and vector data in which a specific line is partially erased from the character image shown in FIG. Referring to FIG. 6, character image 211 in which the specific line is partially erased is an image obtained by removing parts 201 </ b> A and 203 </ b> A of specific lines 201 and 203 from the character “heaven”. Of these, a non-erasable portion 213 having a predetermined length from an end portion connected to the straight portion is included. The vector data 202 and 204 are generated from the specific lines 201 and 203, respectively, and are indicated by combinations of vectors along the center lines of the specific lines 201 and 203, and information such as line thickness information and end shape information. including. The character image shown in FIG. 3A can be reproduced from the character image 211 in which the specific line shown in FIG. 6 is partially erased and the vector data 202 and 204.

  On the other hand, the reason why the character image 211 in which the specific line shown in FIG. 6 is partially erased includes the non-erased part 213 of the specific lines 201 and 203 is to prevent the following problem from occurring. It is. When the character image 211 in which the specific line shown in FIG. 6 is partially erased does not include the non-erased portion 213 of the specific lines 201 and 203, the character image 211 in which the specific line is partially erased is It consists only of vertical straight lines. Therefore, the enlarged image after enlarging the character image 211 in which the specific line is partially erased and the specific line obtained by expanding the vector data 202 and 204 with the resolution after enlarging the reduced image data are not connected. There is a case.

  FIG. 7 is a diagram for explaining a problem. Referring to FIG. 7, the character image 211A obtained by enlarging the character image 211 in which the specific line shown in FIG. 6 is partially erased and the vector data 202 and 204 shown in FIG. 6 are developed at the resolution of the character image 211A. Lines 201A and 203A are shown. In the region 221, the character image 211A and the lines 201A and 203A obtained by expanding the vector data 202 and 204 at the resolution of the character image 211A are not combined.

  FIG. 8 is a first flowchart illustrating an example of the flow of image compression processing. The image compression processing is executed by the CPU 111 when the CPU 111 provided in the MFP 100 executes an image compression program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. Referring to FIG. 8, CPU 111 is in a standby state until image data is input (NO in step S01), and when image data is input (YES in step S01), the process proceeds to step S02. When the document reading unit 20 reads a document and outputs image data, the image data output by the document reading unit 20 is input.

  In step S02, an edge image is generated by differentiating the image data. An edge image in which a pixel value of a pixel having a pixel value difference between adjacent pixels equal to or greater than a predetermined threshold is “1” and a pixel value of a pixel having a difference smaller than the predetermined threshold is “0”. Generate. In the next step S03, a character region is extracted from the edge image. A rectangular region including a plurality of pixels having a pixel value of “1” is extracted from one image, and a character region is determined when the period of change in pixel values in the horizontal direction or the vertical direction is short in the rectangular region.

  In the next step S04, one of the character areas extracted in step S03 is selected as a processing target. In the next step S05, vector partial conversion processing is executed. Although details of the vector partial conversion process will be described later, this is a process for converting a specific line other than a vertical or horizontal line included in the character area into vector data. In the next step S06, a specific line certification cooperative process is executed. Although the details of the specific line erasing process will be described later, this is a process of erasing the specific line converted into vector data in step S05 from the image data input in step S01.

  In the next step S07, it is determined whether there is a character area that has not yet been selected as a processing target. If there is an unprocessed character area, the process returns to step S04; otherwise, the process proceeds to step S08. In step S08, the image data deleted from the specific center in step S06 is reduced to generate reduced image data. The image data is reduced by lowering the resolution of the image data.

  In the next step S09, a set of the reduced image data generated in step S08 and the vector data generated in step S05 is output, and the process ends. The output destination is determined by an instruction input to the operation unit 105 by the user. When the user designates MFP 100A or file server 311 as an output destination, a set of reduced image data and vector data is transmitted to MFP 100A or file server 311 via network I / F 118. In addition, when the user designates transmission by e-mail, an e-mail including a set of reduced image data and vector data and setting an e-mail address designated by the user as a destination is generated, and the generated e-mail is generated. The mail is transmitted to the electronic mail server 313 via the network I / F 118. Further, when the user designates the EEPROM 115 or the HDD 116 as an output destination, a set of reduced image data and vector data is stored in the EEPROM 115 or the HDD 116.

  FIG. 9 is a first flowchart showing an example of the flow of vector partial conversion processing. The vector partial conversion process is a process executed in step S05 in FIG. 8, and the character region selected in step S04 in the edge image generated in step S02 in FIG.

  Referring to FIG. 9, CPU 111 selects a line drawing from the edge image generated in step S02 of FIG. 8 (step S11). A line drawing is selected from the character region selected in step S04 in FIG. 8 as an edge image. The line drawing is composed of a plurality of pixels in which pixels having an image value “1” are continuous in the edge image. In the next step S12, it is determined whether or not the line drawing selected in step S11 is a horizontal line or a vertical line. If the selected line drawing is not a horizontal or vertical line, the process proceeds to step S13. If the selected line drawing is a horizontal line or a vertical line, step S13 is skipped and the process proceeds to step S14.

  In step S13, vector data is generated based on the line drawing selected in step S11, and the process proceeds to step S14. In step S14, it is determined whether or not there is an unselected line drawing that is not a processing target among the line drawings included in the character region selected in step S04 in FIG. If there is an unprocessed line drawing, the process returns to step S11; otherwise, the process returns to the image compression process.

  FIG. 10 is a first flowchart showing an example of the flow of the specific line part erasing process. The specific line part erasing process is a process executed in step S06 in FIG. 8, and the character region selected in step S04 in the image data input in step S01 in FIG. Further, the vector data generated in step S05 in FIG. 8 is used.

  Referring to FIG. 10, a specific line is selected from the image data input in step S01 of FIG. 8 (step S21). A specific line is selected from the image data based on the vector data generated in step S05 of FIG. 8 in the character area to be processed.

  In the next step S22, it is determined whether or not one of both ends of the specific line selected in step S21 is combined with another horizontal line or vertical line. If either one of both ends of the specific line is combined with another horizontal line or vertical line, the process proceeds to step S23; otherwise, the process proceeds to step S24.

  In step S23, the part excluding the non-erased part of the selected specific line is erased from the image data, and the process proceeds to step S25. Specifically, the pixel value included in the specific line selected in step S11 and excluding the non-erased portion is replaced with the pixel value of the background region of the image data.

  On the other hand, in step S24, the selected specific line is deleted from the image data, and the process proceeds to step S25. The value of the pixel included in the specific line selected in step S11 is replaced with the value of the pixel in the background area of the image data.

  In step S25, based on the vector data generated in step S05 in FIG. 8, among the specific lines included in the character area selected in step S04 in FIG. It is determined whether or not exists. If there is an unprocessed specific line, the process returns to step S21; otherwise, the process returns to the image compression process.

<Modification of vector partial conversion unit>
The vector part conversion unit 57 described above extracts a specific line from the edge image, and converts the extracted specific line into vector data. The vector partial conversion unit 57A in the modified example generates vector data of a specific line by converting all line drawings included in the edge image into vector data and then deleting the vector data of horizontal lines and vertical lines. Is.

  FIG. 11 is a diagram illustrating an example of a function of the vector partial conversion unit in the modification. Referring to FIG. 11, vector portion conversion unit 57A in the modification includes a vector data generation unit 83A and a horizontal / vertical line exclusion unit 85. The vector data generation unit 83A converts each line included in the character area of the edge image into vector data. The vector data generation unit 83A outputs the vector data to the horizontal / vertical line exclusion unit 85.

  The horizontal / vertical line excluding unit 85 deletes vector data of horizontal lines and vertical lines from the vector data input from the vector data generating unit 83A. The horizontal line vector data is a straight line, and the absolute value of the difference between the Y coordinates of the coordinate values at both ends is smaller than a predetermined range. The vector data of the vertical line is a vector data that is a straight line, and whose absolute value of the difference between the X coordinates of the coordinate values at both ends is smaller than a predetermined range. The horizontal / vertical line excluding unit 85 outputs the remaining vector data obtained by deleting the vector data of the horizontal line and the vertical line to the specific line part erasing unit 59 and the output unit 63.

  FIG. 12 is a second flowchart showing an example of the flow of vector partial conversion processing in the modification. Referring to FIG. 12, the vector partial conversion process in the modification is a process executed in step S05 of FIG. 8, and the character region selected in step S04 in the edge image generated in step S02 of FIG. To be processed. In addition, the same code | symbol is attached | subjected to the same process as the vector partial conversion process shown in FIG.

  Referring to FIG. 12, CPU 111 selects a line drawing from the edge image generated in step S02 of FIG. 8 (step S11). In the next step S13, vector data is generated based on the line drawing selected in step S11, and the process proceeds to step S14. In step S14, it is determined whether or not there is a line drawing not selected as a processing target among the line drawings included in the character region selected in step S04 in FIG. If there is an unprocessed line drawing, the process returns to step S11; otherwise, the process returns to the image compression process.

  In step S15, the horizontal line vector data is deleted from the vector data generated in step S13. Vector data that is a straight line and whose absolute value of the difference between the Y coordinate values of both ends is smaller than a predetermined range is deleted.

  In the next step S16, the vertical line vector data is deleted from the vector data generated in step S13, and the process returns to the image compression process. Vector data that is a straight line and whose absolute value of the difference between the X coordinates of the coordinate values at both ends is smaller than a predetermined range is deleted.

  Next, the image expansion function of CPU 111 provided in MFP 100A will be described. FIG. 13 is a block diagram illustrating an example of an overview of the image expansion function of the CPU provided in the MFP. The image expansion function of the CPU 111 shown in FIG. 13 is realized by the CPU 111 provided in the MFP 100A executing an image expansion program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. The image expansion program is a part of the image processing program.

  Referring to FIG. 13, the image expansion function implemented in CPU 111 provided in MFP 100 </ b> A includes an input unit 71 to which reduced image data and vector data are input, and an enlarged image having a resolution higher than the resolution of the reduced image data. An expansion unit 73 that converts data into data, a development unit 75 that generates a developed image including a line drawing in which vector data is developed at the resolution of the enlarged image data, and a synthesis unit 77 that synthesizes the line drawing with the enlarged image data are included.

  When the network I / F 118 receives the reduced image data and vector data from the MFP 100A, the input unit 71 receives the received reduced image data and vector data. The input unit 71 outputs the input reduced image data to the enlargement unit 73 and outputs vector data to the expansion unit 75. If the user operates the operation unit 105 to specify the reduced image data stored in the EEPROM 115 or the HDD 116, the specified reduced image data and the vector data paired with the reduced image data are read out. They are entered. Here, the reduced image data stored in the EEPROM 115 or the HDD 116 is reduced image data received from the MFP 100. Further, when the image compression function is realized in the CPU 111 provided in the MFP 100A, reduced image data generated by the CPU 111 provided in the MFP 100A may be used.

  The enlargement unit 73 converts the reduced image data input from the input unit 71 into high-resolution enlarged image data higher than the resolution. The resolution of the enlarged image data may be a predetermined resolution, or may be a resolution set by the user inputting to the operation unit 105. The enlargement unit 73 outputs the enlarged image data to the synthesis unit 77. Since the reduced image data input from the input unit 71 is image data in which the portion excluding the non-erased portion of the specific line in the character region is erased, the enlarged image data also includes the non-erased portion of the specific line in the character region. Does not include the excluded part.

  The developing unit 75 generates a developed image including a line drawing in which the vector data input from the input unit 71 is developed with the resolution of the enlarged image data. The developing unit 75 outputs the generated developed image to the synthesizing unit 77.

  The combining unit 77 generates a combined image obtained by combining the expanded image data input from the expanding unit 73 with the expanded image input from the expanding unit 75, and outputs the combined image. When the input unit 71 receives a set of reduced image data and vector data received from the MFP 100A by the network I / F 118, the combining unit 77 automatically combines the image forming unit 30 with no user operation. An image is formed on a sheet.

  Note that the output destination of the composite image may be determined by an instruction input by the user to the operation unit 105. When the user instructs the display unit 103 as an output destination, the composite image is displayed on the display unit 103. When the image forming unit 30 is instructed, the image forming unit 30 causes the composite image to be formed on a sheet. .

  FIG. 14 is a flowchart illustrating an example of the flow of image expansion processing. The image expansion processing is executed by the CPU 111 when the CPU 111 provided in the MFP 100A executes an image expansion program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. Referring to FIG. 14, CPU 111 is in a standby state until reduced image data and vector data are input (NO in step S51), and when reduced image data and vector data are input (YES in step S51). Then, the process proceeds to step S52. When network I / F 118 receives reduced image data and vector data from MFP 100A, the received reduced image data and vector data are input.

  In step S52, the input reduced image data is enlarged to generate enlarged image data. In the next step S53, a developed image obtained by developing the input vector data is generated. Then, a composite image is generated by combining the expanded image data with the developed image. In the next step S55, a composite image is output, and the process ends.

  As described above, when the CPU 111 executes the image compression program, the MFP 100 as the image processing apparatus converts the specific line of the image data into vector data, and in the character area extracted from the image data or the reduced image data. The specific line is deleted, the image data is converted into reduced image data having a low resolution, and a set of reduced image data and vector data is output. For this reason, the shape of the character lost by reducing image data can be included in vector data. Further, since all lines of characters are not converted to vector data, the amount of vector data can be reduced as much as possible. Further, since the portion excluding the non-erased portion of the specific line in the character area extracted from the image data or the reduced image data is deleted, the data amount of the reduced image data obtained by reducing the image data can be further reduced.

  Further, since the non-erased portion of the specific line in the image data or the reduced image data is not erased, the information connecting the specific line and the horizontal line or the vertical line can be held in the reduced image data.

<First Modification of Image Compression Function>
In MFP 100 in the above embodiment, in the image compression function realized by CPU 111, the specific line in the image data is used as vector data, and the part other than the non-erased part of the specific line is erased from the image data. . The image compression function in the first modification realized by the CPU 111 is different in that all parts of the specific line are erased from the image data. When the entire part of the specific line is erased from the image data, as shown in FIG. 7, the enlarged image and the specific line developed by the vector data may not be connected. In the first modification of the image compression function, the vector data of the specific line is extended at the connection portion, thereby reliably connecting the enlarged image and the specific line developed by the vector data.

  FIG. 15 is a block diagram illustrating an example of an outline of an image compression function in the first modification of the CPU provided in the MFP. The functions of the CPU 111 shown in FIG. 15 are realized by the CPU 111 executing an image compression program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. Referring to FIG. 15, the difference from the image compression function realized in CPU 111 shown in FIG. 4 is that specific line part erasing unit 59 is changed to specific line all erasing unit 59A, and extension unit 65 is added. It is a point. The other functions are the same as the functions shown in FIG. 4, and thus description thereof will not be repeated here.

  The vector partial conversion unit 57 converts a specific line out of the contour lines included in the character region of the edge image into vector data, and outputs the vector data to the entire specific line erasing unit 59A and the extension unit 65.

  The specific line all erasing unit 59A receives image data from the image data acquisition unit 51 and vector data from the vector partial conversion unit 57. The specific line all erasing unit 59A specifies specific lines in the image data based on the vector data, and erases all the specified specific lines from the image data. Specifically, the specific line part erasing unit 59 replaces the value of the pixel constituting the specific line specified based on the vector data with the value of the pixel in the background area of the image data. The specific line all erasing unit 59A outputs the image data from which the specific line has been deleted to the reduction unit 61.

  The extension unit 65 combines the vector data input from the vector partial conversion unit 57 with the horizontal line or the vertical line of the vector data corresponding to a specific line in which one of both ends is combined with another horizontal line or the vertical line. Extend the side by a predetermined length. The extension unit 65 outputs the extended vector data to the output unit 63.

  FIG. 16 is a first diagram illustrating an example of a character image and vector data from which all of the specific line has been erased. FIG. 16 shows a character image in which all the specific lines are erased from the character image shown in FIG. 3A and extended vector data. Referring to FIG. 16, character image 211 </ b> A from which all of the specific line has been deleted is an image obtained by removing specific lines 201 and 203 from the character “heaven”. The vector data 202A, 204A is generated based on the specific lines 201, 203, and the end on the side coupled with the character image 211A from which all of the specific lines are erased is the side of the character image 211A from which all of the specific lines are erased. Has been extended. The vector data 202A and 204A are indicated by a combination of vectors along the center lines of the specific lines 201 and 203, and include information such as line thickness information and end shape. The character image shown in FIG. 3A can be reproduced from the character image 211A from which all the specific lines shown in FIG. 16 are deleted and the vector data 202A and 204A.

  The reason why the image compression function in the first modified example extends the vector data 202A, 204A to the character image 211A side from which all of the specific lines are deleted as shown in FIG. This is to prevent the combined image obtained by combining the image obtained by expanding the vector data 202A and 204A with the image enlarged after reducing the character image 211A from which the character is deleted does not become the image shown in FIG. In other words, the character image 211A from which all of the specific lines are erased is reliably connected to the specific lines in which the vector data 202A and 204A are expanded.

  FIG. 17 is a second flowchart illustrating an example of the flow of image compression processing. 17, the difference from the image compression processing shown in FIG. 8 is that step S05A is added after step S05, and step S06 is changed to step S06A. Other processing is the same as the processing shown in FIG. 8, and therefore description thereof will not be repeated here.

  In step S05A, an extension process for extending the vector data is executed. In step S06A, a specific line all erasing process for erasing all the specific lines from the image data is executed.

  FIG. 18 is a flowchart illustrating an example of the flow of extension processing. The extension process is a process executed in step S05A of FIG. Referring to FIG. 18, in step S31, one of the vector data generated in step S05 of FIG. 17 is selected as a processing target. In the next step S32, it is determined whether or not the end of the selected vector data is combined with another straight line. If either one of both ends of the vector data is combined with another straight line, the process proceeds to step S33. If neither of both ends is combined with another straight line, step S33 is skipped and the process is performed. Proceed to step S34. In step S33, the vector data selected as the processing target is extended at the end on the combined portion side. The joint portion is an end portion that is joined to another straight line among both end portions of the vector data, and the length to be extended is determined in advance. The extending direction may be the same as the direction near the end of the vector data.

  In step S34, it is determined whether there is vector data not selected as a processing target. If unprocessed vector data exists, the process returns to step S31. If not, the process returns to the image compression process.

  FIG. 19 is a flowchart showing an example of the flow of the specific line all erasing process. The specific line all erasing process is a process executed in step S06A of FIG. 17, and the character area selected in step S04 in the image data input in step S01 of FIG. Further, the vector data generated in step S05 in FIG. 17 is used. Referring to FIG. 19, the difference from the specific line part erasing process shown in FIG. 10 is that steps S22 and S23 are deleted. Accordingly, the specific line is selected from the image data input in step S01 of FIG. 8 (step S21), and the selected specific line is deleted from the image data (step S24). The process is selected in step S04 of FIG. Executes for all the specific lines included in the text area.

<Second Modification of Image Compression Function>
In MFP 100 in the above embodiment, in the image compression function realized by CPU 111, the specific line in the image data is used as vector data, and the part other than the non-erased part of the specific line is erased from the image data. . The image compression function in the second modification realized by the CPU 111 is different in that the specific line in the image data is converted into a thin line having a narrow line width without deleting all or part of the specific line from the image data.

  FIG. 20 is a block diagram illustrating an example of an outline of an image compression function in a second modification of the CPU provided in the MFP. The image compression function of the CPU 111 shown in FIG. 20 is realized by the CPU 111 executing an image compression program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. Referring to FIG. 20, the difference from the image compression function realized by CPU 111 shown in FIG. 4 is that specific line part erasing unit 59 has been changed to specific line thinning unit 67. The other functions are the same as the functions shown in FIG. 4, and thus description thereof will not be repeated here.

  The specific line thinning unit 67 receives image data from the image data acquisition unit 51 and receives vector data from the vector partial conversion unit 57. The specific line thinning unit 67 specifies a specific line in the image data based on the vector data, and narrows the line width of the specified specific line. Specifically, the specific line thinning unit 67 calculates a predetermined number of pixels of the underlying region from both ends of a plurality of pixels arranged in the horizontal direction among the pixels constituting the specific line specified based on the vector data. Replace with value. The specific line thinning unit 67 outputs the image data in which the specific line is thinned to the reduction unit 61.

  Since the specific line is converted into a thin line, when the specific line included in the reduced image data is enlarged, the contour part becomes a jagged shape called jaggy, but the line of the specific line developed by the vector data Since the width is larger than the line width of the specific line included in the enlarged image, the jaggy is canceled by the specific line developed by the vector data. On the other hand, even if the specific line developed by the vector data is not connected at the connecting portion with the horizontal line or the vertical line, the specific line is connected by the specific line included in the enlarged image data. The line width of the specific line included in the enlarged image data is narrower than the line width of the specific line developed by the vector data, but is inconspicuous because the length is short.

  FIG. 21 is a third flowchart illustrating an example of the flow of image compression processing. Referring to FIG. 21, the difference from the image compression processing shown in FIG. 8 is that step S06 is changed to step S06B. Other processing is the same as the processing shown in FIG. 8, and therefore description thereof will not be repeated here. In step S06B, a specific line thinning process is executed. The specific line thinning process is a process in which the character area selected in step S04 in the image data input in step S01 is processed, and the line widths of all the specific lines in the character area are narrowed. In step S24 of FIG. 19, the process for deleting the specific line may be changed to a process for thinning the specific line.

<Second Embodiment>
MFP 100 according to the first embodiment deletes reduced image data obtained by erasing a portion of the character line of the image data other than the non-erased portion of the specific line or the entire specific line, or reducing image data obtained by narrowing the specific line. Along with the generation, vector data for specific lines was generated. In the image expansion process, the specific line is reproduced by expanding the vector data. When the specific line in the image data is monochromatic, the specific line having the same color as the specific line in the image data can be reproduced from the vector data by including the color information in the vector data. However, when the color of the specific line in the image data includes a plurality of colors, especially when the color is expressed by gradation, the amount of vector data increases if the vector data includes color information. End up.

  MFP 100 according to the second embodiment can be applied when a character included in image data has a plurality of colors, particularly when a color attached to a character has gradation.

  FIG. 22 is a block diagram illustrating an example of an overview of an image compression function of a CPU provided in the MFP according to the second embodiment. The image compression function of the CPU 111 shown in FIG. 22 is realized by the CPU 111 executing an image compression program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. Referring to FIG. 22, the difference from the image compression function implemented in CPU 111 shown in FIG. 4 is that specific line part erasing unit 59 is changed to specific line thickening unit 69. The other functions are the same as the functions shown in FIG. 4, and thus description thereof will not be repeated here.

  The specific line thickening unit 69 receives the image data from the image data acquisition unit 51 and the vector data from the vector partial conversion unit 57. The specific line thickening unit 69 specifies a specific line in the image data based on the vector data, and increases the line width of the specified specific line. Specifically, the specific line thickening unit 69 sets a pixel outside the predetermined number from both ends of a plurality of pixels arranged in the horizontal direction among the pixels constituting the specific line specified based on the vector data. Replace with the minimum pixel value. Here, the pixel value indicates luminance, and the higher the luminance, the larger the pixel value. The specific line thickening unit 69 outputs the image data with the specific line thickened to the reduction unit 61.

  FIG. 23 is a fourth flowchart illustrating an example of the flow of image compression processing. Referring to FIG. 23, the difference from the image compression processing shown in FIG. 8 is that step S06 is changed to step S06C. Other processing is the same as the processing shown in FIG. 8, and therefore description thereof will not be repeated here. In step S06C, a specific line thickening process is performed. The specific line thickening process is a process in which the character area selected in step S04 in the image data input in step S01 is processed, and all the line widths of the specific lines in the character area are increased. In step S24 of FIG. 19, the process for deleting the specific line may be changed to a process for thickening the specific line.

  Next, an image expansion function of the CPU provided in the MFP according to the second embodiment will be described. FIG. 24 is a block diagram illustrating an example of an overview of the image expansion function of the CPU provided in the MFP according to the second embodiment. The functions of the CPU 111 shown in FIG. 24 are realized by the CPU 111 executing an image expansion program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A. The image expansion program is a part of the image processing program.

  Referring to FIG. 24, the difference from the image expansion function in the first embodiment shown in FIG. 13 is that the synthesis unit 77 is changed to a correction unit 79. The correction unit 79 receives the enlarged image data from the enlargement unit 73 and the development image from the development unit 75. Since the enlarged image data input from the enlargement unit 73 is an image obtained by enlarging the reduced image data obtained by converting the specific line to be thick, the specific line has jagged noise but is thicker than the other lines. Further, even when the specific line has a gradation color whose density changes, the gradation is included. On the other hand, the developed image input from the developing unit 75 has the same line width as a line other than the specific line.

  The correcting unit 79 uses the developed image input from the developing unit 75 as a mask image, and corrects the enlarged image data using the mask image. Specifically, the pixel value of the portion of the specific line included in the enlarged image data that protrudes from the mask image is replaced with the value of the underlying pixel. Since the developed image input from the developing unit 75 does not include noise in the contour, noise existing in the contour of the specific line of the enlarged image data can be deleted.

  FIG. 25A is a diagram illustrating an example of a character image in the enlarged image data. FIG. 25A shows a character image 211B that is enlarged after the character image shown in FIG. Referring to FIG. 25A, character image 211B includes a portion 211A excluding the specific line and portions 205 and 207 in which the specific line is thickened.

  FIG. 25B is a diagram illustrating an example of a character image and a mask image in the enlarged image data. Referring to FIG. 25B, mask images 201 and 203 are specific lines reproduced by developing vector data 202 and 204. The areas 205 and 207 of the character image 211B have a larger area than the mask images 201 and 203. The correction unit 79 replaces portions of the character image 211B that protrude from the mask images 201 and 203 with the background pixel values. For this reason, the character image shown in FIG. 3A is reproduced, and staircase noise generated in the contour of the specific line can be reduced. Further, when the portions 205 and 207 of the character image 211B have a color including gradation, the color is maintained even after being corrected by the correction unit 79.

  FIG. 26 is a flowchart illustrating an example of the flow of image expansion processing according to the second embodiment. The image expansion processing in the second embodiment is executed by the CPU 111 when the CPU 111 provided in the MFP 100A executes an image expansion program stored in the ROM 113, the EEPROM 115, the HDD 116, or the CD-ROM 119A.

  Referring to FIG. 26, the difference from the image expansion processing shown in FIG. 14 is that step S53, step S54 and step S55 are changed to step S53A, step S54A and step S55A, respectively. Other processing is the same as the processing shown in FIG. 14, and therefore description thereof will not be repeated here.

  In step S53A, a mask image obtained by developing the input vector data is generated. Then, a corrected image is generated by replacing the pixel value of the portion of the specific line included in the enlarged image data that protrudes from the mask image with the value of the underlying pixel (step S54A). In the next step S55A, a corrected image is output, and the process ends.

  Since the specific line in the second embodiment is converted into a thick line, when the specific line included in the reduced image data is enlarged, the contour portion has a stepped shape. On the other hand, since the line width of the specific line in the enlarged image data is larger than the line width of the specific line (mask image) developed by the vector data, it protrudes from the mask image. Since the portion that protrudes from the mask image is converted into the background, the stepped shape existing in the contour portion of the specific line in the enlarged image can be erased. On the other hand, even if the specific line in the image data has a plurality of colors, the specific line in the enlarged image also has a plurality of colors. For this reason, it is not necessary to include color information in the vector data, and the amount of vector data can be made as small as possible.

  In the above-described embodiment, the MFPs 100 and 100A have been described as examples of the image processing apparatus. However, the image compression processing illustrated in FIGS. 8, 17, 21, and 24, or the image compression processing illustrated in FIGS. It goes without saying that the invention can be understood as an image processing method for causing the MFP 100 to execute the image expansion processing or an image processing program for causing the computer to execute the image processing method.

  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.

<Appendix>
(1) The image processing apparatus according to (2), wherein the reduction unit reduces the image data after the curve is erased.

DESCRIPTION OF SYMBOLS 1 Image processing system, 3 networks, 5 Internet, 10 ADF, 13 Operation panel, 20 Original reading part, 30 Image formation part, 40 Paper feed part, 51 Image data acquisition part, 53 Edge image generation part, 55 Character area extraction part 57, 57A Vector partial conversion unit, 59 specific line partial erasing unit, 59A specific line all erasing unit, 61 reduction unit, 63 output unit, 65 extension unit, 67 specific line thinning unit, 69 specific line thickening unit, 71 Input unit 73 Enlargement unit 75 Development unit 77 Synthesis unit 79 Correction unit 81 Specific line extraction unit 83, 83A Vector data generation unit 85 Horizontal / vertical line exclusion unit 100, 100A MFP, 101 Main circuit, 103 display unit, 105 operation unit, 111 CPU, 112 communication I / F unit, 113 ROM, 114 RAM, 115 EEPROM, 116 HDD, 117 Facsimile part, 118 Network I / F, 119 Card I / F, 119A CD-ROM.

Claims (16)

Image data acquisition means for acquiring image data;
A character region extraction means for extracting a character region in which characters are represented from the acquired image data;
A vector partial conversion means for converting a specific line excluding a line segment having an inclination within a predetermined range in the extracted character area into vector data;
Reduction means for converting the image data into reduced image data having a resolution lower than the resolution of the image data;
An image processing apparatus comprising: output means for outputting a set of the reduced image data and the vector data.   The image processing apparatus according to claim 1, further comprising an erasing unit that erases the specific line in the character region extracted from the image data or the reduced image data.   The image processing apparatus according to claim 2, wherein the erasing unit does not erase a portion having a predetermined length from a portion connected to another straight line in the character area.   The vector part converting means is an extension that converts a specific line connected to another straight line among the specific lines in the character area into vector data as a specific line extending a predetermined length on the side connected to another straight line. The image processing apparatus according to claim 2, comprising means.   The image processing apparatus according to claim 1, further comprising a thinning unit that thins the specific line in the character area included in the image data or the reduced image data.   The image processing apparatus according to claim 1, further comprising a thickening unit that thickens the specific line in the character area included in the image data or the reduced image data.   The image processing apparatus according to claim 1, wherein the vector partial conversion unit includes a specific line extraction unit that extracts the specific line in the character region. The vector part conversion means is an overall conversion means for converting all of the lines in the character area into vector data;
The image processing apparatus according to claim 1, further comprising: a removing unit that removes linear vector data having an inclination within a predetermined range from the converted vector data. An edge image generation means for generating an edge image from the acquired image data;
The image processing apparatus according to claim 1, wherein the vector partial conversion unit converts a specific line in the character region extracted from the edge image into vector data. Data acquisition means for acquiring image data and vector data that is combined with the image data and includes only specific lines in the character area of the image data;
Enlarging means for converting the image data into high-resolution enlarged image data higher than the resolution of the image data;
A mask image generating means for generating a mask image in which the vector data is developed at the resolution of the enlarged image data;
An image processing apparatus comprising: correction means for converting a portion of the enlarged image data that protrudes from the mask image into a ground. A first image processing apparatus according to any one of claims 1 to 5 and any one of claims 7 to 9 dependent on any one of claims 1 to 5;
An input means for inputting a set of the reduced image data and the vector data output from the first image processing apparatus;
Enlarging means for converting the image data into high-resolution enlarged image data higher than the resolution of the image data;
Developing means for generating a specific line image obtained by expanding the vector data at a resolution of the enlarged image data;
An image processing system comprising: a second image processing device including a synthesizing unit that synthesizes the enlarged image data and the specific line image. A first image processing apparatus according to claim 6 and any one of claims 7 to 9 dependent on claim 6;
An input means for inputting a set of the reduced image data and the vector data output from the first image processing apparatus;
Enlarging means for converting the reduced image data into high-resolution enlarged image data higher than the resolution of the reduced image data;
A mask image generating means for generating a mask image in which the vector data is developed at the resolution of the enlarged image data;
A second image processing apparatus comprising: a correction unit that converts a portion of the enlarged image data that protrudes from the mask image into a background. Obtaining image data; and
Extracting a character region in which characters are represented from the acquired image data;
Converting a specific line excluding a straight line having a slope within a predetermined range in the extracted character region into vector data;
Converting the image data into reduced image data having a resolution lower than the resolution of the image data;
Outputting a set of the reduced image data and the vector data. Obtaining image data and vector data including only specific lines excluding a straight line having a slope within a predetermined range in a character area of the image data in combination with the image data;
Converting the image data into high-resolution enlarged image data higher than the resolution of the image data;
Generating a mask image in which the vector data is developed at a resolution of the enlarged image data;
Converting the portion of the enlarged image data that protrudes from the mask image into a ground, and an image processing method. Obtaining image data; and
Extracting a character region in which characters are represented from the acquired image data;
Converting a specific line excluding a straight line having a slope within a predetermined range in the extracted character region into vector data;
Converting the image data into reduced image data having a resolution lower than the resolution of the image data;
An image processing program for causing a computer to execute a step of outputting a set of the reduced image data and the vector data. Obtaining image data and vector data including only specific lines excluding a straight line having a slope within a predetermined range in a character area of the image data in combination with the image data;
Converting the image data into high-resolution enlarged image data higher than the resolution of the image data;
Generating a mask image in which the vector data is developed at a resolution of the enlarged image data;
A step of converting a portion of the enlarged image data that protrudes from the mask image into a ground, and an image processing program executed by a computer;

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