JP2008141384A - Image processing apparatus and image processing program - Google Patents

Abstract

An image processing apparatus and an image processing program capable of discriminating the type of a document with a simple configuration and performing an appropriate correction according to the type.
A pixel having a low density has a pixel value converted to “1”, and detects whether the pixel converted to “1” forms a straight line (S6). When a straight line is detected, the length of the straight line is detected, and the number of straight lines whose detected length is equal to or greater than a predetermined length is counted and stored in the straight line count memory 23b (S7). Next, it is determined whether or not the count value stored in the straight line count memory 23b is a predetermined number M or more (S8). When the number of detected straight lines is equal to or greater than the predetermined number M (S8: Yes), it is determined that the predetermined format exists and the original is copied using carbon paper, and the main scan is performed to increase the density. The pixel value is changed so as to be output to the printer unit 2 (S12).
[Selection] Figure 5

Description

  The present invention is an image processing apparatus and an image processing program, and can determine whether or not a predetermined format is included in a document with a particularly simple configuration, and perform appropriate density correction according to the type of the document. The present invention relates to an image processing apparatus and an image processing program.

  When an image drawn on a document is read and printed, a darkly drawn portion can be identified, but a thinly drawn portion may be difficult or impossible to identify.

  Also, when color image data is printed as a monochrome image, or when color image data is received by facsimile and printed as a monochrome image, when printing as a color image, an image that can be identified is identified as a monochrome image. It may become impossible or unclear.

  In particular, when images such as slips, forms, and application forms are scanned using carbon paper, and when the image data is printed as a monochrome image, the characters transferred by carbon paper are used. Depending on the color of a straight line such as a form originally printed on a sheet, the form itself may not be printed clearly.

  In Japanese Patent Application Laid-Open No. 8-44818 (Patent Document 1), when carbon paper can be used to write characters on a plurality of papers at a time, the paper overlapped below becomes thinner. A technique is disclosed in which an identification mark for identifying the number of sheets from above is added to a sheet in advance, and the density of the image is changed by determining the identification mark.

Japanese Patent Application Laid-Open No. 2000-287090 (Patent Document 2) discloses an apparatus that darkly controls a color image having a low contrast to make the image easy to see and have a good appearance. Japanese Patent Laid-Open No. 2000-301877 (Patent Document 3) discloses that when an image of a sheet written with a marker pen of a color such as red or blue is formed, the density is low and difficult to read. An apparatus is disclosed in which light is irradiated through a band-pass filter so that the density of red or blue is the same as that of black.
JP-A-8-44818 JP 2000-287090 A Japanese Patent Laid-Open No. 2000-301887

  However, in the apparatus described in Patent Document 1, the density can be adjusted only when an identification mark is added to the paper. However, when the identification mark is not added to the paper, the density is adjusted. There was a problem that it was not possible.

  In addition, since the device described in Patent Document 2 controls dark portions with low contrast, even in the case of an image such as a landscape image, it controls dark portions with low contrast and corrects them to inappropriate images. There was a problem.

  Similarly, in the apparatus described in Patent Document 3, red and blue are controlled to be dark, and even in the case of an image such as a landscape image, red and blue are controlled to be dark and corrected to an inappropriate image. There was a problem.

  The present invention has been made in order to solve the above-described problems. An image processing apparatus and an image processing program that can determine the type of a document with a simple configuration and perform appropriate density correction according to the type. The purpose is to provide.

  To achieve this object, an image processing apparatus according to claim 1 of the present invention comprises a reading unit that reads an image recorded on a document and acquires image data, and image data acquired by the reading unit. Formed by a density determination means for determining whether or not the density value of each pixel to be included is within a predetermined range value, and a pixel group for which the density value is determined to be included in the predetermined range by the density value determination means Based on the straight line detection means for detecting a straight line having a predetermined length or more and information on the straight line detected by the straight line detection means, whether or not a predetermined format formed by the straight line exists in the image. If the format determining means determines that the predetermined format exists in the image, the density value of each pixel constituting the image data read by the reading means is When the format determining unit determines that the predetermined format does not exist in the image, the density value of each pixel constituting the image data read by the reading unit is output. Output means for outputting without changing so that the density becomes high.

  The image processing device according to claim 2 is the image processing device according to claim 1, wherein the image data is color image data, and density values of the pixels are an R value, a G value, and a B value, The density determination means determines a pixel having a low density by determining whether or not the density values of the R value, the G value, and the B value are within a predetermined range.

  According to a third aspect of the present invention, there is provided the image processing apparatus according to the first or second aspect, further comprising a document size detecting unit that detects a size of a document on which an image read by the reading unit is recorded, The length is set according to the size of the document detected by the document size detecting means.

  The image processing device according to claim 4 is the image processing device according to any one of claims 1 to 3, wherein the number of straight lines counting the number of straight lines having a predetermined length or more detected by the straight line detecting means. The format determining means determines whether or not the read image of the document includes a predetermined format based on the number of straight lines detected by the straight line number detecting means.

  The image processing apparatus according to claim 5, further comprising a frame detection unit that detects a frame formed by the straight line detected by the straight line detection unit in the image processing apparatus according to claim 1, and the format The determination unit determines whether or not the image of the original read based on the frame detected by the frame detection unit includes a predetermined format.

  An image processing apparatus according to claim 6 is an image processing apparatus according to claim 5, further comprising area calculation means for obtaining an area inside the frame detected by the frame detection means, wherein the format determination means is the area calculation means. Based on the area inside the frame calculated by the above, it is determined whether or not the read image of the document includes a predetermined format.

  The image processing device according to claim 7 is the image processing device according to claim 6, wherein the number of frames in which the area inside the frame calculated by the area calculation means is equal to or larger than a predetermined area is counted. Means for determining whether the image of the read document includes a predetermined format based on the number of frames counted by the frame number counting unit.

  The image processing device according to claim 8 is the image processing device according to any one of claims 1 to 7, wherein the reading unit is a prescan unit that acquires image data of an image with a predetermined resolution by color reading; Main scanning means for acquiring image data of the image at a resolution higher than the predetermined resolution by monochrome reading, and the density determination means is a density value of each pixel constituting the image data acquired by the pre-scanning means Is included in a value within a predetermined range, and the output means acquires the main scanning means when the format determining means determines that the predetermined format exists in the image. The density value of each pixel constituting the image data is changed and output so that the density is high, and the format judging means does not have a predetermined format in the image. And if it is determined to output the density value of each pixel constituting the image data acquired by the main scan means without changing to a concentration of darker.

  The image processing program according to claim 9 is executed by a computer that inputs image data acquired by a reading device that reads an image and processes the image data, and each of the image data constituting the input image data A density determination step for determining whether or not the density value of a pixel is included in a predetermined range value, and a pixel group that is determined to be included in the predetermined range by the density value determination step. A straight line detecting step for detecting a straight line having a predetermined length or more and whether or not a predetermined format formed by the straight line exists in the image based on the straight line information detected by the straight line detecting step. A format determining step to determine, and when it is determined by the format determining step that a predetermined format exists in the image, each of the image data The density value of each pixel constituting the image data is output when the density value of the element is changed so as to increase the density, and the format determining means determines that the predetermined format does not exist in the image. And an output step for outputting without changing so that the density becomes high.

According to the image processing apparatus of claim 1, the reading unit acquires image data of an image recorded on a document, and the density determination unit is a density value of each pixel constituting the image data acquired by the reading unit. The straight line detection means determines whether the density value is included in the predetermined range by the density value determination means. The straight line is detected, the format determining means determines whether or not a predetermined format formed by the straight line exists in the image based on the straight line information detected by the straight line detecting means, and the output means When it is determined by the format determining means that a predetermined format exists in the image, the density value of each pixel constituting the image data is changed so as to increase the density, and the image is determined by the format determining means. If the prescribed format does not exist If it is the cross-sectional, and outputs the density value of each pixel constituting the image data read by the reading means without changing to a concentration of darker.
Therefore, when a document including a straight line composed of a group of pixels having a relatively low density and including a predetermined format constituted by these straight lines is copied, the adjustment is automatically performed so that the density is increased. Since it is printed, it can be prevented that the contents of the image cannot be identified.

  According to the image processing apparatus of the second aspect, in addition to the effect produced by the image processing apparatus of the first aspect, the image data is color image data, and the pixel density values are R value, G value, and B value. The density determination means determines pixels having low density by determining whether the density values of the R value, G value, and B value are within a predetermined range. A pixel having a low density can be accurately discriminated, and it can be discriminated that the pixel is thin and whether or not a straight line is formed for the pixel can be detected.

  According to the image processing apparatus of the third aspect, in addition to the effect produced by the image processing apparatus of the first or second aspect, the document size detecting means for detecting the size of the document on which the image read by the reading means is recorded is provided. The predetermined length is set according to the size of the document detected by the document size detecting means. In general, the length of the straight line constituting the format changes according to the document size, and it is considered that the larger the document size, the longer the straight line length, and the smaller the document size, the shorter the straight line length. If the predetermined length is made constant regardless of the original size, it will be determined whether or not the predetermined format exists by mistake. However, by setting the predetermined length according to the original size, it is possible to accurately It is possible to determine whether or not a predetermined format exists.

  According to the image processing apparatus of the fourth aspect, in addition to the effect produced by the image processing apparatus according to any one of the first to third aspects, the number of straight lines having a predetermined length or more detected by the straight line detecting means is counted. And a format determining unit determines whether the read document image includes a predetermined format based on the number of straight lines detected by the line number detecting unit. Usually, the predetermined format is often composed of a plurality of straight lines. Therefore, if the number of straight lines composed of thin pixels is small, it is determined that the predetermined format is not included, and the image density is higher than necessary. It is possible to prevent the adjustment from being performed so that it becomes darker.

  According to the image processing device of claim 5, in addition to the effect produced by the image processing device according to any one of claims 1 to 3, a frame detection unit for detecting a frame formed by a straight line detected by the straight line detection unit. The format determining means determines whether the image of the document read based on the frame detected by the frame detecting means includes a predetermined format. Usually, the predetermined format often includes a frame that becomes an entry field. Therefore, if a frame composed of thin pixels is not detected, it is determined that the predetermined format is not included, and the image density is higher than necessary. It is possible to prevent the adjustment from being performed.

  According to the image processing device of claim 6, in addition to the effect produced by the image processing device of claim 5, the image processing device includes area calculation means for obtaining an area inside the frame detected by the frame detection means, and the format determination means includes: Based on the area inside the frame calculated by the area calculating means, it is determined whether or not the read image of the document includes a predetermined format. In general, the predetermined format often includes a frame serving as an entry field, and the frame is secured to a certain size so that characters and the like can be written therein. For this reason, even if a frame composed of thin pixels is detected, if the area of the frame is inappropriate for text entry, etc., it is determined that the predetermined format is not included, and the image is unnecessarily large. It is possible to prevent the adjustment from being performed so that the density of the image becomes higher.

  According to the image processing apparatus of the seventh aspect, in addition to the effect produced by the image processing apparatus of the sixth aspect, the number of frames in which the area inside the frame calculated by the area calculating means is equal to or larger than a predetermined area is calculated. Frame number counting means for counting is provided, and the format determining means determines whether or not the read document image includes a predetermined format based on the number of frames counted by the frame number counting means.

  In general, the predetermined format often includes a frame serving as an entry field, and the frame is secured to a certain size so that characters and the like can be written therein. In addition, since there are often multiple numbers, even if the frame is composed of thin pixels and has a size larger than a predetermined area, if the number of frames is small, a predetermined format is included. Therefore, it is possible to prevent the adjustment from being performed so that the image density becomes higher than necessary.

  According to the image processing apparatus of the eighth aspect, in addition to the effect produced by the image processing apparatus according to any one of the first to seventh aspects, the reading unit acquires image data of an image with a predetermined resolution by color reading. A pre-scanning unit and a main-scanning unit that acquires image data of an image at a resolution higher than a predetermined resolution by monochrome reading, and the density determination unit includes a density of each pixel constituting the image data acquired by the pre-scanning unit It is determined whether or not the value is included in a value within a predetermined range, and the output unit determines that the predetermined format is present in the image by the format determination unit and outputs the image data acquired by the main scanning unit. If the density value of each pixel is changed so that the density is increased and output, and the format determining means determines that the predetermined format does not exist in the image, this The density value of each pixel constituting the image data acquired by the down means outputs without changing to a concentration of darker. Therefore, the capacity of the memory for storing the image data can be reduced, and the memory can be used efficiently.

  That is, the image data of the document is acquired at a high resolution, stored in the image memory, and it is determined whether or not the predetermined format exists in the image. If the density value of the image data is converted to dark and the predetermined format does not exist, the image data in the image memory can be output as it is, and the process can be completed with a single scan. For example, the capacity of the image memory used for other processing is limited. Therefore, pre-scanning scans at a low resolution, stores all images of the document in the image memory, determines whether or not a predetermined format exists, and after that determination, performs a main scan at a high resolution, Several lines can be sequentially stored in the image memory to perform necessary processing and output. By doing so, the capacity of the image memory to be used can be reduced.

  According to the image processing program of claim 9, a density determination step for determining whether or not a density value of each pixel constituting the input image data is included in a predetermined range of values, and a density value determination step thereof Based on the straight line detection step for detecting a straight line having a predetermined length or more formed by the pixel group determined to be included in the predetermined range by the density value, and the straight line information detected by the straight line detection step. A format determining step for determining whether or not a predetermined format formed by a straight line exists in the image, and if the format determining step determines that the predetermined format exists in the image, the input image If the density value of each pixel constituting the data is changed so that the density is increased and output, and the format determining means determines that the predetermined format does not exist in the image, it is input And an output step for outputting the density value of each pixel constituting the image data without changing the density so that the density becomes high.Therefore, by installing and executing this image processing program in a computer or the like, The same effect as that of the first aspect can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing an external configuration of a multifunction peripheral device (hereinafter abbreviated as “MFP (Multi Function Peripheral) or (Multi Function Printer)”) 1 according to an embodiment of the present invention. As shown in FIG. 1, the MFP 1 integrally includes a printer unit 2 provided at a lower part, a scanner part 3 provided at an upper part, and an operation panel 4 provided on the front side of the scanner part 3. A printer function, a scanner function, a copy function, and a facsimile function.

  The MFP 1 is connected to a computer (not shown), and records an image or document on a recording sheet (recording medium) based on image data or document data transmitted from the computer, or an external device such as a digital camera. It is possible to record image data output from a digital camera connected to a recording sheet, or to load various storage media such as a memory card and record the image data stored in the storage medium on a recording sheet. It is. Needless to say, the MFP 1 can record an image not only on a recording sheet but also on an OHP transparent film sheet or cloth (both are examples of a recording medium).

  The scanner unit 3 includes a document cover 8 provided with an automatic document feeder (ADF) 7 for a document reading table 6 that functions as an FBS (Flatbed Scanner). It is attached so that it can be opened and closed with its hinge as a fulcrum.

  The upper surface of the document reading table 6 is greatly opened, and a platen glass is fitted into the opening. Inside the document reading table 6, the moving space of the image reading unit, the image reading unit, and a member that supports the image reading unit 6 In addition, a space for arranging a driving mechanism and the like is secured.

  The ADF 7 transports the document from the document tray 9 to the document discharge tray 10 through the document transport path. The printer unit 2 records an image on a recording sheet by selectively ejecting ink droplets based on image data read by the scanner unit 3 or image data input from the outside. A recording apparatus (inkjet recording apparatus). As described above, the printer unit 2 is disposed below the scanner unit 3. An opening 5 is formed on the front side of the MFP 1, in other words, on the front side of the printer unit 2. A paper feed tray 14 and a paper discharge tray 15 are provided in the opening 5 so as to be completely contained. The paper feed tray 14 and the paper discharge tray 15 are arranged in two upper and lower stages, the paper discharge tray 15 is provided in the upper stage, and the paper feed tray 14 is provided in the lower part.

  A horizontally long operation panel 4 is provided on the front side of the MFP 1 as shown in FIG. The operation panel 4 is for operating the printer unit 2 and the scanner unit 3 and includes various operation keys 40 and a liquid crystal display (LCD) 41 (hereinafter referred to as a display screen). This display screen 41 has two screens with an aspect ratio of 3: 4 arranged side by side and an aspect ratio of 3: 8.

  The user can input a desired command using the operation panel 4. When a predetermined command is input to the MFP 1, the operation of the MFP 1 is controlled by the control unit 20 (see FIG. 2) based on the input information. The operation keys 40 provided on the operation panel 4 include a cross key 40a, a numeric keypad 40b, and the like.

  The MFP 1 is configured to operate based on a command input from the operation panel 4 and a command transmitted from the computer via a printer driver, a scanner driver, or the like in addition to the command input from the operation panel 4.

  A connection panel 70 is provided above the opening 5 of the printer unit 2. The connection panel 70 is provided with a USB terminal 71 on the left end side thereof. The USB terminal 71 is a connector terminal that communicatively connects the external device and the MFP 1 by making a USB connection with the external device. A slot portion 72 is disposed on the right end side of the connection panel 70. The slot portion 72 is provided with a plurality of card slots into which card type memories can be loaded. When a card-type memory is loaded in the card slot and image data is read from the loaded card-side memory by the control unit 20 described later, the read image data and information related to the image data are displayed by the control unit 20. It is displayed on the screen 41. Alternatively, the selected arbitrary image is recorded on the recording paper in the printer unit 2.

  Next, an outline of the electrical configuration of the MFP 1 will be described with reference to FIG. FIG. 2 is a block diagram showing an electrical configuration of the MFP 1. The control unit 20 controls the overall operation of the MFP 1 including the printer unit 2, the scanner unit 3, and the operation panel 4. As shown in FIG. 2, the control unit 20 is configured as a microcomputer mainly including a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, and a flash memory 24. The ASIC (Application Specific Integrated Circuit) 26 is connected via the bus 25.

  The ROM 22 stores various control programs for controlling the FAX function, copy function, scanner function, etc., constants and tables used in the control program, an image processing program 22a described later, and the like.

  The RAM 23 is a memory that can be accessed at random, and temporarily stores variables and parameters when the CPU 21 executes various functions. The RAM 23 stores the color image data read by the scanner unit 3 when performing facsimile transmission or copy printing, and the color image data stored in the image memory 23a. When a straight line having a predetermined length or more is detected in the read image, and there are a plurality of straight lines, the straight line count memory 23b for counting the number of straight lines, and when there are a plurality of straight lines, the straight lines are rectangular frames. And a frame count memory 23c, which is a memory for counting the number of frames, is provided. The detection of the straight line and the detection of the frame will be described later.

  The ASIC 26 controls the operation of the printer unit 2, the scanner unit 3, the operation panel 4, and the slot unit 72 in accordance with instructions from the CPU 21. Connected to the ASIC 26 is a panel gate array 27 for controlling operation keys 40 for inputting a desired command to the MFP 1. The panel gate array 27 detects the pressing of the operation key 40 and outputs a predetermined key code to the ASIC 26.

  An LCD controller 28 that controls the screen display of the display screen 41 is connected to the ASIC 26. The LCD controller 28 causes the display screen 41 to display information relating to the operation of the printer unit 2 or the scanner unit 3, a read image, or an input image on the screen based on a command from the CPU 21.

  Connected to the ASIC 26 are a parallel interface 29 and a USB terminal 71 for transmitting and receiving data to and from the computer via a parallel cable or a USB cable. Further, the ASIC 26 is connected to an NCU (Network Control Unit) 31, a modem 32, and a slot unit 72 for realizing a facsimile function.

  The slot portion 72 is provided with a plurality of card slots into which card-type memories can be loaded. When a card-type memory is loaded in the card slot and image data is read from the loaded card-side memory by the control unit 20, the read image data and information related to the image data are displayed on the display screen 41 by the control unit 20. Is displayed. Alternatively, an arbitrary image selected by the operation key 40 is recorded on the recording paper in the printer unit 2.

  Next, examples of various originals will be described with reference to FIG. FIG. 3 shows three types of documents. 3A and 3B are determined to be a document including a predetermined format, and (c) is determined not to be a document including a predetermined format. 3A and 3B are determined to be, for example, an original made of carbon paper or an original in which characters are written using carbon paper (hereinafter referred to as a carbon paper original).

  Specifically, FIG. 3A is an example showing a manuscript in which the entry field is drawn with, for example, a green straight line as indicated by an arrow. Some forms and the like written using carbon paper have a plurality of straight lines indicating entry columns in various colors, as shown in FIG. These straight lines have, for example, a length that is equal to or longer than a predetermined length such that a name, an address, and the like can be entered. If the light source used for scanning is, for example, green, the green straight line is output as image data with a low density. Therefore, an image including a straight line made up of a group of pixels having a relatively low density as the predetermined density and in which a plurality of straight lines with a predetermined length or more are drawn at the predetermined density is printed in advance on a form or the like. Is determined to be in a predetermined format (entry field). Of these straight lines, some straight lines often have the same length and the same direction (the horizontal direction in the figure).

  In addition, FIG. 3 (b) shows a large number of rectangular frames partitioned by a portion where the entry field is indicated by a straight line (a field for entering the date and name) and a horizontal ruled line perpendicular to it. This is an example showing a document with a marked portion. For example, in the form of a product order form, a form with many frames for filling in the number and name of the product to be ordered is frequently used. It is known that a copy can be written at the same time. In this case, since the characters on the copy sheet are filled with the characters through the carbon paper, there is a high possibility that the sheets will be thin. If such a copy is copied, the characters become unclear. Therefore, as shown in FIG. 3B, a straight line composed of a group of pixels having a relatively low density as a predetermined density and an image in which a large number of frames are drawn also have a predetermined format (entry frame). It is judged.

  The frame partitioned by the ruled lines partitions a large outer rectangle in the vertical direction and the horizontal direction, the vertical partition is the same interval, and the horizontal partition is partitioned to different lengths. . Therefore, a plurality of the same rectangles are arranged in the vertical direction.

  FIG. 3C shows an example of a manuscript in which sentences, photographs, etc. are written on most of the paper surface and one rectangular frame is written. Thus, when the number of frames is small, it is determined that the paper is not a carbon paper document to be filled in using carbon paper or the like.

  Next, a method for detecting a straight line will be described with reference to FIG. Various methods such as Hough transformation have been proposed as a method for detecting a straight line formed in an image by image processing. Here, an outline of a method using a chain code will be described.

  The chain codes shown in FIG. 4B are divided into eight types on the plane, and codes up to “7” are assigned counterclockwise with the right lateral direction being “0”. This is because pixels are arranged at intersections of grids (hereinafter referred to as grid points) in which horizontal lines are drawn at equal intervals in the horizontal direction and in the vertical direction perpendicular to the horizontal direction. This is because adjacent pixels exist in any one of these eight directions.

  FIG. 4A is a diagram showing an example of an image, in which lattice points are indicated by small dots, pixels forming the outline of the image are indicated by black circles, and pixels inside the outline are indicated by white circles. In this straight line detection method, it is detected whether or not the contour of the image forms a straight line. Here, the grid point in the m-th row and the n-th column is expressed as (m, n).

  First, in this figure, as indicated by an arrow, when scanning is performed in the right direction from the upper left lattice point, black dots are present at the second row, third column lattice point (2, 3). Next, since a black circle also exists at the lattice point (2, 4) on the right side, the code is set to “0”. Similarly, since a black circle also exists at the right grid point (2, 5), the code “0” is set and connected to the previous code, and the chain code becomes “00”. Furthermore, since black circles also exist at the adjacent grid point (2, 6), the chain code is “000”. Next, it is the lower lattice point (3, 6) that has a black circle at the lattice point adjacent to this lattice point, and the code indicating the lower portion is “6”. Therefore, the chain code is “0006”.

  Since the black circles adjacent to the lattice point exist at the lattice point (4, 7), the direction of the lattice point is the lower right direction and the code is 7. Therefore, the chain code is “00067”.

  Hereinafter, similarly, a chain code corresponding to the contour is formed by sequentially arranging codes indicating the directions of adjacent black circles. In the case of FIG. 4A, “00067666652344222” is obtained.

  When the chain code is formed in this way, a portion where the same code is arranged next is detected, and when a predetermined number or more of the same code is arranged, it is a straight line having a predetermined length or more. Can be determined.

Further, by obtaining the coordinates of both ends of the detected straight line, it is possible to detect not only the length of the plurality of straight lines but also the position and direction of the straight lines in the document. Note that all the coordinates of the straight line can be obtained from the chain code. In the present embodiment, the main scanning direction of the document is described as the x axis and the sub scanning direction is described as the y axis. When the lengths of the plurality of straight lines are the same, for example, among the (x, y) coordinates at both ends of the plurality of straight lines, the x coordinates are common, and the y coordinates are different at equal intervals. If there are, it can be determined that a plurality of straight lines having the same length exist in the same direction at the same interval.
Furthermore, even if the x coordinate is common, if the y coordinate interval is an extremely small value, it is difficult to enter characters and the like. The coordinate information is valid. For example, when a plurality of straight lines having the same length are arranged in parallel as in the case of a barcode, the determination of the predetermined format as described above is made only with the length of the straight line, the length of the straight line of the barcode is If the condition is satisfied, it is determined to be in a predetermined format. However, not only the length but also the interval between the straight lines can be detected based on the coordinates, so that when the interval is extremely narrow, the predetermined format may not be determined.

  It is also possible to detect whether or not a plurality of detected straight lines are orthogonal to form a closed frame such as a rectangle. In this case as well, the coordinates of the straight line are used to detect whether or not there is a coordinate that intersects the main scanning direction and the sub-scanning direction for the detected straight line. For example, a frame is formed by the intersection of two straight lines parallel to the main scanning direction and two straight lines parallel to the sub-scanning direction. In this case, four intersections (coordinates) are detected. Assume that the intersection points are A, B, C, and D, and the coordinates are A = (x1, y1), B = (x2, y2), C = (x3, y3), and D = (x4, y4). If x1 and x2 are equal, x3 and x4 are equal, y1 and y4 are equal, and y2 and y3 are equal, it is determined that the frame has intersections A, B, C, and D as four corners. Can do.

  Furthermore, the area of the inside of the frame can be calculated by obtaining the lengths of the four straight lines forming the frame and performing the calculation. When the calculated area is an extremely small value, the frame itself is small, so it can be determined that the frame is not a frame for entering characters or the like.

  Next, the printing process executed by the CPU 21 will be described with reference to FIG. This process is described in the print processing program 22 a stored in the ROM 22. This process is executed when the user instructs to read a document on which an image is recorded and print it in monochrome. First, image data of a document is read by pre-scanning, and pixels with low density are detected by referring to the image data. If there is no problem in density, it can be output as it is. On the other hand, a pixel having a low density is detected, and whether or not the pixel is a carbon paper document is determined based on whether or not the pixel forms a straight line or a frame in the image. Next, the main scan is performed, and if it is determined that the original is a carbon paper original as a result of the previous determination, printing is performed with the image density increased, and if it is determined that the original is not a carbon paper original, the image is Printing is performed without changing the density of the image.

  A description will be given sequentially according to the flowchart. First, the paper image set by the user is read by the scanner unit 3, and the RGB value, which is the density value of each pixel, is temporarily stored in the image memory 23a (S1). In this pre-scanning, the resolution is made lower than usual, and the image of the entire surface of the document is stored in the image memory 23a. The normal resolution is, for example, 600 dpi, and the pre-scan resolution is, for example, about 100 dpi. By reducing the resolution, the amount of acquired image data is reduced, so that the storage capacity may be small.

  Next, the size of the document is detected based on the image data stored in the image memory 23a (S2). The document is a recording medium such as thick paper, and light irradiated from the light source is irregularly reflected and a shadow is formed at the edge of the document, so that the size of the document can be detected from the image data. The size of the document may be specified by the user by operating a switch on the operation panel.

  When the size of the document is detected, a predetermined length to be detected as a straight line is set according to the size of the document (S3). In the present invention, a straight line included in an image is detected, and when the length of the straight line is longer than a predetermined length, it is determined whether or not a predetermined format exists based on the straight line. This predetermined length varies depending on the size of the document. That is, the larger the size of the document, the longer the predetermined length. Therefore, for example, a predetermined length corresponding to the size of the document is stored in advance in the ROM 22 as a table, and the predetermined length corresponding to the size of the document is set by referring to the table. For example, the length stored in the ROM 22 is 50% or more with respect to the main scanning direction of the document. Moreover, it may be configured such that the user can change the setting with 50% as a default.

Next, it is determined from the RGB value of each pixel stored in the image memory 23a whether or not the density value of each pixel is within a predetermined range. A pixel that is not “0” is set to “0” (S4). Hereinafter, “1” or “0” set for this pixel is a pixel value.
This range of density values means that density is set in advance for each of the R value, G value, and B value in order to set a pixel value “1” for a pixel to be printed lightly when performing monochrome printing by performing a main scan. A range of values is set. Then, a pixel having a density value in which all of the R value, the G value, and the B value belong to a predetermined range is set to “1”. The values in these ranges are different values depending on the color of light irradiated on the original when scanning, the type of sensor, and the like. Note that a range of values for determining that the density is high may be determined, and it may be determined that the value is light outside the range.

  Next, based on the pixel value converted by the process of S4, it is determined whether or not there are a predetermined number or more of low density pixels (S5). In this determination, it is determined whether or not the number of pixels having a pixel value “1” or the ratio of the number to all the pixels is equal to or greater than a predetermined value.

  If it is determined that there are a predetermined number or more of pixels having a pixel value “1” (S5: Yes), it is detected whether the pixel converted to “1” forms a straight line (S6). As described above, this detection detects whether or not the pixels constituting the contour of the image form a straight line. When a straight line is detected, the length of the straight line is detected. Further, for the straight line whose detected length is equal to or longer than the predetermined length set by the process of S3, information on the straight line such as the coordinate position and the straight line direction is detected based on the chain code described in detail above, and the RAM 23 Are stored in sequence. Next, the number of straight lines having a predetermined length or more existing on the entire surface of the document is counted and stored in the straight line count memory 23b (S7).

  Next, it is determined whether or not the count value stored in the straight line count memory 23b is equal to or greater than a predetermined number M (for example, M is set to “5”) (S8). When the number of detected straight lines is equal to or greater than the predetermined number M (S8: Yes), there is a predetermined format in which a plurality of straight lines are printed in parallel as shown in FIG. In the actual scan, the density value of each pixel is changed so as to increase the density of the entire document, and is output to the printer unit 2 (S12).

  In the determination process of S8, when the number of straight lines is not greater than the predetermined number M (S8: No), it is determined whether or not a plurality of straight lines form a frame such as a rectangle (S9). Whether or not a plurality of straight lines form a frame is determined by detecting the intersection of the straight lines. When forming a frame as a result of the detection, the area inside the frame is further calculated, and the number of frames whose area is a predetermined value or more is counted and stored in the frame count memory 23c of the RAM 23 (S10).

  Next, it is determined whether or not the number of frames is equal to or greater than a predetermined number N (for example, N is set to “3”) (S11). When the number of frames is greater than or equal to the predetermined number N (S11: Yes), there is a predetermined format on which a plurality of frames are printed as shown in FIG. It is determined that the document is a document, and at the time of the main scan, the density value of each pixel is changed so that the density of the entire document becomes dark and output to the printer unit 2.

  On the other hand, when it is determined in the determination process of S5 that there are no more than a predetermined number of pixels with low density (S5: No), or when it is determined that a plurality of straight lines do not form a frame in the determination process of S9 (S9). : No), or if it is determined in S11 that the number of frames having a predetermined area or more does not exist more than the predetermined number N (S11: No), there is no problem in the density of the read image data, or the document Is not a carbon paper document including a predetermined format, the main scan is performed, and the image is output to the printer unit 2 without changing the density (S13).

  When the process of S12 or S13 is finished, printing is performed by the printer unit 2 (S14), and the printing process is finished.

  As described above, as described based on the embodiment, the acquired image data includes pixels with a predetermined range of density (pixels with low density), and the pixels form a plurality of straight lines, When the various conditions as described above are satisfied, it is determined that a predetermined format is formed.

  In particular, when there are a predetermined number or more of the straight lines and the lines are equally spaced or form a rectangular frame, it is determined that a predetermined format such as an entry field or an entry frame is included, It is determined that the manuscript is written with characters and the like on carbon paper.

Therefore, a document made of carbon paper or a document on which characters are written using carbon paper (carbon paper document) generally has a low image density as a result of copying. Carbon paper is often used for forms, application forms, purchase orders, and the like, and is characterized by a form in which a straight portion for entering a name, an address, etc., and a frame are printed in advance. In such a format, there are several straight lines having a predetermined length or more in the image. Therefore, the straight lines are detected from the read image data, and it is determined whether or not the predetermined format exists based on the straight lines. be able to. For this reason, when the read image data has a relatively low density and includes a predetermined format, it is determined to be a carbon paper document, and an image based on the image data is obtained without the user instructing the density adjustment. The density at the time of output is automatically changed appropriately. Therefore, it is possible to perform an appropriate density adjustment process according to the type of image.
Also, a carbon paper document is usually formed with a plurality of straight lines having a predetermined length indicating an entry field, and when the number of straight lines is small, it can be determined that a predetermined format does not exist. Therefore, it is possible to determine whether or not a predetermined format exists more accurately based on the number of straight lines.
Further, in a carbon paper document, a frame indicating an entry field is usually formed by a plurality of straight lines having a predetermined length. Therefore, it is possible to determine whether or not a predetermined format is included by detecting the frame.
In addition, in a carbon paper document, a frame indicating an entry column usually has a predetermined area. Therefore, it is possible to determine whether or not a predetermined format is included by detecting the area of the frame.
Further, a carbon paper document is usually formed with a frame indicating an entry field, the frame has a predetermined area, and a plurality of frames having the predetermined area are formed. Therefore, it is possible to determine whether or not a predetermined format is included by detecting the number of frames having a predetermined area.
When it is determined that a predetermined format is formed by a pixel group whose density value is determined to be a thin pixel within a predetermined range based on the plurality of conditions as described above, the read original is It is recognized as a manuscript in which characters and the like are entered on the paper on which the above format is printed via carbon paper. Therefore, even if the entered character is thin, it is automatically converted into a dark color and output during copying, so that it is possible to prevent image output that cannot be identified. On the other hand, in the case of a natural image or the like that does not include a straight line or a frame, it is not detected as a predetermined format, and the image data is not converted to be dark, so that it is possible to prevent image quality deterioration.

  The reading means described in the claims corresponds to the processes of S1, S12 and S13 in the flowchart shown in FIG. 5, and the density judging means and the density judging step are the processes of S4 and S5 in the flowchart shown in FIG. Is applicable. The straight line detection means and the straight line detection step correspond to the process of S6 of the flowchart shown in FIG. 5, and the format determination means and the format determination step correspond to the processes of S5, S8, S9 and S11 of the flowchart shown in FIG. To do. The output means and the output step correspond to the processes of S12 and S13 of the flowchart shown in FIG. 5, and the document size detection means corresponds to the process of S2 of the flowchart shown in FIG. The area calculating means corresponds to the process of S10 of the flowchart shown in FIG. 5, the pre-scan means corresponds to the process of S1 of the flowchart shown in FIG. 5, and this scanning means corresponds to the process of the flowchart shown in FIG. The process of S12 and S13 corresponds.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications can be easily made without departing from the spirit of the present invention. It can be done.

  For example, in the above embodiment, the processing in the multi-function peripheral device has been described. However, the processing may be performed in a single-function device such as a printer or a facsimile machine.

  In the above embodiment, the image data read by the scanner unit 3 is processed. However, image data formed by another device is input, and the input image data is processed. Good.

  Conversely, image data read by a scanner device having only a function of reading and outputting an image of a document is input, an image processing program is installed in a personal computer, and the processing of the present invention is performed. May be output.

  In the above-described embodiment, the pre-scan reads a color image. However, it may be a monochrome image read regardless of whether the document is color or monochrome. In this case, the luminance value of the monochrome image is stored in the image memory 23a, and pixels with low density are detected based on the luminance value.

  In the above embodiment, a predetermined format exists when there are a predetermined number M or more of straight lines having a predetermined length. However, the number of straight lines having the same direction is detected, and the number of straight lines is detected. A predetermined format may be present when the number is greater than or equal to the predetermined number. In this case, when the number of straight lines having the same direction and the same straight line length is detected and the number is equal to or larger than a predetermined number, a predetermined format may be present. At that time, the interval between a plurality of straight lines is detected, and the number of straight lines described at equal intervals is detected. If the number is equal to or greater than a predetermined number, a predetermined format is assumed to exist. Also good.

  In the above embodiment, the predetermined format exists when there are N or more frames having a predetermined area or more. However, when the frame is rectangular, the direction of the long side is the same direction. When the number of frames is detected and the number is equal to or greater than a predetermined number, a predetermined format may be present. In this case, the number of frames having the same long side direction and the same frame area is detected, and when the number is equal to or larger than a predetermined number, a predetermined format may exist. Good.

  Furthermore, in the above-described embodiment, a case has been described in which the density values of the three RGB colors read by the color sensor are acquired during pre-scanning. However, depending on the scanner specifications, for example, a single-color sensor (such as “G” only) may be used. It is also possible to perform reading. In this case, a pixel having a low density is selected by using only “G” from among the preset density value ranges of R, G, and B values. You may make it judge.

1 is a perspective view showing an external appearance of a multifunction peripheral device having an image processing apparatus according to an embodiment of the present invention. It is a block diagram which shows the electrical constitution of a multifunction peripheral device A plurality of images are shown, (a) is an image in which a plurality of straight lines are drawn, (b) is an image in which a large number of frames are drawn by a plurality of straight lines, (c) is a small frame together with a photograph, etc. Is an image in which is drawn. It is a figure for demonstrating the method to detect a straight line, (a) shows the example of an image, (b) is a figure which shows a chain code | cord | chord. It is a flowchart which shows the printing process performed by CPU.

Explanation of symbols

1 Multifunctional peripheral device (MFP)
2 Printer section (output means)
3 Scanner section (reading means)
21 CPU
22 ROM
23
RAM
23a Image memory (image storage means)
23b Straight line count memory (straight line number counting means)
23c Frame count memory (frame number counting means)

Claims (9)

Reading means for reading an image recorded on a document and acquiring image data;
Density determining means for determining whether or not the density value of each pixel constituting the image data acquired by the reading means is included in a predetermined range of values;
A straight line detecting means for detecting a straight line having a predetermined length or more, which is formed by a pixel group whose density value is determined to be included in a predetermined range by the density value determining means;
Format judging means for judging whether or not there is a predetermined format formed by straight lines in the image, based on the straight line information detected by the straight line detecting means;
If the format determining means determines that a predetermined format exists in the image, the density value of each pixel constituting the image data read by the reading means is changed so as to increase the density and output. ,
When the format determining means determines that the predetermined format does not exist in the image, the density value of each pixel constituting the image data read by the reading means is not changed so as to increase the density. An image processing apparatus comprising output means for outputting. The image data is color image data,
The density values of the pixels are an R value, a G value, and a B value,
2. The image according to claim 1, wherein the density determination unit determines a pixel having a low density by determining whether or not the density values of the R value, the G value, and the B value are within a predetermined range. Processing equipment. A document size detection unit that detects a size of a document on which an image read by the reading unit is recorded;
The image processing apparatus according to claim 1, wherein the predetermined length is set according to a size of a document detected by the document size detecting unit. Straight line number counting means for counting the number of straight lines of a predetermined length or longer detected by the straight line detection means,
4. The format determination unit according to claim 1, wherein the format determination unit determines whether or not the read image of the document includes a predetermined format based on the number of straight lines detected by the straight line number detection unit. The image processing apparatus according to any one of the above. A frame detection unit for detecting a frame formed by the straight line detected by the straight line detection unit;
4. The format determination unit according to any one of claims 1 to 3, wherein the format determination unit determines whether an image of a document read based on a frame detected by the frame detection unit includes a predetermined format. The image processing apparatus described. An area calculating means for obtaining an area inside the frame detected by the frame detecting means;
6. The format determination unit according to claim 5, wherein the format determination unit determines whether or not the read image of the document includes a predetermined format based on an area inside the frame calculated by the area calculation unit. Image processing device. A frame number counting means for counting the number of frames whose inner area calculated by the area calculating means is equal to or larger than a predetermined area;
7. The image according to claim 6, wherein the format determining unit determines whether or not the read image of the document includes a predetermined format based on the number of frames counted by the frame number counting unit. Processing equipment. The reading means includes pre-scanning means for acquiring image data of an image at a predetermined resolution by color reading, and main scanning means for acquiring image data of the image at a resolution higher than the predetermined resolution by monochrome reading,
The density determination unit determines whether or not the density value of each pixel constituting the image data acquired by the pre-scan unit is included in a predetermined range of values,
When the format determining means determines that a predetermined format exists in the image, the output means increases the density value of each pixel constituting the image data acquired by the main scanning means. When the format determining means determines that the predetermined format does not exist in the image, the density value of each pixel constituting the image data acquired by the main scanning means is The image processing apparatus according to claim 1, wherein the image processing apparatus outputs the image without changing it so as to be dark. An image processing program that is executed in a computer that inputs image data acquired by a reading device that reads an image and processes the image data,
A density determination step for determining whether a density value of each pixel constituting the input image data is included in a predetermined range of values;
A straight line detecting step for detecting a straight line having a predetermined length or more, which is formed by the pixel group determined to be included in the predetermined range by the density value determining step;
A format determination step for determining whether or not there is a predetermined format formed by a straight line in the image based on the straight line information detected by the straight line detection step;
If it is determined by the format determining step that a predetermined format exists in the image, the density value of each pixel constituting the image data is changed and output so that the density is high,
An output step for outputting, without changing the density value of each pixel constituting the image data so that the density becomes high, when the format judging means judges that the predetermined format does not exist in the image; An image processing program comprising:

Images