JP6618307B2 - Image processing apparatus, image forming apparatus, and resolution determination method - Google Patents

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, and a resolution determination method for determining an output resolution related to output processing of document image data.

  In recent years, digital image processing systems have made remarkable progress, and the construction of digital image processing technology is progressing. For example, in a field such as a copying machine using an electrophotographic method or an ink jet method, a multi-function printer (MFP), a document manuscript is read by a scanner and stored as a document file which is electronic data. Stored document files are managed. It is also possible to compress the document file and send it by e-mail.

  In general, since an image read by a scanner (hereinafter referred to as a scanned image) has a large file size, it is necessary for the user to manually set the resolution according to the purpose of storing or transmitting the scanned image. However, in order for the user to set appropriately, it is required to be familiar with the setting items. Therefore, automatic setting of an appropriate scan resolution is desired regardless of the level of the user.

  For example, in the image forming apparatus according to Patent Document 1, a character region is extracted from the read image data, the character size included in the extracted character region is analyzed, and the minimum character size is detected from the analysis result, An appropriate resolution is determined based on the detected minimum character size. Image data relating to a predetermined resolution at the time of reading is converted into image data relating to the determined resolution and output.

  The image forming apparatus according to Patent Document 1 extracts a circumscribed rectangle of a black pixel connected component as a character size, integrates the circumscribed rectangles that overlap perpendicularly to the character string direction, and generates a basic rectangle. A height histogram is created, and with this, a long character, a true character, and a plain character are discriminated, a character width / height is calculated, a character size is determined, and a minimum character size is detected.

JP 2009-296533 A

  However, even when outputting at the same resolution, for example, whether or not kanji is used in the document, whether the document is output in color or gray scale (multi-valued data), monochrome (monochrome binary) The visibility of the user with respect to the characters in the output image varies greatly depending on whether or not the data is output. Therefore, in consideration of this, the resolution related to the output should be determined. However, the image forming apparatus according to Patent Document 1 is not considered at all.

  The present invention has been made in view of such circumstances, and an object of the present invention is to determine an output resolution related to output processing of image data of a document, or an output setting related to an output or a document related to the document. An object of the present invention is to provide an image processing apparatus, an image forming apparatus, and a resolution determination method capable of determining a resolution for output in consideration of document information.

  An image processing apparatus according to the present invention, in an image processing apparatus for determining an output resolution related to an output process of image data of a document, a specific information generating unit that generates character specifying information for specifying a character candidate included in the image data; A storage that stores an output setting relating to output, or an acquisition unit that obtains original information relating to the original, and a table that associates the character specifying information and the output resolution in accordance with the output setting or the original information. And a search unit that searches the table for output resolution corresponding to the character identification information generated by the specific information generation unit in accordance with the output setting or document information acquired by the acquisition unit. And

  When a plurality of output resolutions are searched, the image processing apparatus according to the present invention determines any of the searched output resolutions based on the number of character candidates related to the character specifying information corresponding to each of the searched output resolutions. A selection unit for selecting is provided.

  In the image processing apparatus according to the present invention, the output setting includes either a binary output or a multi-value output, and the table is a binary output in the case of a multi-value output. In this case, the output resolution is set to be lower.

  In the image processing apparatus according to the present invention, the output setting includes a setting of either a priority of a data capacity (file size) to be output or a priority of an image quality related to output, and the table includes a data capacity to output When priority is given to the size of (file size), the output resolution is set to be lower than when priority is given to the output image quality.

  In the image processing apparatus according to the present invention, the output setting includes a setting of a compression rate related to output, and the table is set such that the output resolution is lower as the compression rate is lower. And

  In the image processing apparatus according to the present invention, the document information includes information related to a language used, and the table is set such that the output resolution is lower for a language with higher visibility. .

  In the image processing apparatus according to the present invention, the selection unit sequentially adds the number of character candidates corresponding to each searched output resolution from the searched highest output resolution, and adds the added value and all of the character candidates. When the ratio to the number is equal to or greater than a predetermined threshold, the searched output resolution related to the character candidate added last is selected.

In the image processing device according to the present invention, the image data includes a character string including the character candidate, and the search unit searches the output resolution based on character specifying information related to the character candidate of the character string. It is characterized by that.

  An image forming apparatus according to the present invention includes the image processing apparatus according to any one of the above-described inventions, and forms an image on a sheet-like recording medium based on image data processed by the image processing apparatus. It is characterized by that.

  A resolution determination method according to the present invention is a resolution determination method for determining an output resolution related to an output process in an image processing apparatus that performs an output process of image data of a document, and a character specification that specifies a character candidate included in the image data Information is generated, output settings related to output or document information related to the document is acquired, and acquired based on a table in which the character specifying information and output resolution are associated with each other according to the output setting or the document information. The output resolution corresponding to the generated character specifying information is searched according to the output setting or document information.

  According to the present invention, when determining the output resolution related to the output processing of the image data of the document, the output resolution is more accurately determined by considering the output setting related to the output or the document information related to the document. be able to.

1 is a block diagram illustrating an example of a configuration of an image forming apparatus according to a first embodiment. 1 is a block diagram illustrating an example of a configuration of an image forming apparatus according to a first embodiment. FIG. 6 is a block diagram illustrating another example of the configuration of the image forming apparatus according to the first embodiment. 3 is a block diagram illustrating an example of a configuration of a processing parameter determination unit according to the first embodiment. FIG. 4 is a flowchart illustrating an example of a processing procedure of an edge detection unit of the image forming apparatus according to the first embodiment. 6 is a schematic diagram illustrating an example of edge detection processing by an edge detection unit of the image forming apparatus according to Embodiment 1. FIG. 4 is a flowchart illustrating an example of a processing procedure of a character rectangle extraction unit of the image forming apparatus according to the first embodiment. FIG. 6 is a schematic diagram illustrating an example of a character rectangle extraction process by a character rectangle extraction unit of the image forming apparatus according to the first embodiment. 4 is a flowchart illustrating an example of a processing procedure of a character string extraction unit of the image forming apparatus according to the first embodiment. The image forming apparatus of Embodiment 1 is a schematic diagram illustrating an example of character string extraction processing by a character string extraction unit. In Embodiment 1, it is a functional block diagram which shows the principal part structure of the resolution determination part. 4 is a table conceptually illustrating an example of an output resolution table stored in a storage unit of the image forming apparatus according to the first embodiment. 3 is a flowchart illustrating an example of a processing procedure of a resolution determination unit of the image forming apparatus according to the first embodiment. It is an illustration figure which shows an example of character string specific information and character specific information. It is a graph which shows the relationship between the detected output resolution and the number of counted character candidates (character rectangle). 14 is a table conceptually illustrating another example of an output resolution table stored in a storage unit of the image forming apparatus according to the third embodiment. FIG. 10 is a block diagram illustrating an example of a configuration of an image reading apparatus according to a fourth embodiment. FIG. 10 is a block diagram illustrating an example of a configuration of an image reading apparatus according to a fourth embodiment. 10 is a schematic diagram illustrating an example of a resolution setting method according to Embodiments 1 to 4. FIG. FIG. 10 is a schematic diagram illustrating an input screen that receives an input of the output setting or the document information from a user in the image forming apparatus according to the first embodiment and the image reading apparatus according to the fourth embodiment.

(Embodiment 1)
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. 1 and 2 are block diagrams illustrating an example of the configuration of the image forming apparatus 100 according to the first embodiment. FIG. 1 shows signal processing when the read color image data is output from the color image output device 2, and FIG. 2 shows signal processing when the read color image data is transmitted from the transmission device 3. In the following description, the image forming apparatus 100 as an image processing system will be described.

  The image forming apparatus 100 is a digital multifunction machine having a color copy function, a color scanner function, and the like. The image forming apparatus 100 includes a color image input device 1 as an image input device that optically reads a color image from a document.

  Connected to the color image input device 1 is a color image processing device 50 as an image processing device that generates image data of a read color image and a compressed file.

  The color image processing device 50 includes a color image output device 2 as an image output device that outputs a color image based on the image data generated by the color image processing device 50, and a compressed file generated by the color image processing device 50 as an external device. Is connected to a transmission device 3 as an image output device.

  That is, the image forming apparatus 100 includes a color image input device 1, a color image processing device 50, a color image output device 2, a transmission device 3, and the like. An operation panel 4 is connected to the color image input device 1, the color image processing device 50, the color image output device 2, and the transmission device 3.

  The operation panel 4 includes a setting button for the user to set the operation mode of the image forming apparatus 100, an operation unit such as a numeric keypad, a display unit including a liquid crystal display and the like (all not shown). Various processes executed by the image forming apparatus 100 are controlled by a CPU (Central Processing Unit) (not shown). The CPU of the image forming apparatus 100 performs data communication with a computer and other digital multi-function peripherals connected to the network via a network card and a LAN cable (not shown).

  Hereinafter, each part of the image forming apparatus 100 will be described in detail.

  The color image input device 1 is composed of, for example, a color scanner having a CCD (Charge Coupled Device). The color image input apparatus 1 reads a reflected light image from an original as an 8-bit, 10-bit RGB (R: red, G: green, B: blue) analog signal using a CCD and supplies the image to the color image processing apparatus 50. Output. That is, the image data read from the document by the color image input apparatus 1 is multivalued. In the following, processing when multi-value input image data is output as multi-value (color or gray scale) image data will be described.

  The color image processing device 50 performs an A / D conversion unit 11, a shading correction unit 12, a document type determination unit 13, an input tone correction unit 14, and an RGB analog signal input from the color image input device 1. Image data composed of RGB digital signals (hereinafter referred to as RGB signals) is generated by executing image processing to be described later in the region separation processing unit 15.

  In addition, the color image processing device 50 applies a color correction unit 16, a black generation and under color removal unit 18, a spatial filter processing unit 19, an output tone correction unit 21, and a floor to the RGB signals output from the region separation processing unit 15. The tone reproduction processing unit 22 executes image processing to be described later, thereby generating image data composed of digital signals of CMYK (C: cyan, M: magenta, Y: yellow, K: black) as a stream. Output to the color image output device 2. The image data may be temporarily stored in the storage unit 24 before being output to the color image output device 2.

  The storage unit 24 is a non-volatile storage device (for example, a hard disk). Further, the storage unit 24 stores an output resolution table to be described later.

  The color image output device 2 forms a color image on a recording sheet (for example, recording paper) based on the image data input from the color image processing device 50 by a method such as thermal transfer, electrophotography, or inkjet. Output.

  The color image processing apparatus 50 also includes a color correction unit 16, a spatial filter processing unit 19, a resolution conversion processing unit 20, an output tone correction unit 21, and a compression processing unit for the RGB signals output from the region separation processing unit 15. By executing image processing to be described later at 23, compressed image data generated by compressing output image data composed of RGB digital signals or grayscale image data is generated and output to the transmission device 3.

  In the present embodiment, when the resolution conversion processing unit 20 performs the resolution conversion process, the processing parameter determination unit 17 determines the output resolution (resolution) to be converted as necessary, and determines the determined resolution. By outputting to the resolution conversion processing unit 20, it is possible to convert the input image (image data) to a desired output resolution.

  Note that the output image data or compressed data obtained by compressing the output image data may be temporarily stored in the storage unit 24 before being output to the transmission device.

  As shown in FIG. 1, when the color image data read by the color image input device 1 is output from the color image output device 2, the resolution conversion processing unit 20 and the compression processing unit 23 do not operate. As shown in FIG. 2, when the color image data read by the color image input device 1 is transmitted from the transmission device 3, the black generation and under color removal unit 18 and the gradation reproduction processing unit 22 do not operate.

  The transmission device 3 can be connected to a communication network such as a public network (not shown), a LAN (Local Area Network), or the Internet, and transmits a compressed file to the outside via the communication network by a communication method such as facsimile or e-mail. To do. For example, when the scan to e-mail mode is selected on the operation panel 4, the compressed file is attached to the e-mail by a transmission device using a network card, a modem, etc., and transmitted to the set transmission destination. The

  When performing facsimile transmission, the CPU of the image forming apparatus 100 performs a communication procedure with the other party in the transmission apparatus 3 using a modem, and compression is performed when a transmission possible state is secured. After performing necessary processing such as changing the compression format on the file, the file is sequentially transmitted to the other party via a communication line. When receiving a facsimile, the CPU of the image forming apparatus 100 receives a compressed file transmitted from the other party while performing a communication procedure at the transmitting apparatus 3 and outputs the compressed file to the color image processing apparatus 50.

  In the color image processing apparatus 50, the received compressed file is decompressed by an unillustrated decompression processing unit. The image data obtained by decompressing the compressed file is subjected to rotation processing and / or resolution conversion processing by a processing unit (not shown) as necessary, and the output gradation correction unit 21 outputs the output level. Tone correction is performed, and the gradation reproduction processing unit 22 performs gradation reproduction processing. The image data that has undergone various types of image processing is output to the color image output device 2, and an output image is formed on the recording sheet by the color image output device 2.

  Hereinafter, image processing in the color image processing apparatus 50 will be described in detail. First, a process when image data input from the color image input device 1 is output to the color image output device 2 will be described.

  The A / D conversion unit 11 receives an RGB analog signal input from the color image input device 1, converts the RGB analog signal into an RGB digital signal (that is, an RGB signal), and converts the converted RGB signal into a shading correction unit. 12 is output.

  The shading correction unit 12 performs processing for removing various distortions generated in the illumination system, the imaging system, and the imaging system of the color image input apparatus 1 on the RGB signal input from the A / D conversion unit 11. The shading correction unit 12 then outputs the RGB signal from which the distortion has been removed to the document type determination unit 13.

  The document type discrimination unit 13 converts the RGB reflectance signal input from the shading correction unit 12 into a density signal indicating the density of each RGB color, and discriminates the mode of the document such as a character, a printed photograph, or a photographic paper photograph. Document type determination processing is executed. When the user manually sets the document type determination process using the operation panel 4, the document type determination unit 13 outputs the RGB signal input from the shading correction unit 12 to the input tone correction unit 14 at the subsequent stage as it is. The processing result of the document type determination processing is reflected in the subsequent image processing.

  The input tone correction unit 14 performs image quality adjustment processing such as color balance adjustment, background density removal, and contrast adjustment on the RGB signals. Next, the input tone correction unit 14 outputs the processed RGB signal to the region separation processing unit 15.

  The region separation processing unit 15 separates each pixel in the image represented by the RGB signal input from the input tone correction unit 14 into one of a character region, a dot region, and a photo region. Further, the region separation processing unit 15 generates a region identification signal indicating which region each pixel belongs to based on the separation result, and generates a black generation and under color removal unit 18, a spatial filter processing unit 19, and a gradation reproduction processing unit. 22 and the processing parameter determination unit 17.

  The color correction unit 16 converts the RGB signal input from the region separation processing unit 15 into a CMY digital signal (hereinafter referred to as “CMY signal”), and CMY colors including unnecessary absorption components for realizing faithful color reproduction. Processing for removing color turbidity based on the spectral characteristics of the material from the CMY signal is performed. Then, the color correction unit 16 outputs the CMY signal after the color correction to the black generation and under color removal unit 18.

  Based on the CMY signal input from the color correction unit 16, the black generation and under color removal unit 18 subtracts the black generation processing for generating a black (K) signal from the CMY signal and the K signal obtained by black generation from the CMY signal. To generate a new CMY signal. As a result, the CMY3 color digital signals are converted into CMYK 4 color digital signals (hereinafter referred to as CMYK signals). Then, the black generation and under color removal unit 18 outputs the CMYK signal obtained by converting the CMY signal to the spatial filter processing unit 19.

  As an example of the black generation process, a method of generating black by skeleton black is generally used. In this method, the input / output characteristic of the skeleton curve is y = f (x), the input data is C, M, Y, the output data is C ′, M ′, Y ′, K ′, UCR (Under When the color removal rate is α (0 <α <1), the black generation and under color removal processing is expressed by the following equations (1) to (4).

Formula (1): K ′ = f (min (C, M, Y))
Formula (2): C ′ = C−αK ′
Formula (3): M ′ = M−αK ′
Formula (4): Y ′ = Y−αK ′

  Here, the UCR rate α (0 <α <1) indicates how much CMY is reduced by replacing the portion where CMY overlaps with K. Equation (1) indicates that the K signal is generated in accordance with the smallest signal strength among the signal strengths of CMY.

  The spatial filter processing unit 19 performs spatial filter processing with a digital filter on the image data of the CMYK signal input from the black generation and under color removal unit 18 based on the region identification signal input from the region separation processing unit 15. By correcting the spatial frequency characteristics, image blurring or graininess degradation is improved.

  For example, for a region separated into characters by the region separation processing unit 15, the spatial filter processing unit 19 uses a filter with a large amount of high-frequency component enhancement in order to improve character reproducibility. To do. Further, the spatial filter processing unit 19 performs low-pass filter processing for removing the input halftone dot component on the region separated into halftone dots by the region separation processing unit 15.

  The spatial filter processing unit 19 outputs the processed CMYK signal to the output tone correction unit 21.

  The output tone correction unit 21 performs output tone correction processing on the CMYK signal input from the spatial filter processing unit 19 based on the halftone dot area ratio that is a characteristic of the color image output device 2, and outputs tone correction. The processed CMYK signal is output to the gradation reproduction processing unit 22.

  The gradation reproduction processing unit 22 performs halftone processing corresponding to the region on the CMYK signal input from the output gradation correction unit 21 based on the region identification signal input from the region separation processing unit 15. For example, for a region separated into characters by the region separation processing unit 15, the gradation reproduction processing unit 22 performs binarization or multi-value conversion using a high-resolution screen suitable for reproducing high-frequency components. Perform processing. In addition, for a region separated into halftone dots by the region separation processing unit 15, the gradation reproduction processing unit 22 performs binarization or multi-value processing on the screen with an emphasis on gradation reproducibility. .

  The gradation reproduction processing unit 22 outputs the processed image data to the color image output device 2. When the image data input from the color image input device 1 is output to the color image output device 2, the processing parameter determination unit 17, the resolution conversion processing unit 20, and the compression processing unit 23 do not operate. The resolution conversion processing unit 20 and the compression processing unit 23 output the input CMYK signals as they are to the subsequent processing unit.

  Next, processing when image data input from the color image input device 1 is output to the transmission device 3 will be described. The processing from the A / D conversion unit 11 to the region separation processing unit 15 is the same as the processing when the image data input from the color image input device 1 is output to the color image output device 2, and thus description thereof is omitted.

  The region separation processing unit 15 outputs the RGB signal input from the input tone correction unit 14 to the subsequent color correction unit 16 and the processing parameter determination unit 17 as they are.

  When the scan function is selected in the automatic setting mode on the operation panel 4, the processing parameter determination unit 17 determines an output resolution for converting the image data into an optimum output resolution by the resolution conversion processing unit 20.

  The color correction unit 16 converts the RGB signal input from the region separation processing unit 15 into, for example, R′G′B ′ image data (for example, sRGB data) suitable for display characteristics of a display device that is widely used. Convert.

  Similarly, the spatial filter processing unit 19 applies spatial filter processing by a digital filter to the R′G′B ′ signal input from the color correction unit 16 based on the region identification signal input from the region separation processing unit 15. And correcting the spatial frequency characteristics to improve image blurring or graininess degradation. The spatial filter processing unit 19 outputs the processed R′G′B ′ signal to the resolution conversion processing unit 20.

  The resolution conversion processing unit 20 performs resolution conversion processing so that the image data has a desired output resolution determined by the processing parameter determination unit 17. For example, in a simple example, when the output resolution determined by the processing parameter determination unit 17 is 300 × 300 dpi with image data having a scanner input resolution of 600 × 300 dpi, the resolution conversion processing unit 20 By calculating an average value for every two pixels and using it as an output value, resolution conversion from 600 × 300 dpi to 300 × 300 dpi is performed.

  The output gradation correction unit 21 outputs the output level so that the background of the fog or highlight disappears or becomes thinner as necessary with respect to the R′G′B ′ signal input from the resolution conversion processing unit 20. The tone correction is performed, and the R′G′B ′ signal after the output tone correction processing is output to the compression processing unit 23.

  The compression processing unit 23 has a function as a compression unit, and performs compression processing such as JPEG on the image data including the R′G′B ′ signal according to the setting of the file format of the operation panel 4 as necessary. The compressed data is generated and output to the transmission device 3. Note that the compressed image data may be stored in a storage medium such as a USB memory or a hard disk, instead of being configured to transmit the image data to the transmission device 3.

  When the image data input from the color image input device 1 is output to the transmission device 3, the black generation and under color removal unit 18 and the gradation reproduction processing unit 22 do not operate. The black generation and under color removal unit 18 and the gradation reproduction processing unit 22 output the input R′G′B ′ signal as it is to the subsequent processing unit.

  Next, processing when multi-valued input image data is output in binary will be described with reference to FIG. FIG. 3 is a block diagram illustrating another example of the configuration of the image forming apparatus 100 according to the first embodiment. The processing from the A / D conversion unit 11 to the resolution conversion processing unit 20 is the same as the processing when multi-valued input image data is output as multi-value, and thus the description thereof is omitted.

  The output tone correction unit 21 converts the R′G′B ′ signal input from the resolution conversion processing unit 20 into K image data (a value indicating gray shades). This conversion is performed by using a predetermined matrix coefficient or the following equation.

Luminance value (value of K image data) = 0.299r + 0.587 g + 0.114b
Here, r is the value (pixel value) of red image data, g is the value of green image data, and b is the value of blue image data.

  The output tone correction unit 21 also performs binarization processing on the K image data and outputs the result to the compression processing unit 23 via the halftone generation unit 25. The threshold value for binarization is set to 128 when the image data is 8 bits. Alternatively, an average value of a pixel block composed of a plurality of pixels (for example, 3 × 3 pixels) may be obtained as a threshold value, and the target pixel of the block may be binarized. However, at this time, the halftone generation unit 25 does not perform any operation and outputs the input K signal as it is to the subsequent processing unit.

  The compression processing unit 23 performs compression processing on the K image data using a method such as MMR, generates compressed data, and outputs the compressed data to the transmission device 3.

  Next, the processing parameter determination unit 17 will be described in detail. FIG. 4 is a block diagram illustrating an example of the configuration of the processing parameter determination unit 17 according to the first embodiment. The processing parameter determination unit 17 includes an edge detection unit 171, a character rectangle extraction unit 172, a character string extraction unit 173, a resolution determination unit 174, and the like. The processing parameter determination unit 17 performs edge detection on the input RGB signal by the edge detection unit 171, extracts a character rectangle by the character rectangle extraction unit 172 based on the detected character edge, and extracts the character string extraction unit 173. Then, the character string is extracted based on the extracted character rectangle, and the resolution determination unit 174 determines the output resolution from the character string or the character rectangle. The character rectangle extraction unit 172 includes a specific information generation unit 172a.

  FIG. 5 is a flowchart illustrating an example of a processing procedure of the edge detection unit 171. As shown in FIG. 5, the edge detection unit 171 performs edge detection on the input RGB signal using an edge detection filter such as Sobel or Laplacian (step S11). The edge detection unit 171 performs character edge expansion processing (expansion processing) on the detected edge (step S12), extracts character edge candidates, and ends the processing.

  FIG. 6 (FIGS. 6A to 6E) is a schematic diagram illustrating an example of edge detection processing by the edge detection unit 171. FIG. 6A shows a part (10 × 10 pixels) of the G signal of the RGB image data. The numerical value in each frame is a pixel value. Although only the process for the G signal will be described here, the same process is performed for the R signal or the B signal. FIG. 6B shows a filter for edge detection. As the edge detection filter, for example, a Laplacian filter can be used as shown in FIG. 6B. Note that the edge detection filter is not limited to the example of FIG. 6B.

  FIG. 6C shows the result of filtering the 8 × 8 pixels surrounded by the thick frame in FIG. 6A with the filter shown in FIG. 6B. FIG. 6D shows an example in which only pixels having a pixel value of 100 or more are extracted as edge pixels (value is set to 1) and pixels having a pixel value of less than 100 are set to 0 with respect to the example of FIG. 6C. That is, when such processing is performed on the thick frame (8 × 8 pixels) in FIG. 6A, the result shown in FIG. 6D is obtained.

  FIG. 6E shows the result of character edge expansion (expansion processing) performed on the example (thick frame portion) in FIG. 6D. The dilation processing is performed by setting the value of the target pixel to 1 when the target pixel is 0 and there are edge pixels (pixels having a value of 1) in two or more of the eight neighboring pixels. . Let the example of FIG. 6E be a character edge candidate.

  As described above, by performing dilation processing after edge detection, as shown in FIG. 6, as a result of performing threshold processing on the filter processing result, pixels that are originally edges but are not determined to be edges are detected. In some cases, such pixels can be corrected and edges can be detected with high accuracy. Moreover, the connection of the pixels constituting the character can be improved.

  FIG. 7 is a flowchart illustrating an example of a processing procedure of the character rectangle extraction unit 172. The character rectangle extraction unit 172 (specific information generation unit 172a) generates character specification information (also referred to as character rectangle information) that specifies character candidates (also referred to as character rectangles) included in the image. Character candidates can be specified for each character. The character specifying information (character rectangle information) is position information for specifying a character candidate (character rectangle). For example, the upper left and lower right coordinate information of the character rectangle, the horizontal dimension (width) of the character rectangle, and Including vertical dimensions (height).

  More specifically, as shown in FIG. 7, the character rectangle extraction unit 172 performs a labeling process on the character edge candidates (for example, the example of FIG. 6E) output by the edge detection unit 171 (step S21). , Character rectangles (also referred to as character candidates and character rectangle regions) are extracted.

  After extracting the character rectangle, the character rectangle extracting unit 172 compares each extracted character rectangle with a nearby character rectangle size. As a result, the character rectangle extraction unit 172 removes the character rectangle whose size difference is larger than the predetermined value and the character rectangle similar to the vicinity does not exist as a non-character rectangle (step S22) and remains. The process is terminated using the character rectangle as character rectangle information.

  FIG. 8 (FIGS. 8A to 8E) is a schematic diagram showing an example of character rectangle extraction processing by the character rectangle extraction unit 172. FIG. FIG. 8A is an example of the edge detection result (character edge candidate) extracted by the edge detection unit 171. 8A and 6E show character edge candidates, but the example of FIG. 8A and the example of FIG. 6E are different for convenience.

  First, the character rectangle extraction unit 172 performs a labeling process on the edge detection result (character edge candidate) extracted by the edge detection unit 171. FIG. 8B shows a target pixel and a reference pixel when performing a labeling process. If the pixel indicated by * in FIG. 8B is the target pixel, the initial label of the target pixel is determined with reference to the labeling values of the four reference pixels (indicated by symbols a, b, c, and d) in the vicinity of the target pixel. . Specifically, when there is no pixel labeled with four reference pixels, a new label value is assigned to the target pixel. Further, when a plurality of label values exist in the four reference pixels, the minimum label value among them is given to the target pixel. FIG. 8C shows a result of adding an initial label to the edge detection result (character edge candidate) illustrated in FIG. 8A.

  Further, when there are a plurality of label values in the eight pixels around the target pixel to which the label value is assigned, the minimum label value among the initial label to which the target pixel is given and the label value of the eight pixels around the target pixel Is used as a correction label. FIG. 8D is an example showing the association between the initial label and the correction label. That is, in FIG. 8D, when an initial label is assigned to the target pixel, when there are a plurality of labels in the eight pixels around the target pixel, the label other than the minimum label value (initial label assigned to the target pixel) is included. Is associated with the minimum label value (initial label).

  FIG. 8D shows that, for example, label 3 (initial label 3) is associated with label 1 (correction label 1). In addition, label 6 (initial label 6) is related to label 5 (corrected label 5) at the initial association stage, but it is known that label 5 is related to label 4, Eventually, label 6 (initial label 6) is related to label 4 (correction label 4). FIG. 8D shows the relationship between the initial label and the final minimum label value (corrected label).

  FIG. 8E shows the result of performing the correction process so that the label value becomes the minimum label value while referring to the label of each pixel shown in FIG. 8C using the correspondence relationship between the initial label and the correction label shown in FIG. 8D. Show.

  In addition, when performing correction processing so as to be the minimum label value, the minimum value (the upper left position of the character rectangular area) and the maximum value (the lower right position of the character rectangular area) of the coordinates of the character rectangular area surrounding the pixels of the same label value By calculating (position), the rectangular size of the character rectangular area including the same label value is obtained. A thick line in FIG. 8E indicates a character rectangular area. FIG. 8E illustrates four character rectangular areas with label values of 1, 2, 4, and 7. The minimum value (upper left position of the character rectangular area) and the maximum value (lower right position of the character rectangular area) of each character rectangular area are the respective labels (1, 2, 4, 7 in the example of FIG. 8E). Rectangle size.

  Next, items that cannot be determined as character rectangles for each label are excluded. Specifically, a rectangular area having 16 pixels in the horizontal direction and having 2 pixels in the vertical direction as shown in a label 4 in FIG. 8E, which is long in the horizontal direction or the vertical direction, is horizontal compared to the length in the vertical direction. Because the length of the direction is long, there is a possibility of a horizontal line segment. Therefore, it is determined that the rectangular area of the label 4 is not a character rectangle and is excluded. In this case, in order to determine whether or not the rectangular region is a line segment, for example, a difference between the number of pixels in the horizontal direction and the number of pixels in the vertical direction is calculated, and the calculated difference is equal to or greater than a predetermined threshold (for example, , 12 pixels or more), it can be determined as a line segment.

  Of the obtained rectangular areas, a rectangular area whose size is too small, such as a label 7 in FIG. 8E, which has only 2 pixels in each of the horizontal direction and the vertical direction in total, is not a character and is not a character. Noise pixels (hereinafter also referred to as noise rectangles). Therefore, it is determined that the rectangular area of the label 7 is not a character rectangle and is excluded. In this case, in order to determine whether the size of the rectangular area is small, for example, the number of pixels in the horizontal direction and the number of pixels in the vertical direction are added, and the added value is equal to or less than a predetermined threshold (for example, 6 pixels or less). In some cases, it can be determined as a noise pixel.

  Although not illustrated in FIG. 8E, a label whose rectangular area is too large, for example, a rectangular area whose size is about 1/4 of the size of the input image, can be an image instead of a character. It can be eliminated because of its nature. In this case, when determining that the size of the rectangular area is large, the ratio of the number of pixels of the rectangular area to the number of pixels of the input image is obtained, and the ratio is equal to or larger than a predetermined threshold (for example, 0.25 or larger). In this case, it can be determined that the rectangular area is a label that is too large, that is, not a character rectangle. By performing the non-character rectangle removal process as described above, only labels 1 and 2 in FIG. 8E are finally extracted as character rectangles.

  FIG. 9 is a flowchart illustrating an example of a processing procedure of the character string extraction unit 173. The character string extraction unit 173 generates character string candidates (also referred to as character strings) composed of a plurality of characters based on the character identification information (character rectangle information) generated by the character rectangle extraction unit 172 (specific information generation unit 172a). Character string specifying information to be specified (also referred to as character string information) is generated. The character string specifying information (character string information) is position information for specifying a character string candidate (character string). For example, the upper left and lower right coordinate information of the character string candidate, the horizontal dimension of the character string candidate (Width) and vertical dimension (height). The character string specifying information includes the direction of the character string (horizontal direction, vertical direction).

  More specifically, as shown in FIG. 9, the character string extraction unit 173 calculates the distance between adjacent character rectangles with respect to the character rectangle information output by the character rectangle extraction unit 172 (step S31). Close character rectangles are integrated as a group of the same character string, and character string information is generated.

  The character string extraction unit 173 estimates the direction of the character string from the length of the character string with respect to the character string information in which the character rectangles are integrated (step S32). Further, the character string extraction unit 173 further applies a character rectangle that is determined to be in a different direction, or a character rectangle that belongs to a character string that is determined to be in a different direction, or a character rectangle that is determined to be in a different direction. If the character rectangle can be corrected in the correct character string direction, the character string direction is corrected (step S33).

  The character string extraction unit 173 extracts a character string area from the corrected character string information (step S34), and the character string determined not to belong to the extracted character string area is the character string of the non-character string area. If it exists, it is removed (step S35), and the process is terminated with the remaining information as the final character string information.

  FIG. 10 (FIGS. 10A to 10D) is a schematic diagram showing an example of character string extraction processing by the character string extraction unit 173. FIG. FIG. 10A shows an example of a character rectangle extraction result extracted by the character rectangle extraction unit 172. In the example of FIG. 10A, 21 character rectangles (character candidates) are extracted.

  The distance between adjacent character rectangles is calculated for the character rectangle extraction result shown in FIG. 10A. First, a character string size having the same size as the target character rectangle is set as character string information for an arbitrary target character rectangle. As the method for obtaining the distance of the neighboring character rectangle, the upper left corner is close to the upper right vertex coordinate of the target character rectangle (for example, within ± 5 pixels in the vertical direction and within 10 pixels in the horizontal direction). Search from the coordinate information of all character rectangles to determine whether there is a character rectangle with vertex coordinates, or whether there is a character rectangle with lower-left vertex coordinates close to the lower-right vertex coordinates of the target character rectangle Then, a character rectangle at a close position is extracted as a nearby character rectangle.

  In addition, there is a character rectangle having an upper left vertex coordinate that is close to the lower left vertex coordinate of the target character rectangle in the vertical direction (for example, within ± 5 pixels in the horizontal direction and within 10 pixels in the vertical direction). Or whether there is a character rectangle with the upper right vertex coordinate close to the lower right vertex coordinate of the character rectangle of interest from the coordinate information of all the character rectangles. Extract as a nearby character rectangle.

  When adjacent character rectangles exist in both the horizontal direction and the vertical direction, the closest character rectangle is selected as the adjacent character rectangle. Then, the extracted neighborhood character rectangle is integrated as a character rectangle of the same group as the target character rectangle (labeled as the same character string), and the adjacent character rectangle is connected to the character string size of the target character rectangle The character string information is updated with the new size as the new character string size.

  If there is no neighboring character rectangle, the character string size of the character string information is left as the character rectangle size, and the process proceeds to the next character rectangle of interest. For the next attention character rectangle, a character rectangle that does not yet belong to any character string group is selected. Finally, no character string extraction processing has been performed, and any character string group is not selected. The character string extraction process is repeated until there is no character rectangle that does not belong.

  FIG. 10B illustrates the result of performing the above-described processing on the character rectangle illustrated in FIG. 10A. In FIG. 10B, a character string extracted from a portion surrounded by a thick frame is shown. In the example of FIG. 10B, six groups of character strings with reference numerals 1 to 6 are extracted.

  When the character string extraction process is completed, the horizontal and vertical sizes of the character strings of each group are calculated, and the longer direction is set as the direction of the character string. For example, in the case of a character string having 100 pixels in the horizontal direction and 10 pixels in the vertical direction, the character string is set as the horizontal character string.

  Further, when the size of the character string in the horizontal direction and the size in the vertical direction are approximately the same (for example, when the horizontal direction is 15 pixels and the vertical direction is 10 pixels), the direction of the character string is determined. Therefore, the character string direction is set as indefinite. In the example of FIG. 10B, the direction of the character strings 1, 2, and 3 is the horizontal direction (also referred to as a horizontal direction character string), and the character strings 4, 5, and 6 (including the character rectangle) are directionally indefinite characters. It becomes a column.

  After the character string direction is set for the character strings of all groups, the character string direction is indefinite, and is corrected in the correct character string direction based on the character string information related to the nearby character string. In the example of FIG. 10B, the directionally indefinite character string of reference numeral 4 is in substantially the same horizontal position (for example, the horizontal position is within ± 5 pixels) as the character string of the group with reference numeral 3 located near the upper side, and Since the distance in the vertical direction is also relatively short (for example, 8 pixels or less), it is determined that the character string is in the same direction as the character string of the group of 3. Thereby, the direction indefinite character string of the code | symbol 4 is correct | amended as a character string of a horizontal direction.

  In addition, the direction-indefinite character strings of reference numerals 5 and 6 are left as direction-indefinite character strings because no character string exists in the vicinity.

  FIG. 10C shows an example of the result of correcting the character string direction for the character string illustrated in FIG. 10B. In FIG. 10C, the character string (reference numerals 1, 2, 3, 4) surrounded by a thick frame has a fixed character string direction.

  Next, a character string located in the vicinity (also referred to as a neighborhood character string) and close in size, or the start position of the character string (the left end position of the character string) or the end position (the right end position of the character string) is close ( For example, within 8 pixels), grouping is performed. Thereby, a character string area is extracted. In the case of FIG. 10C, since the character strings 1 to 4 are horizontal character strings and the start position or end position of the character string is close, the character strings 1 to 4 are character strings in the same group. Extract as a region. The character string area is a collection of one or more character strings having the same direction. Then, the direction indefinite character strings of reference numerals 5 and 6 that do not belong to the character string area are removed from the character string information as non-character string areas. The result of extracting the character string region and removing the non-character string region is illustrated in FIG. 10D. That is, the character string area illustrated in FIG. 10D includes a character string (rectangular area indicated by reference numerals 1 to 4) in which the direction of the character string is determined. If there is no character string area, it is determined that there is no character string and the character string information is cleared.

  FIG. 11 is a functional block diagram showing a main configuration of the resolution determination unit 174 in the first embodiment. The resolution determination unit 174 includes an acquisition unit 174a, a search unit 174b, and a selection unit 174c.

The acquisition unit 174a acquires output settings related to the output of the image data or document information related to the document.
The output setting is a setting in the output of the image data. For example, priority is given to or output of the setting of either binary output or multi-value output, and the size of data to be output (file size). This includes any setting that prioritizes image quality, or a compression rate setting for output. The document information is information relating to such a document, and includes, for example, information related to a language used for the document (hereinafter referred to as a language used).

  The acquisition unit 174a receives from the storage unit 24, for example, output settings or document information received from the user via the display panel 4 and stored in the storage unit 24. Further, the present invention is not limited to this, and a processing result by an ACS (automatic color selection) function may be used.

  For example, when the ACS function is activated by a predetermined operation by the user, the display unit (not shown) prompts the user to select the monochrome mode, so that the user can select either grayscale (multivalue) or binary. By selecting, the acquisition unit 174a may acquire the output setting. Further, when the image forming apparatus 100 is set in advance to output in grayscale or binary, the acquisition unit 174a may be configured to acquire either one with reference to the setting information. good.

  Furthermore, it may be configured such that an OCR process is performed on the image data to determine a language used for the document, and the acquisition unit 174a acquires the document information using the determination result.

  In addition, the search unit 174b searches the output resolution table stored in the storage unit 24 for the output resolution corresponding to the character specifying information related to the character candidates of the image data. In the output resolution table, the character specifying information and the output resolution are stored in association with each other according to the output setting acquired by the acquisition unit 174a or the document information.

  The search unit 174b determines one or more character sizes based on the character string specifying information or the character specifying information generated by the specifying information generating unit 172a. For example, the character size (number of pixels) is determined according to the height of the character string candidate in the horizontal direction, the width of the character string candidate in the vertical direction, or the longer value of the character candidate. The search unit 174b searches for the output resolution from the output resolution table based on the determined character size.

  FIG. 12 is a table conceptually illustrating an example of the output resolution table stored in the storage unit 24. In the output resolution table, the rectangular size as the character specifying information is associated with the output resolution or the document information. Here, the rectangle size is the longer value of the width or height of the character candidate (character rectangle).

  FIG. 12A is an output resolution table for a case where the output setting is a binary output or a multi-value output. FIG. 12B is an output resolution table for the case where the output compression rate differs as the output setting. Furthermore, FIG. 12C is an output resolution table when the output setting gives priority to the size of the output data capacity, gives priority to the output image quality, or is intermediate (normal). FIG. 12D is an output resolution table for the case where the language used is Japanese or English as the document information.

  In FIG. 12A, weighting is performed so that the output resolution is lower in the case of multi-value output than in the case of binary output. That is, for the same output resolution, a larger rectangular size is set for binary output than for multi-value output.

  In FIG. 12B, the lower the compression rate, the lower the output resolution. That is, for the same output resolution, a larger rectangular size is set as the compression rate is higher.

  In FIG. 12C, when priority is given to the size of the output data capacity, that is, when priority is given to reducing the output file size (when priority is given to file size), the output is given more than when priority is given to the output image quality. Weighted so that the resolution is lower. That is, for the same output resolution, a larger rectangular size is set when image quality is prioritized than when file size is prioritized.

  In FIG. 12D, weighting is performed so that the language with higher visibility has a lower output resolution. In the above-mentioned examples of Japanese and English, the visibility of Japanese including Chinese characters is lower than that of English. Therefore, for the same output resolution, a larger rectangular size is set when the language used is Japanese than when the language used is English.

  The search unit 174b searches the output resolution corresponding to the character specifying information related to the character candidate of the image data based on the output setting or document information acquired by the acquisition unit 174a and the output resolution table.

  When there is only one output resolution searched from the output resolution table by the search unit 174b, the output resolution is handled as the optimum output resolution.

  However, when a plurality of output resolutions are searched by the search unit 174b, the selection unit 174c selects one of the searched output resolutions based on the number of character candidates corresponding to each of the searched output resolutions, and outputs the optimum output. Select as the resolution. Details of the selection method will be described later.

  FIG. 13 is a flowchart illustrating an example of a processing procedure of the resolution determination unit 174. Hereinafter, processing when the resolution determination unit 174 determines the optimum output resolution for the read image data will be described. The acquisition unit 174a of the resolution determination unit 174 acquires the output setting or document information as described above, and the character specification generated by the character rectangle extraction unit 172 (specific information generation unit 172a) according to the output setting or the document information. Based on the information (character rectangle information), the search unit 174b searches the output resolution table for the output resolution, and the selection unit 174c determines the optimum output resolution.

  First, the acquisition unit 174a acquires output settings or document information (step S41). The output setting or document information acquisition processing by the acquisition unit 174a has already been described, and a detailed description thereof will be omitted.

  Next, the resolution determination unit 174 determines Condition 1 (Step S42). Condition 1 is a condition that a character string exists or a condition that character string information exists.

  When it is determined that the condition 1 is satisfied (step S42: YES), the search unit 174b determines the rectangular size of the character string of each group using the character string information, and searches for the output resolution corresponding to the determined rectangular size. (Step S43). The search is performed based on the output resolution table.

Hereinafter, the process in step S43 will be described in detail.
FIG. 14 (FIGS. 14A and 14B) is an exemplary diagram showing an example of the character string specifying information and the character specifying information. FIG. 14A is an example of character string specifying information extracted by the character string extracting unit 173, and FIG. 14B is an example of character specifying information extracted by the character rectangle extracting unit 172.

  For convenience of explanation, in the following, the character string specifying information and the character specifying information of the image data are the same as those in FIG. 14, and an example in which the output setting of multi-value output is acquired by the acquisition unit 174a will be described as an example. explain.

  When the character string information illustrated in FIG. 14A exists, the above condition 1 is satisfied (step S42: YES). When the condition 1 is satisfied, the search unit 174b determines which output resolution table character size corresponds to the rectangular size determined based on the height of the character string in the horizontal direction or the width of the character string in the vertical direction. The output resolution corresponding to the rectangular size is searched from the output resolution table.

  For example, in FIG. 14A, in the case of the character string of the character string label 1, the height of the character string (ey-sy), that is, the height of the character candidate (character rectangle) included in the character string is 50. The rectangular size of the character string of the column label 1 is 50.

  In this embodiment, since the output is multi-valued (output setting), the search unit 174b outputs “multi-value” and the rectangular size “50” from the output resolution table of FIG. 12A. The output resolution corresponding to "" is searched. As a result, an output resolution of “150 × 150 dpi” is searched.

  At this time, the selection unit 174c counts the number of character candidates (character rectangles) excluding the noise rectangle included in the character string of the character string label 1 and associates it with 150 × 150 dpi, for example, in the storage unit 24. Memorize temporarily.

  The same processing is performed on the other character string labels 2 to 9. In the character string labels 2 to 9, since the height (rectangular size) of the character string is 30, an output resolution of “200 × 200 dpi” is retrieved from the output resolution table of FIG. 12A.

  The selection unit 174c counts the number of character candidates (character rectangles) excluding the noise rectangle included in the character strings of the character string labels 2 to 9 and associates them with 200 × 200 dpi, for example, the storage unit 24 Memorize temporarily.

  Next, the selection unit 174c selects one of the retrieved output resolutions from the retrieved output resolution and determines it as the optimum output resolution (step S44). Hereinafter, the determination of the optimum output resolution by the selection unit 174c will be described in detail.

  FIG. 15 is a graph showing the relationship between the detected output resolution and the number of counted character candidates (character rectangles). Hereinafter, the number of counted character candidates (character rectangles) is referred to as a count value. For convenience of explanation, the case of FIG. 15 will be described as an example.

  FIG. 15 shows the count values when the output resolution is 150 × 150 dpi, 200 × 200 dpi, and 300 × 300 dpi. The count value when the output resolution is 150 × 150 dpi is 150, the count value when the output resolution is 200 × 200 dpi is 550, and the count value when the output resolution is 300 × 300 dpi is Assume that the sum of all count values is 1000.

  When determining the optimum output resolution, the selection unit 174c sequentially adds, for example, the number of character candidates corresponding to each output resolution from the highest detected output resolution, and the count value and all of the character candidates are added. When the ratio to the number is equal to or greater than a predetermined threshold, the searched output resolution relating to the character candidate added last is selected as the optimum output resolution.

  For example, when the threshold is 0.5, the ratio is 0.3 for the highest output resolution of 300 × 300 dpi. On the other hand, when the number of character candidates corresponding to the highest output resolution is added to the number of character candidates corresponding to the next highest output resolution (200 × 200 dpi), the ratio relating to the count value is 0.85 and the threshold value It exceeds 0.5. Accordingly, at this time, the output resolution “200 × 200 dpi” related to the count value (character candidate) added last is selected as the optimum output resolution by the selection unit 174c.

  In the present invention, the method for determining the optimum output resolution is not limited to this, and the output resolution associated with the highest count value may be selected as the optimum output resolution.

  As described above, when the optimal output resolution is determined, the resolution determination unit 174 outputs the result of determination of the optimal output resolution (step S45), and ends the process.

  On the other hand, when the condition 1 is not satisfied (step S42: NO), the resolution determination unit 174 determines the condition 2 (step S46). Condition 2 is a condition that a character candidate (character rectangle) exists or a condition that character rectangle information (character specifying information) exists.

  When it is determined that the condition 2 is satisfied (step S46: YES), the search unit 174b determines the rectangle size of the character candidate (character rectangle) using the character specifying information (character rectangle information), and sets the determined rectangle size. The corresponding output resolution is searched (step S47). The search is performed based on the output resolution table.

Hereinafter, the process in step S47 will be described in detail.
For example, when the character specifying information illustrated in FIG. 14B exists, it is determined that the above condition 2 is satisfied (step S46: YES). The character rectangle information in FIG. 14B includes the label number of the character rectangle (character candidate), the upper left coordinate information (sx, sy) of the character rectangle, the lower right coordinate information (ex, ey) of the character rectangle, and the character rectangle. It consists of a label number of a character string (a character rectangle that does not belong to any character string in the case of 0). When there is no character string and only a character rectangle, the character string numbers are all 0.

  The search unit 174b obtains the height (ey-sy) and width (ex-sx) of the character rectangle, selects the longer one of the height and width as the character rectangle size, and selects the noise rectangle and the small size. If it is not a rectangle (for example, 5 or less), it is determined which character size of the output resolution table the character rectangle size corresponds to, and the output resolution is searched from the output resolution table for each rectangle size. The search of the output resolution by the search unit 174b has already been described in step S43, and a detailed description thereof will be omitted.

  Next, the selection unit 174c selects one of the retrieved output resolutions from the retrieved output resolution and determines it as the optimum output resolution (step S48). Hereinafter, the determination of the optimum output resolution by the selection unit 174c has already been described in step S44, and detailed description thereof will be omitted.

  As described above, when the optimal output resolution is determined, the resolution determination unit 174 outputs the result of determination of the optimal output resolution (step S49), and the process is terminated.

  If the character specifying information does not exist, it is determined that the above condition 2 is not satisfied (step S46: NO), and the resolution determining unit 174 outputs a preset output resolution (step S50). That is, the output resolution for when the resolution determination is impossible is stored in advance in the storage unit 24. At this time, the selection unit 174c selects the output resolution for when the resolution determination is impossible as the highest output resolution. The output resolution at this time may always be a fixed value, or a default value may be set in advance according to the purpose.

  Also, the conversion of the output resolution can be performed by the following two methods by storing the read image data. The first method is a method using one-pass scanning, in which output resolution is estimated and output resolution in the main scanning direction and sub-scanning direction is set by interpolation calculation. The second method is a method using two-pass scanning, in which the output resolution is estimated, the reading speed of the scanner is changed, and the original is read again. In this case, the output resolution in the sub-scanning direction is optically changed, and the output resolution in the main scanning direction is set by interpolation calculation.

  In the present embodiment, English has been described as an example of a language with high visibility and Japanese as an example of a document with low visibility, but the present invention is not limited to this. In addition, Korean, Chinese, etc. can be added as a use document with low visibility, and French, German, etc. can be added as use languages with high visibility. Therefore, the language used may be handled in the same manner as in the case where the language used is Japanese or English as described above.

(Embodiment 2)
The present invention is not limited to the above description. For example, assuming that Japanese and English are mixed in such a manuscript, the image forming apparatus 100 may be configured to cope with such a case.

  For example, in a manuscript in which English and Japanese are mixed (hereinafter referred to as a Japanese-English mixed manuscript), when the Japanese-English mixed manuscript is set to Japanese, the output image is judged because it is judged from high resolution. There is little impact on visibility. However, if the Japanese-English mixed manuscript is set to English, since the determination is made based on the low resolution, there is a possibility that in the output image, the visibility of kanji or the like is lowered and the reading becomes impossible. Therefore, when English is selected in the language setting of the input document, when such a document is a mixed document of Japanese and English, a display that prompts the user to select the setting for Japanese is performed. There may be.

  Further, the present invention is not limited to the above description. For example, the image forming apparatus 100 may be configured to handle the mixed document of Japanese and English using the result of OCR processing.

  Specifically, the English dictionary data is matched with the character feature amount extracted from the input manuscript in units of characters, and the value indicating the highest degree of matching is set for each character as the character reliability. Next, the number of characters whose reliability for each character is greater than a predetermined value is counted, and if the count number is higher than the predetermined rate, If the above processing is performed and the ratio is lower than the predetermined ratio, the subsequent processing may be performed as a Japanese manuscript.

(Embodiment 3)
In the above description, the present invention has been described by taking as an example the case where any output setting is acquired or the case where document information is received, but the present invention is not limited thereto. In the above, three settings are listed as output settings, and one example is disclosed as document information. However, it can be assumed that the setting relating to the document is a combination of these four settings. As such an example, a combination of output setting and document information can be assumed. Therefore, the image forming apparatus 100 according to the third embodiment is configured to be able to cope with such a combination of settings.

  FIG. 16 is a table conceptually illustrating another example of the output resolution table stored in the storage unit 24. In the output resolution table of FIG. 16, the combination of the output setting and the document information is associated with the output resolution. FIG. 16A shows a combination of document information and output settings when the language used is Japanese, and FIG. 16B shows a combination of document information and output settings when the language used is English. .

  For example, the search unit 174b and the selection unit 174c appropriately search for the output resolution corresponding to the character specifying information related to the character candidate of the image data based on the output resolution table in any one of FIGS. Determine the output resolution.

(Embodiment 4)
FIG. 17 is a block diagram illustrating an example of the configuration of the image reading apparatus 120 according to the fourth embodiment. The image reading device 120 outputs multivalued image data. The image forming apparatus 100 includes a color image input device 1, a color image processing device 50, a transmission device 3, and the like.

  The color image processing apparatus 50 includes an A / D conversion unit 11, a shading correction unit 12, a document type determination unit 13, an input tone correction unit 14, a region separation processing unit 15, a color correction unit 16, a spatial filter processing unit 19, and a resolution. A conversion processing unit 20, an output tone correction unit 21, a compression processing unit 23, a storage unit 24, a processing parameter determination unit 17, and the like are provided.

  The color image input device 1 is composed of, for example, a color scanner having a CCD (Charge Coupled Device). The color image input apparatus 1 reads a reflected light image from an original as an 8-bit or 10-bit RGB (R: red, G: green, B: blue) analog signal using a CCD and outputs the read image to the color image processing apparatus 50. To do.

  An analog signal read by the color image input device 1 is converted into an A / D conversion unit 11, a shading correction unit 12, a document type determination unit 13, an input tone correction unit 14, an area separation process in the color image processing device 50. 15, color correction unit 16, processing parameter determination unit 17, spatial filter processing unit 19, resolution conversion processing unit 20, output tone correction unit 21, and compression processing unit 23. In addition, since the process of each part is the same as that of the case of Embodiment 1, description is abbreviate | omitted. A digital camera can also be used as the image reading apparatus.

  Next, FIG. 18 shows processing when multi-valued input image data is output in binary. FIG. 18 is a block diagram illustrating an example of the configuration of the image reading apparatus 120 according to the fourth embodiment. In addition, since the process of each part is the same as that of the case of Embodiment 1, description is abbreviate | omitted.

  FIG. 19 is a schematic diagram showing an example of the resolution setting method in the first to fourth embodiments. In the image forming apparatus 100 and the image reading apparatus 120 according to the first to fourth embodiments, in the manual setting mode in the scan function, for example, as shown in FIG. 19A, the user appropriately sets the resolution via the display unit. There is a need to. In addition, there are various setting items such as color settings, document mode settings, file format settings, and compression rate settings.

  For example, in the automatic setting mode, the image forming apparatus 100 according to the present embodiment prepares an operation screen as shown in FIG. 19B, and simply presses the scan start button to perform other settings including the resolution setting shown in FIG. 19A ( For example, processing settings such as top and bottom direction and blank page skipping are automatically performed, and optimal scan data can be acquired. For the automatic setting, for example, a function called ACS (Auto Color Select) has already been generally used for color, and color setting can be automatically performed by using the function.

  FIG. 20 is a schematic diagram illustrating an input screen that receives an input of the output setting or the document information from the user in the image forming apparatus 100 according to the first embodiment and the image reading apparatus 120 according to the fourth embodiment. For example, as shown in FIG. 19B, when there is a “setting input” button, the user presses the “setting input” button to display a setting input screen as shown in FIG. The user can input the output setting (mode, compression rate, output format in FIG. 20) or the document information (document language in FIG. 20) by appropriately operating the setting input screen. When color or gray scale is selected as the output format, the image data is output in multiple values, and when black and white binary is selected, the image data is output in binary.

  Each of the embodiments described above can also be applied to image data (images) downloaded via a network. Even if the resolution of the downloaded image data is unknown, the character size can be determined to determine the output resolution. Further, when downloading image data from a server such as a cloud, it is possible to determine the resolution on the server side and download the compressed image data. In this case, the server corresponds to the image processing apparatus of the present embodiment. In this case, the amount of image data to be downloaded can be reduced.

  In each of the above-described embodiments, the optimum output resolution determination process described above is recorded in a computer-readable recording medium M in which program code (execution format program, intermediate code program, source program) of a program to be executed by a computer is recorded. It is also possible to record image processing performed. As a result, the recording medium M on which the program code for determining the optimum output resolution described above is recorded can be provided in a portable manner.

  In the present embodiment, the recording medium M may be a memory, for example, a program medium such as a ROM since processing is performed by a microcomputer. It may be a program medium provided with a reading device and readable by inserting a recording medium into the reading device.

  In any case, the stored program may be configured to be accessed and executed by the microprocessor, or in any case, the program code is read and the read program code is displayed on the microcomputer. The program code may be downloaded to a program storage area that has not been executed and the program code executed. It is assumed that this download program is stored in the main device in advance.

  Here, the program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a flexible disk or a hard disk, a CD-ROM / MO / MD / DVD, or the like. Optical disk system, IC card (including memory card) / optical card system, mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory: registered trademark), flash ROM, etc. It may be a medium that carries a fixed program including the semiconductor memory according to the above.

  In the present embodiment, since the system configuration is such that a communication network including the Internet can be connected, the medium may be a medium that dynamically carries a program so as to download a program code from the communication network. When the program code is downloaded from the communication network as described above, the download program may be stored in the main device in advance, or may be installed from another recording medium. This embodiment can also be realized in the form of a computer data signal embedded in a carrier wave, in which the above-described program code is embodied by electronic transmission. Further, the above-described image processing method is executed by reading the above-mentioned recording medium by a digital color image forming apparatus or a program reading apparatus provided in a computer system.

  The computer system includes an image input device such as a flatbed scanner, a film scanner, and a digital camera, a computer that performs various processes such as the image processing method by loading a predetermined program, and a CRT display that displays the processing results of the computer. An image display device such as a liquid crystal display and a printer that outputs the processing results of the computer to paper or the like. Furthermore, a network card or a modem is provided as communication means for connecting to a server or the like via a network.

  The technical features described in the above embodiments of the present invention can be combined with each other to form a new technical plan.

  The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In Embodiment 1 of the present invention, in an image processing apparatus that determines an output resolution related to output processing of document image data, a specific information generating unit that generates character specifying information for specifying character candidates included in the image data; A storage that stores an output setting relating to output, or an acquisition unit that obtains original information relating to the original, and a table that associates the character specifying information and the output resolution in accordance with the output setting or the original information. And a search unit that searches the table for output resolution corresponding to the character identification information generated by the specific information generation unit in accordance with the output setting or document information acquired by the acquisition unit. And

  According to the present invention, the specification information generation unit generates character specification information for specifying a character candidate included in the image data, the acquisition unit acquires the output setting or the document information, and the table of the storage unit The search unit searches for an output resolution corresponding to the character specifying information generated by the specifying information generating unit in accordance with the output setting or document information acquired by the acquiring unit.

  In Embodiment 2 of the present invention, when a plurality of output resolutions are searched, one of the searched output resolutions is determined based on the number of character candidates related to the character specifying information corresponding to each of the searched output resolutions. A selection unit for selecting is provided.

  According to the present invention, when a plurality of output resolutions are searched, the selection unit selects one of the searched output resolutions based on the number of character candidates related to the character specifying information corresponding to each of the searched output resolutions. As the optimal output resolution.

  In the embodiment 3 of the present invention, the output setting includes either a binary output or a multi-value output, and the table is a binary output in the case of a multi-value output. In this case, the output resolution is set to be lower.

  According to the present invention, the output setting is, for example, a setting of either binary output or multi-value output, and the table is a binary output in the case of multi-value output. In some cases, the output resolution is set to be low, and the data capacity is suppressed while ensuring the visibility of characters.

  In Embodiment 4 of the present invention, the output setting includes a setting for giving priority to the size of the output data capacity or giving priority to the image quality for output, and the table gives priority to the size of the output data capacity. In this case, the output resolution is set to be lower than when priority is given to the output image quality.

  According to the present invention, the output setting is, for example, a setting that gives priority to the size of the output data capacity or priority to the image quality to output, and the table gives priority to the size of the output data capacity. In this case, the output resolution is set to be lower than when priority is given to the output image quality, and the size of the data capacity can be suppressed in accordance with a user instruction.

  In Embodiment 5 of the present invention, the output setting includes a setting of a compression rate related to output, and the table is set such that the output resolution is lower as the compression rate is lower. And

  According to the present invention, the output setting is, for example, a compression ratio setting related to output, and the table is set such that the lower the compression ratio, the lower the output resolution, and the character visibility. Ensure balance between securing and compression rate.

  In Embodiment 6 of the present invention, the document information includes information related to a language used, and the table is set such that the output resolution is lower for a language with higher visibility. .

  According to the present invention, the document information is, for example, information related to a language used, and the table is set so that the output resolution becomes lower as the language used becomes more visible to ensure the visibility of characters. ing.

  In Embodiment 7 of the present invention, the selection unit sequentially adds the number of character candidates corresponding to each searched output resolution from the highest output resolution searched, and adds the added value and all of the character candidates. When the ratio to the number is equal to or greater than a predetermined threshold, the searched output resolution related to the character candidate added last is selected.

  According to the present invention, the selection unit sequentially adds the number of character candidates corresponding to each searched output resolution from the highest output resolution searched, and the added value and the total number of the character candidates Is equal to or greater than a predetermined threshold, the searched output resolution relating to the character candidate added last is selected as the optimum output resolution.

  In Embodiment 8 of the present invention, the image data includes a character string including the character candidate, and the search unit searches for the output resolution based on character specifying information related to the character candidate of the character string. Identify that.

  According to the present invention, when searching for an output resolution related to the character string, the search unit searches for the output resolution based on character specifying information related to character candidates of the character string.

  In Embodiment 9 of the present invention, the image processing apparatus according to any one of the above embodiments is provided, and image formation is performed on a sheet-like recording medium based on image data processed by the image processing apparatus. Features.

  According to the present invention, for example, image formation is performed on a sheet-like recording sheet based on image data that has been subjected to output processing using the optimum output resolution determined by the image processing apparatus.

  In Embodiment 10 of the present invention, in a resolution determination method for determining an output resolution related to output processing in an image processing apparatus that performs output processing of document image data, character specification that specifies character candidates included in the image data Information is generated, output settings related to output or document information related to the document is acquired, and acquired based on a table in which the character specifying information and output resolution are associated with each other according to the output setting or the document information. The output resolution corresponding to the generated character specifying information is searched according to the output setting or document information.

  According to the present invention, the character specifying information is generated, the output setting or the manuscript information is acquired, and the generated character specifying information is handled according to the acquired output setting or manuscript information based on the table. The output resolution to be searched is searched.

17 Processing Parameter Determination Unit 24 Storage Unit
DESCRIPTION OF SYMBOLS 50 Color image processing apparatus 100 Image forming apparatus 172 Character rectangle extraction part 172a Specific information generation part 174 Resolution determination part 174a Acquisition part 174c Selection part 174b Search part M Recording medium

Claims (9)

In an image processing apparatus for determining an output resolution related to output processing of document image data,
A specific information generating unit that generates character specifying information that is position information for specifying a character candidate included in the image data;
An acquisition unit that acquires output settings related to output or document information related to the document;
A storage unit storing a table in which the character specifying information and the output resolution are associated with each other according to the output setting or the document information;
A search unit that searches the table for an output resolution corresponding to the character identification information generated by the specific information generation unit according to the output setting or document information acquired by the acquisition unit ;
A selection unit that selects one of the searched output resolutions based on the number of character candidates related to the character identification information corresponding to each of the searched output resolutions when a plurality of output resolutions are searched ; A featured image processing apparatus. The output setting includes a setting of either binary output or multi-value output,
2. The image processing apparatus according to claim 1, wherein the table is set so that the output resolution is lower in the case of multi-value output than in the case of binary output. The output setting includes a setting for giving priority to the size of the output data capacity or giving priority to the image quality to be output.
The image processing according to claim 1, wherein the table is set so that the output resolution is lower when priority is given to the size of the output data capacity than when priority is given to output image quality. apparatus. The output setting includes a setting of a compression ratio related to output,
The image processing apparatus according to claim 1, wherein the table is set such that the output resolution decreases as the compression rate decreases. The manuscript information includes information related to the language used,
The image processing apparatus according to claim 1, wherein the table is set such that the output resolution is lower for a language with higher visibility. The selection unit sequentially adds the number of character candidates corresponding to each searched output resolution from the highest output resolution searched, and the ratio between the added value and the total number of character candidates is equal to or greater than a predetermined threshold value. The image processing apparatus according to claim 1 , wherein the output resolution searched for the character candidate added last is selected. The image data has a character string including the character candidates,
The search unit is an image processing apparatus according to any one of claims 1 to 6, wherein the searching the output resolution based on the character specific information relating to the character candidate of the character string. An image processing apparatus according to any one of claims 1 to 7 ,
An image forming apparatus that forms an image on a sheet-like recording medium based on image data processed by the image processing apparatus. In a resolution determination method for determining an output resolution related to output processing in an image processing apparatus that performs output processing of document image data,
Generating character specifying information which is position information for specifying a character candidate included in the image data;
Obtain output settings related to output or document information related to the document,
Based on the table in which the character specifying information and the output resolution are associated with each other according to the output setting or the document information, the output resolution corresponding to the generated character specifying information is searched according to the acquired output setting or the document information. And
When a plurality of output resolutions are searched , the resolution determination is characterized by selecting one of the searched output resolutions based on the number of character candidates related to the character specifying information corresponding to each of the searched output resolutions Method.

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