JP2004362541A - Image processing device, program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a data volume, and to enable high speed processing, in displaying a text image overlapped on a background image. <P>SOLUTION: The text image of a text portion extracted from an image, and the background image of the remained image in which the extracted portion is not made up for are processed through a predetermined resolution change process and a predetermined compressed encoding process, and stored in one or more files. When displaying the image, the text image of opaque color is superposed and overwritten in the position of the text portion of the background image (Step S13). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image processing device, a program, and a storage medium.

  Patent Literature 1 discloses a technique for removing a character portion of an image and creating a background image filled with surrounding colors.

  Patent Literature 2 discloses a coding technique that includes first means for extracting and coding character information from a color image and second means for coding by lowering the resolution of image data, and combining the respective data. Proposed.

  Patent Document 3 proposes a technique in which text data extracted from image data can be registered in search information, and the image data is stored at a low resolution.

  Patent Document 4 proposes a technique in which a color document image in which a natural image and a character are mixed is divided into a character background block and an image data block, and encoding suitable for each area is performed, and the resolution of the picture area is set low. ing.

Japanese Patent No. 2611012 JP-A-8-186711 JP 2001-297104 A Japanese Patent No. 3108133

  For image data of an image including a character image, the character image is separated, and image processing and compression processing suitable for each of the separated character image and background image are performed. Then, the character images are superimposed from above. It is possible to improve the visibility of a character image and the visibility of a background image by saving the file in a file format having a multi-layer function.

  On the other hand, in the technique disclosed in Patent Document 1, a technique of removing a character portion of an image and creating a background image filled with peripheral colors is disclosed.

  However, in the technique disclosed in Patent Document 1, since a process of removing a character portion of an image and filling the image with surrounding colors is performed, there is a problem that a data amount cannot be reduced and high-speed processing cannot be performed.

  An object of the present invention is to reduce the amount of data and to perform high-speed processing when displaying a character image over a background image.

  According to the first aspect of the present invention, there is provided an extracting means for extracting a character portion of an image from image data, and filling a predetermined image in a region where the character image as the extracted image and the character portion of the extracted image are extracted. And a file creating unit that saves the background image without being saved as one or more files separately.

  According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, when the image data is a color image, the extraction unit performs the extraction at a predetermined sampling interval.

  According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect, when the image data is a color image, the character image is converted into one or more binary images. In the file.

  According to a fourth aspect of the present invention, in the image processing apparatus according to the third aspect, the extracting means extracts a character portion after binarizing the image data, and extracts a color image corresponding to the character portion. Is extracted to specify the character color.

  According to a fifth aspect of the present invention, in the image processing apparatus according to any one of the first to fourth aspects, when the image data is a color image, the color of the character image is reduced. The character image is stored in the file as an image.

  According to a sixth aspect of the present invention, in the image processing apparatus according to any one of the first to fifth aspects, the file creating unit performs lossless compression on the extracted character image, and the extracted background image is Each of the files is compressed and encoded by irreversible compression, and is stored as the one or more files.

  According to a seventh aspect of the present invention, in the image processing apparatus according to the sixth aspect, the file creating means smoothes the extracted background image before the lossy compression.

  According to an eighth aspect of the present invention, in the image processing apparatus according to the sixth or seventh aspect, the file creating means performs an OCR process on the extracted character image, and outputs the OCR result as a transparent text. The file is stored as a layer-managed file having the data, the extracted character image, and the extracted background image as layers, and the text data layer is higher than the character image layer. Layer.

  According to a ninth aspect of the present invention, a character image which is an image obtained by extracting a character portion of an image from image data and a background image which is not filled with a predetermined image in a region where the character portion of the extracted image is extracted are included. Image processing means for creating an image in which the character image is superimposed in an opaque color on an area where the character portion of the background image is extracted, for one or a plurality of separately stored files; Device.

  According to a tenth aspect of the present invention, there is provided an extraction process for extracting a character portion of an image from image data, and filling a predetermined image in a region where the extracted character image and a character portion of the extracted image are extracted. A computer-readable program that causes a computer to execute a file creation process of separately saving one or more files with a background image that has not been saved.

  According to an eleventh aspect of the present invention, a character image, which is an image obtained by extracting a character portion of an image from image data, and a background image which is not filled with a predetermined image in a region where the character portion of the extracted image is extracted, are included. A computer that causes a computer to execute an image creation process of creating an image in which the character image is overlapped with an opaque color on an area where the character portion of the background image is extracted, for one or a plurality of separately stored files. It is a readable program.

  According to a twelfth aspect of the present invention, there is provided a storage medium storing the program according to the tenth or eleventh aspect.

  According to the first and tenth aspects of the present invention, since the background image is not filled in the area after the character image is extracted, the image obtained by overlapping the character image with the opaque color on the area where the character portion of the background image is extracted is used. If the file is created, the above-mentioned file including the character image and the background image can reduce the data amount, and can quickly create an image that does not impair the readability of the character. Further, since the character image and the background image are separately stored in one or a plurality of files, even if the entire image including the character image is smoothed, the background image is provided to the user. Has no influence on the smoothing process.

  According to a second aspect of the present invention, in the first aspect of the present invention, the storage capacity required for processing is reduced, and high-speed processing is enabled.

  According to the invention described in claim 3, in the invention described in claim 1 or 2, the color of the character portion is generally written in one color or not so many colors. The color of a part can be specified by clustering processing or the like, and a character image can be created from one or a plurality of binary images of a color corresponding to the clustering result.

  According to a fourth aspect of the present invention, in the third aspect, a character image can be created from one or a plurality of binary images of a color corresponding to a clustering result.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the number of colors used for the character portion is usually not so large. It is sufficient to hold only an image in which the number of colors has been reduced to a bit or an image in which the number of colors has been reduced.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, a binary image of a character is a compression format suitable for a character image, and a background image is a compression format suitable for a background. , And the file size can be reduced. Further, by compressing the character image by the lossless compression method, even when it is desired to convert the character image into a character code by a process such as OCR in the future, the OCR process can be performed without lowering the recognition rate.

  According to a seventh aspect of the present invention, in the sixth aspect of the invention, it is possible to prevent the image finally provided to the user from being affected by the smoothing process.

  According to the invention described in claim 8, in the invention described in claim 6 or 7, a file having a multi-layer function capable of performing a text search can be created.

  According to the ninth and eleventh aspects of the present invention, the background image is obtained by superimposing an image obtained by superimposing the character image in an opaque color on the region where the character portion of the background image is extracted without performing padding in the region after extracting the character image. Since the file can be created, the above-mentioned file including the character image and the background image can reduce the amount of data, and can quickly create an image that does not impair the readability of the character.

  An embodiment of the present invention will be described.

  FIG. 1 is a block diagram showing an electrical connection of the image processing apparatus 1 according to the present embodiment. As shown in FIG. 1, each of the image processing apparatuses 1 is a computer such as a PC, and performs various operations and centrally controls each unit of the image processing apparatus 1, and a memory including various ROMs and RAMs. 12 are connected by a bus 13.

  The bus 13 includes, via a predetermined interface, a magnetic storage device 14 such as a hard disk, an input device 15 such as a keyboard and a mouse, a display device 16, and a storage medium reading device 18 that reads a storage medium 17 such as an optical disk. And an image reading device 21 for reading an image, and a predetermined communication interface 19 for communicating with the network 4 is connected. In addition, as the storage medium 17, various media such as an optical disk such as a CD and a DVD, a magneto-optical disk, and a flexible disk can be used. As the storage medium reading device 18, an optical disk device, a magneto-optical disk device, a flexible disk device, or the like is used depending on the type of the storage medium 17.

  The image processing apparatus 1 reads an image processing program 20 that implements the program of the present invention from the storage medium 17 that implements the storage medium of the present invention, and installs the image processing program 20 in the magnetic storage device 14. These programs may be downloaded and installed via a network 4 such as the Internet. With this installation, the image processing apparatus 1 is in a state where it can execute predetermined processing described later. Note that the image processing program 20 may operate on a predetermined OS.

  FIG. 2 is a functional block diagram of functions realized by the image processing apparatus 1 based on the image processing program 20, and FIG. 3 is a flowchart of processing executed by the image processing apparatus 1. FIG. 5 is an explanatory diagram of a process executed by the image processing apparatus 1.

  As shown in FIG. 2, FIG. 3, and FIG. 5, first, the image of the document is read by the image reading device 21 as a 600 dpi color image (step S1). Then, the following two processes are performed on the read image data (the original image 41 in FIG. 5A).

  In the first process, the image data read in step S1 is subjected to resolution conversion by the resolution conversion / compression unit 31 to reduce the data amount (for example, to convert to a 300 dpi color image) (step S2). From the color image, each character color is specified by the color reduction unit 33, binarization for each character color is performed by the binarization unit 34 (step S3), and at least the character area (pixel or area) is processed by the character extraction unit 32. ) Is extracted (extraction means, extraction processing) (step S4), and a character image 42, which is a binary image, is created (FIG. 5B) (step S5). The compression encoding is performed by a lossless compression method such as MMR (step S6), and the data amount is further reduced. Here, although the information is specified as characters, information such as ruled lines other than the characters may be extracted together with the characters. In addition, an area that is likely to be a character may be extracted as a character area by paying attention to an edge or the like that is a characteristic of a character or a ruled line. This is because the purpose is not necessarily to accurately extract a character region from an image.

  In the second processing, the resolution conversion / compression unit 31 performs resolution conversion on the image data read in step S1 (including character images) by a lossy compression method such as JPEG, and performs the first processing. The data amount is further reduced (for example, conversion into a 150 dpi color image) (step S7). In this case, the original image 41 to be processed is used after the character image 42 is extracted in step S3 without filling in the area after the character extraction (for example, giving a predetermined pixel value). This is used as a background image 43 (FIG. 5 (b)) (step S8), which is compression-coded by the resolution conversion / compression unit 31 (step S9) to further reduce the data amount.

  The character image 42 and the background image 43 thus created are separately stored as one or a plurality of files (PDF files) (file creation means, file creation processing) (step S10). Specifically, for example, saving as a single file such as PDF or JPEG2000 having a multi-layer function is conceivable. In this case, a background image is arranged on the first layer (lower layer) and a character image is arranged on the second layer (upper layer) of the layer-managed file.

  The process of displaying the data of the file created in this manner on the display device 16 will be described with reference to the functional block diagram of FIG. 2, the flowchart of FIG. 4, and the explanatory diagram of FIG.

  That is, when the image processing apparatus 1 displays the file created in step S10 on the display device 16 (Y in step S11), the resolution conversion / compression unit 31 performs resolution conversion of the character image 42 and outputs the character image. 42 is a character image 44 whose resolution has been converted, and the resolutions of the character image 44 and the background image 43 are made uniform (step S12). Then, the character image 44 of the character corresponding to the character position on the background image 43 is overwritten as an opaque color (image 45 in FIG. 5D) (step S13). If the superimposed image is displayed (or printed, transmitted to the outside, or the like) on the display device 16, an image in which the character image 44 and the background image 43 overlap can be viewed as one image.

  As described above, since the background image 43 does not fill in the area after the extraction of the character image 42, the above-described file including the character image 42 and the background image 43 can reduce the data amount, and An image that does not impair the readability of characters can be created at high speed.

  In step S3, by extracting an image from the original image 41 at a predetermined sampling interval, the storage capacity required for the processing can be reduced, and high-speed processing can be performed. That is, in the technique disclosed in Patent Document 1 described above, a memory for calculating at least the background of a character is required in order to extract the character portion and obtain the color of the background, but in the present embodiment, This becomes unnecessary. That is, in the present embodiment, since the character image 44 is displayed in an opaque color on the background image 43, it is not necessary to specify the background color of the original image 41 and delete the character portion from the original image 41. The extraction processing of the character image 42 is performed at predetermined intervals, and the extraction processing of the background color is not required, and the processing time and the memory required for the processing time are not required.

  As described above, one or more binary images are created as the character image 42. This is because the color of the character portion is generally written in one color or a small number of colors, such as black, red, and blue, and the color of the character portion is specified by clustering processing or the like. Then, a plurality of binary images of a color corresponding to the clustering result are created.

  An example of this clustering method will be described. That is, in steps S3 and S4, the character image is binarized first, and the character portion is extracted from the binary image. Here, a frequency histogram is created in a three-dimensional RGB space with reference to the pixel values (RGB values) of the color original image corresponding to the extracted character part. Next, clustering for dividing the frequency histogram into several classes is performed. This clustering method does not use a special method, but may use a generally known K-mean method or the like.

  When one or more character images 42 are created as the character image 42, a color multi-value image may be used instead of a binary image. Since the number of colors used for the character portion is usually not so large, 160,000 colors or the like are unnecessary as in a general color original. That is, it is sufficient to hold only one image reduced in color to 4 bits or 8 bits, or an image reduced in color to a plurality of images, which has the effect of increasing the contrast and visibility for the user.

  In the above-described example, character recognition (OCR) processing is performed on the extracted character image 42 (step S5), and the character recognition result is used as transparent text data, and the uppermost layer of the layer-managed file is processed. (Third layer), a background image may be arranged in the first layer (lower layer), and a character image may be arranged in the second layer (upper layer). Thus, an electronic file having a multi-layer function capable of performing a text search can be created.

  In addition, since the character image 42 has been subjected to the binarization processing (step S3), the contrast with the background image 43 is high and the visibility is high. Causes moire and the like from the characteristics of these scanner devices. As means for solving this problem, it is generally known that the occurrence of moire can be suppressed by performing a smoothing process on a scanned image.

  However, when the smoothing process is performed on the entire scanned image, there is a problem that characters are blurred and visibility is deteriorated.

  Therefore, after the character image 42 is extracted (step S4), the entire background image 43 or a region not recognized as the character image 42 in the background image 43 is selectively subjected to smoothing processing and γ correction. If image processing such as processing is performed, it is possible to enhance the visibility other than the character image 42.

  Further, since the background image 43 is generally composed of an image such as a photograph other than the character, the background image 43 may not require a high resolution like the character. Good.

FIG. 2 is a block diagram of an electrical connection of the image processing apparatus according to the embodiment of the present invention. FIG. 2 is a functional block diagram of the image processing apparatus. 5 is a flowchart illustrating a process executed by the image processing apparatus. 5 is a flowchart illustrating a process executed by the image processing apparatus. FIG. 4 is an explanatory diagram illustrating a process performed by the image processing device.

Explanation of reference numerals

1 image processing device 17 storage medium 20 program

Claims (12)

Extracting means for extracting a character portion of the image from the image data;
File creation means for separately saving, as one or a plurality of files, a character image that is the extracted image and a background image that is not filled with a predetermined image in a region where the character portion of the extracted image is extracted,
An image processing apparatus comprising: The image processing apparatus according to claim 1, wherein the extraction unit performs the extraction at a predetermined sampling interval when the image data is a color image. The image processing apparatus according to claim 1, wherein the file creating unit saves the character image as one or a plurality of binary images in the file when the image data is a color image. 4. The image according to claim 3, wherein the extraction unit extracts a character portion after binarizing the image data, extracts a color of a color image corresponding to the character portion, and specifies a character color. 5. Processing equipment. The image processing according to claim 1, wherein, when the image data is a color image, the file creating unit saves the character image in the file as a color image obtained by reducing the color of the character image. apparatus. 6. The file creation unit according to claim 1, wherein the extracted character image is lossless-compressed, and the extracted background image is lossy-compressed, each of which is compression-encoded and stored as the one or more files. The image processing device according to any one of the above. The image processing apparatus according to claim 6, wherein the file creating unit smoothes the extracted background image before the lossy compression. The file creator performs OCR processing on the extracted character image and converts the result of the OCR into text data of transparent text, the extracted character image, and the extracted background image as layers. The image processing apparatus according to claim 6, wherein the file is stored as a layer-managed file, and the text data layer is a higher layer than the character image layer. One or a plurality of images separately storing a character image which is an image obtained by extracting a character portion of an image from image data and a background image which is not filled with a predetermined image in a region where the character portion of the extracted image is extracted. An image processing apparatus comprising: an image creating unit that creates an image in which the character image is superimposed in an opaque color on an area where the character portion of the background image is extracted, for the file. An extraction process for extracting a character portion of the image from the image data;
A file creation process of separately saving, as one or a plurality of files, a character image that is the extracted image and a background image that is not filled with a predetermined image in a region where the character portion of the extracted image is extracted,
A computer-readable program that causes a computer to execute. One or a plurality of images separately storing a character image which is an image obtained by extracting a character portion of an image from image data and a background image which is not filled with a predetermined image in a region where the character portion of the extracted image is extracted. A computer-readable program for causing a computer to execute an image creation process of creating an image in which the character image is superimposed in an opaque color on an area where the character portion of the background image is extracted, for the file of (1). A storage medium storing the program according to claim 10.

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