JP2004297687A - Structure of image data, digital camera, and image data creation program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide structure of image data wherein a failure pixel can be corrected and portability is superior, a digital camera, and picture data creation program. <P>SOLUTION: In the digital camera, an object's optical image wherein imaging is performed by an optical system is subjected to photoelectric conversion with an image sensor, and a digital image showing the object is formed based on electric signals output from the image sensor. In the structure of image data recorded with the digital camera, a digital image data zone 43 which recorded a digital picture and a failure pixel data zone 42 which recorded failure pixel data showing failure pixel of the digital image are contained in one file. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of image data, a digital camera, and an image data creation program.
[0002]
[Prior art]
2. Description of the Related Art There is known a digital camera that photoelectrically converts an optical image of a subject formed by an optical system with an image sensor and creates a digital image representing the subject based on an electric signal output from the image sensor. Since the image sensor is composed of many light receiving cells such as one million or two million, even if there are some malfunctioning light receiving cells (defective cells) due to a problem such as a yield in manufacturing, the image sensor is used as it is. Often. When such an image sensor is used, the defective cell does not output a normal electric signal, so that a pixel corresponding to the defective cell in the created digital image becomes a defective pixel having a luminance different from the original.
[0003]
FIG. 4 is a schematic diagram showing a digital image in which a defective pixel exists. Since there is no correlation between the amount of light received by the defective cell and the electric signal output from the defective cell, for example, the pixel 30, which should have been bright, appears as a dark pixel as shown in the figure, thereby deteriorating the image quality of the digital image. become.
There is known a digital camera that outputs information specifying a defective cell together with the digital image in order to correct the image quality of the digital image that is degraded by such defective pixels (for example, see Patent Document 1). The electronic still camera (digital camera) disclosed in Patent Document 1 sets a defective pixel address (address of a defective cell) and the like of each CCD image sensor (image sensor) as individual information unique to the digital camera at the time of shipment from a factory, and sets a playback side. In, an output digital image is corrected based on individual information to obtain a high-quality image. For output to the reproduction side, the digital camera disclosed in Patent Document 1 records individual information in a defective pixel data area of a removable memory, and records digital information in a plurality of digital image data areas, so that the individual information is stored together with the digital image. Output.
[0004]
[Patent Document 1]
JP-A-6-86206 [0005]
[Problems to be solved by the invention]
The removable memory is used for temporarily storing a photographed digital image. In general, the digital image stored in the removable memory is often read by a personal computer and stored on a hard disk. In the digital camera of Patent Document 1, when a digital image is stored on a hard disk, it is necessary to perform correction at the time of reproduction, so that it is necessary to store individual information together with the digital image. In this case, according to the digital camera of Patent Document 1, there is a problem that portability is poor because individual information and a digital image must be separately stored. Specifically, for example, when saving the individual information and the digital image to the hard disk, the user must perform an operation of copying the individual information to the hard disk and an operation of copying the digital image to the hard disk. Poor portability because it must be. As a result, it is possible that reproduction or correction cannot be performed later due to an error such as forgetting to copy one.
[0006]
Further, according to the conventional digital camera, there is a problem that a defective pixel newly generated after shipment cannot be corrected based on the individual information. For example, if dust adheres to the lens or the light receiving cell, the pixel corresponding to the light receiving cell in which the shadow of the dust is reflected becomes a defective pixel. It can be said that the dust does not always adhere before the factory shipment, but rather is more likely to adhere after the shipment. However, since the conventional digital camera only aims to correct defective pixels caused by defective cells, the individual information is stored in the ROM at the time of shipment from the factory, and the information of the defective pixel due to dust attached after shipment is reflected in the individual information. I can't. For this reason, even if the individual information recorded in the removable memory is used, it is not possible to correct a defective pixel newly generated after shipment.
[0007]
The present invention has been made in view of such a problem, and has as its object to provide an image data structure, a digital camera, and an image data creation program that can correct defective pixels and have excellent portability.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the structure of image data according to the present invention is such that an optical image of a subject formed by an optical system is photoelectrically converted by an image sensor, and the subject is converted based on an electric signal output from the image sensor. A digital image data area recorded with a digital camera that creates a digital image representing a digital image, and a defective pixel data area recorded with defective pixel data representing defective pixels of the digital image. , Are included in one file. According to the structure of the image data, since the digital image and the defective pixel data are recorded in one file, the defective pixels of the digital image recorded in the image data are determined based on the defective pixel data recorded in the image data. Can be corrected. Further, the image data is excellent in portability because the digital image and the defective pixel data are included in one file.
[0009]
In order to achieve the above object, a digital camera according to the present invention includes an optical system that forms an optical image of a subject and an image that photoelectrically converts an optical image formed by the optical system and outputs an electric signal. A sensor, a processing unit for creating a digital image representing the subject based on the electric signal output from the image sensor, a digital image data area for recording the digital image, and defective pixel data representing defective pixels of the digital image. Image data recording means for recording image data including a defective pixel data area to be recorded in one file. According to this digital camera, image data capable of correcting defective pixels can be recorded. Also, the recorded image data is excellent in portability since it includes a digital image and defective pixel data in one file.
[0010]
Further, the digital camera according to the present invention is further characterized by further comprising input means for inputting defective pixel data. According to this digital camera, even if a new defective pixel is generated after shipment, correction is performed including the newly generated defective pixel by re-creating and inputting the defective pixel data. The defective pixel data that can be recorded can be recorded in the defective pixel data area. As a result, it is possible to correct a defective pixel including a defective pixel newly generated after shipment.
[0011]
Each function of the plurality of means provided in the present invention is realized by a hardware resource whose function is specified by the configuration itself, a hardware resource whose function is specified by a program, or a combination thereof. The functions of the plurality of means are not limited to those realized by hardware resources which are physically independent of each other.
Further, the present invention can be specified not only as an invention of an apparatus, but also as an invention of a program, an invention of a recording medium on which the program is recorded, and an invention of a method.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on a plurality of drawings.
FIG. 2 is a block diagram showing a hardware configuration of the digital still camera 1 as a digital camera according to one embodiment of the present invention.
The control unit 19 includes a CPU 19a, a flash memory 19b, and a work memory 19c. The CPU 19a controls the entire digital still camera 1 by executing a computer program stored in the flash memory 19b. The CPU 19a also functions as an image data recording unit by executing an image data creation program stored in the flash memory 19b. The flash memory 19b is a memory that stores an image data creation program, defective pixel data, various other programs and data, and the like. Various programs and data stored in the flash memory 19b may be downloaded from a predetermined server via a network and stored, or may be read from a computer-readable storage medium such as the removable memory 18 and stored. The work memory 19c is a memory for temporarily storing programs and data.
[0013]
The optical system 11 includes a lens, a diaphragm, and the like. The optical system 11 forms an optical image of a subject on a light receiving surface of the image sensor 12.
The image sensor 12 is an area image sensor including light receiving cells discretely arranged in a two-dimensional space and a charge transfer device such as a CCD (Charge Coupled Device). The image sensor 12 is driven by a sensor controller 13. The image sensor 12 accumulates a charge obtained by photoelectrically converting the optical image formed by the optical system 11 for each light receiving cell for a certain period of time, and outputs an electric signal corresponding to the amount of light received for each light receiving cell. Four complementary color filters of C (Cyan), M (Magenta), Y (Yellow) and G (Green) or primary color filters of R (Red), G (Green) and B (Blue) are provided on the light receiving surface. Thus, a color image can be formed.
[0014]
The processing unit 20 includes an A / D conversion unit (ADC) 14, a digital image processing unit 15, and a compression / decompression unit 16.
The ADC 14 quantizes the electric signal output from the image sensor 12 and converts it into a digital signal. Specifically, for example, the ADC 14 performs a process of reducing noise included in the electric signal, a process of adjusting a level of the electric signal by adjusting a gain, a quantization process, and the like.
[0015]
The digital image processing unit 15 performs image forming processing, white balance correction, γ correction, color space conversion, and the like on the digital signal output from the ADC 14, and performs R, G, B gradation values, Y , Cb, and Cr are output. Note that the image forming process here means that three tone values of RGB or YCbCr are provided for each pixel by interpolating the luminance information of one color output from the light receiving cell with the luminance information of different colors of the neighboring light receiving cells. This is a process of outputting a digital image having.
[0016]
The compression / decompression unit 16 compresses or decompresses a digital image. More specifically, the digital image is compressed by performing series conversion and entropy coding of the digital image, and decompressed by performing the inverse transform thereof. More specifically, the digital image is compressed using, for example, discrete cosine transform, wavelet transform, run-length coding, Huffman coding, or the like. The compressed digital image is temporarily stored in the work memory 19c.
[0017]
The input unit 17 as an input unit includes a card slot for connecting the removable memory 18, a memory controller, and the like. The input unit 17 is controlled by the control unit 19 and inputs the defective pixel data to the digital still camera 1 by reading the defective pixel data stored in the removable memory 18. The input unit of the present embodiment is input by reading defective pixel data from a removable memory. However, the input unit may be configured as a network interface and input by downloading via a network, or may be input by a USB interface. , And input by reading data from another USB device via a USB cable.
[0018]
The operation unit 22 includes a dial switch for setting a mode such as a shooting mode and an image display mode according to the rotation angle, a switch for calling a menu on an LCD (Liquid Crystal Display) 24, a switch for operating the menu, An imaging switch for instructing photographing is provided.
The LCD 24 functions as an electronic viewfinder in the shooting mode. The display controller 23 includes a frame buffer for storing a digital image for one screen of the LCD 24, and a display circuit for driving the LCD 24 based on the digital image stored in the frame buffer.
[0019]
The hardware configuration of the digital still camera 1 has been described above. Next, defective pixel data will be described.
The defective pixel data is data indicating which pixel among the pixels constituting the digital image is the defective pixel. The defective pixel data may be data representing whether or not the pixel is a defective pixel in binary for each pixel, or data representing only the coordinates of the defective pixel. If only the coordinates of the defective pixel are represented, the data amount of the defective pixel data can be reduced as compared with the case where the pixel is represented by a binary value. Further, when defective pixels are generated due to dust, defective pixels are concentrated in a specific area of the digital image. Therefore, the defective pixel data is obtained by centering the coordinates of the defective pixel at the center of the area in the digital image and the coordinates thereof. It may be data indicating a radius or a rectangular area including the set area. When the defective pixel is represented by the coordinates and the radius of the defective pixel at the center, or when the defective pixel is represented by coordinates of a rectangular area including the defective pixel coordinates, the data amount of the defective pixel data can be further reduced. Hereinafter, defective pixel data will be described in more detail by taking as an example a case where only the coordinates of a defective pixel are represented.
[0020]
FIG. 3A is a schematic diagram showing a plurality of pixels constituting a digital image, and FIG. 3B is a schematic diagram showing defective pixel data. Here, the pixels shown in FIG. 3A are pixels constituting a digital image representing a white plate-like subject, the pixels represented by white frames represent normal pixels, and the black pixels 30 represent defective pixels. ing. One pixel of the digital image basically corresponds to one light receiving cell. However, since one light receiving cell can output only one color of the luminance information of RGB or YCbCr, the luminance information of the pixel uses the luminance information of the corresponding light receiving cell for any one of the colors, The color is interpolated with luminance information of different colors of the neighboring light receiving cells. Thus, as described above, one pixel can have three gradation values of RGB or YCbCr. That is, one light receiving cell corresponds to a plurality of pixels, and a plurality of defective pixels are generated by one defective cell or by dust being reflected in one light receiving cell. The defective pixel data shown in FIG. 3B stores the X coordinate and the Y coordinate of the defective pixel shown in FIG. 3A, thereby uniquely identifying which pixel in the digital image is the defective pixel. can do. The defective pixel data is created by subjecting a digital image created by the digital still camera 1 to image processing by a personal computer. The created defective pixel data is stored in the removable memory 18, read by the input unit 17, and input to the digital still camera 1. Specifically, for example, the digital still camera 1 creates a digital image representing a white flat object as shown in FIG. 3A, and outputs the digital image to a personal computer. The reason why the digital image representing the white plate-shaped object is created here is to make it easy to distinguish normal pixels from defective pixels. The personal computer determines that the luminance of each pixel of the digital image is equal to or higher than a predetermined threshold value, and determines that the pixel is a defective pixel if the luminance is less than the threshold value. The coordinates of the defective pixel are determined as shown in FIG. Add to pixel data. In general, the luminance of a pixel is represented by 256 gradations, and the luminance of R, G, and B is closer to 255 for a white pixel, and to 0 for a darker pixel. When a white plate-shaped subject is photographed, the luminance of all the pixels should originally be close to 255, but the luminance of the defective pixel is close to 0 because the luminance is low. This makes it possible to determine whether or not the pixel is a defective pixel. The defective pixel data may be created by a method other than the image processing. For example, a digital image representing an arbitrary subject is enlarged and displayed on a display device provided in a personal computer, and a user visually confirms a defective pixel, and a pixel clicked by a user with a mouse or an area specified by a mouse with an area. The included pixels may be determined to be defective pixels. The defective pixel data can be input at any time. For example, if dust adheres after shipment, the defective pixel data can be recreated by a personal computer and input to the digital still camera 1 again. Therefore, the digital still camera 1 can record in the defective pixel data area defective pixel data capable of correcting a defective pixel due to dust attached after shipping. As a result, even if a new defective pixel occurs after shipment, it is possible to correct the defective pixel and reproduce a high-quality image.
[0021]
Next, the structure of a digital image file as image data will be described.
FIG. 1 is a schematic diagram showing the structure of a digital image file. As shown, the digital image file includes a header area 41, a defective pixel data area 42, a digital image data area 43, and the like. The defective pixel data area 42 is an area where defective pixel data is recorded, and the digital image data area 43 is an area where a digital image is recorded. The header area 41 is an area in which a pointer indicating the start address of the defective pixel data area 42, a pointer indicating the start address of the digital image data area 43, and other header information such as creation date and image size are recorded. At the time of reproduction, by reading a pointer from the header area 41, the start address of the defective pixel data area 42 or the digital image data area 43 can be specified, whereby the defective pixel data and the digital image can be read.
[0022]
Next, the operation of the digital still camera 1 will be described. It is assumed that the defective pixel data has already been input to the digital still camera 1 and stored in the flash memory 19b.
When the imaging switch is turned on in a state where the dial switch is set to the photographing mode, an optical image of the subject is formed on the image sensor 12 by the optical system 11, and an electric signal correlated with the density of the optical image is processed by the processing unit 20. Is output to
[0023]
The output electric signal is subjected to predetermined processing by the ADC 14 and the digital image processing unit 15 of the processing unit 20, and a digital image representing the subject is created.
The created digital image is output to the compression / expansion unit 16, and the compression / expansion unit 16 compresses the output digital image and stores it in the work memory 19c.
The CPU 19a executes the image data creation program stored in the flash memory 19b, reads the digital image stored in the work memory 19c and the defective pixel data stored in the flash memory 19b, and reads the digital image and the defective pixel. A digital image file in which data is stored is created. After creation, the digital image file is output to the input unit 17.
[0024]
The input unit 17 stores the digital image file in the removable memory 18. For example, when storing a digital image file on a hard disk, the removable memory 18 is removed by a user and connected to a personal computer. After the connection, the user saves the digital image file on the hard disk using a personal computer. During reproduction, defective pixels of the digital image are corrected based on the defective pixel data recorded in the digital image file in which the digital image is recorded, and are displayed on a display device provided in the personal computer.
[0025]
According to the digital image file described above, since the digital image and the defective pixel data are recorded in one digital image file, the defective pixels of the digital image recorded in the digital image file are recorded in the digital image file. Correction can be performed based on defective pixel data. When a digital image and defective pixel data are stored on a hard disk, the digital image and the defective pixel data can be stored by storing the digital image file. Therefore, it is necessary to store the digital image and the defective pixel data separately. And there are fewer operations to save. In addition, the number of operations for moving to another directory after saving is similarly reduced. In addition, there is no case where reproduction or correction cannot be performed later due to forgetting to copy one of them. Therefore, the digital image file of the present embodiment is excellent in portability. Further, according to the digital image file of the present embodiment, there is an effect that the trouble of management is reduced. Since the defective pixel data is information unique to the digital camera, appropriate correction cannot be performed even if a digital image created by one digital camera is corrected by defective pixel data of another digital camera. Therefore, when there are a plurality of digital cameras and the digital images created by them are stored on the same hard disk, the digital images must be managed in association with the defective pixel data used for correcting the defective pixels of the digital images. No. If the digital image and the defective pixel data are recorded in one digital image file, such management can be reduced.
[0026]
In this embodiment, the case where the defective pixel data is created by a personal computer has been described as an example. However, the digital still camera 1 may create the defective pixel data.
In the present embodiment, a digital still camera has been described as an example, but the present invention may be applied to a digital video camera.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a structure of image data.
FIG. 2 is a block diagram illustrating a hardware configuration of the digital camera.
FIG. 3A is a schematic diagram illustrating pixels forming a digital image, and FIG. 3B is a schematic diagram illustrating defective pixel data.
FIG. 4 is a schematic diagram showing a digital image in which a defective pixel exists.
[Explanation of symbols]
Reference Signs List 1 digital still camera (digital camera), 11 optical system, 12 image sensor, 17 input unit (input means), 19 control unit, 20 processing unit, 42 defective pixel data area, 43 digital image data area

Claims (4)

Structure of image data recorded by a digital camera that photoelectrically converts an optical image of a subject formed by an optical system by an image sensor and creates a digital image representing the subject based on an electric signal output from the image sensor And
A digital image data area in which a digital image is recorded;
A defective pixel data area in which defective pixel data representing defective pixels of the digital image is recorded;
Is included in one file. An optical system that forms an optical image of the subject,
An image sensor that photoelectrically converts an optical image formed by the optical system and outputs an electric signal,
A processing unit that creates a digital image representing the subject based on the electric signal output from the image sensor,
Image data recording means for recording image data including a digital image data area for recording a digital image and a defective pixel data area for recording defective pixel data representing defective pixels of the digital image in one file;
A digital camera comprising: 3. The digital camera according to claim 2, further comprising input means for inputting defective pixel data. An optical image of a subject formed by an optical system is photoelectrically converted by an image sensor, and a control unit of a digital camera that creates a digital image representing the subject based on an electric signal output from the image sensor,
Image data recording means for recording image data including a digital image data area for recording a digital image and a defective pixel data area for recording defective pixel data representing defective pixels of the digital image in one file;
An image data creation program characterized by functioning as:

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