JP2011147012A - Image display device, and method of displaying image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that a false color may be generated when displaying monochrome image data. <P>SOLUTION: A method of displaying an image includes a step of determining whether or not image data to be displayed is monochrome image data (S820) and a step of carrying out high-frequency reduction processing for reducing high-frequency components to the monochrome image data when it is determined that the image data to be displayed is monochrome image data (S830). By displaying the monochrome image data (S840) subjected to high-frequency reduction processing, the generation of the false color can be suppressed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image display device and an image display method for displaying monochromatic image data.

  In order to reproduce a grainy feeling like a silver salt photograph, a technique for superimposing a noise pattern on image data has been proposed. In the technique described in Patent Document 1, random numbers are generated in units of pixels, and frequency filter processing and scale change are performed to superimpose granularity with an expected granularity on an image. In the technique described in Patent Document 2, a granular pattern is calculated by subtracting a smoothed image from an exposure image obtained from a uniformly exposed color film.

US Pat. No. 5,641,596 Japanese Patent Laid-Open No. 11-85955

  In general, in a natural image, the correlation between adjacent pixels is high. Therefore, even if each pixel of the image data is directly associated with the pixel of the display panel and displayed using a display method that displays only the color information of the image data corresponding to the color filter of the display panel, there is no sense of incongruity, and It is possible to display an image with sufficient resolution. However, in a monochrome image with graininess added, the correlation between the luminance values of adjacent pixels is low, and the difference in luminance values is large. Therefore, when displayed in the same display method, the luminance of the pixel of interest on the display panel is displayed. The value and the luminance value of a pixel adjacent to the color filter may be greatly different from each other, which may cause a false color that should not exist.

  An object of the present invention is to provide a technique for displaying single-color image data so that false colors do not occur.

  An image display apparatus according to an aspect of the present invention includes a determination unit that determines whether image data to be displayed is single-color image data, and high-frequency reduction that performs high-frequency reduction processing that reduces high-frequency components on the image data. When the processing unit and the determination unit determine that the image data to be displayed is single color image data, the high frequency reduction processing unit is controlled so that the high frequency reduction process is performed on the single color image data. A control unit; and a display unit that displays the monochromatic image data subjected to the high-frequency reduction process.

  An image display method according to another aspect of the present invention is an image display method for displaying image data on a display unit, the step of determining whether or not the image data to be displayed is monochromatic image data, Determining that the image data is monochrome image data, performing a high frequency reduction process for reducing high frequency components to the monochrome image data, displaying monochromatic image data subjected to the high frequency reduction process, and Is provided.

  According to the present invention, it is possible to suppress generation of false colors when displaying monochrome image data.

It is a block diagram which shows the structure of the digital still camera to which the image display apparatus in 1st Embodiment is applied. It is a flowchart which shows the main processing flow performed with the digital still camera to which the image display apparatus which concerns on 1st Embodiment is applied. It is a flowchart which shows the detail of still image photography and image processing. It is a flowchart which shows the detail of a live view display, video recording, and image processing. It is a flowchart which shows the detail of a reproduction | regeneration process. It is a flowchart which shows the detail of a developing process. It is a flowchart which shows the detail of a LCD display process. It is a figure for demonstrating the method to display image data on LCD. It is a flowchart which shows the detail of the LCD display process performed by the image display apparatus in 2nd Embodiment. 14 is a flowchart illustrating details of an LCD display process performed by the image display device according to the third embodiment. It is a figure for demonstrating the process displayed on LCD after performing the averaging process of 3 pixels of horizontal directions with respect to monochrome image data. It is a flowchart which shows the detail of the LCD display process performed by the image display apparatus in 4th Embodiment. After processing to reduce the size of monochromatic image data to one third of the size in the horizontal direction, it performs processing to enlarge it three times in the horizontal direction by the nearest neighbor interpolation method, and then the LCD It is a figure for demonstrating the process displayed on this.

<First Embodiment>
FIG. 1 is a block diagram illustrating a configuration of a digital still camera to which the image display apparatus according to the first embodiment is applied. The digital still camera shown in FIG. 1 includes a camera body 1 and an interchangeable lens 2.

  The interchangeable lens 2 includes a lens 1010, a flash memory 1011, a microcomputer 1012, a driver 1013, and a diaphragm 1014. The interchangeable lens 2 is communicably connected to the camera body 1 via the I / F 999.

  The camera body 1 includes a mechanical shutter 101, an image sensor 102, an analog processing unit 103, an analog / digital conversion unit 104 (hereinafter referred to as A / D conversion unit 104), a bus 105, an SDRAM 106, and an image processing unit 107. An AE processing unit 108, an AF processing unit 109, an image compression / decompression unit 110, a memory interface 111 (hereinafter referred to as a memory I / F 111), a recording medium 112, an LCD driver 113, an LCD 114, and a microcomputer 115. An operation unit 116, a flash memory 117, a noise pattern generation unit 118, and an image addition unit 119.

  The lens 1010 focuses the optical image of the subject on the image sensor 102. The lens 1010 may be a single focus lens or a zoom lens.

  The microcomputer 1012 is connected to the I / F 999, the flash memory 1011 and the driver 1013. The microcomputer 1012 reads and writes information stored in the flash memory 1011 and controls the driver 1013. Information stored in the flash memory 1011 includes data on the focal length of the interchangeable lens 2 and the like.

  The microcomputer 1012 can further communicate with the microcomputer 115 via the I / F 999, transmits various information to the microcomputer 115, and receives information such as an aperture value from the microcomputer 115.

  In response to an instruction from the microcomputer 1012, the driver 1013 drives the lens 1010 to change the focal length and focus position, and drives the aperture 1014. The aperture 1014 is provided in the vicinity of the lens 1010 and adjusts the amount of light of the subject.

  The mechanical shutter 101 is driven in response to an instruction from the microcomputer 115 to control the time for exposing the subject to the image sensor 102.

  The image sensor 102 is an image sensor in which a Bayer array color filter is arranged in front of a photodiode constituting each pixel. The Bayer array has a line in which R pixels and G (Gr) pixels are alternately arranged in a horizontal direction, and a line in which G (Gb) pixels and B pixels are alternately arranged, and the two lines are further divided. It is configured by alternately arranging in the vertical direction. The imaging element 102 receives the light collected by the lens 1010 by a photodiode that constitutes a pixel and performs photoelectric conversion, and outputs the amount of light to the analog processing unit 103 as a charge amount. The image sensor 102 may be a CMOS type or a CCD type.

  The analog processing unit 103 performs waveform shaping on the electrical signal (analog image signal) read from the image sensor 102 while reducing reset noise and the like, and further increases the gain so that the target brightness is obtained. . The A / D conversion unit 104 converts the analog image signal output from the analog processing unit 103 into a digital image signal (hereinafter referred to as image data).

  A bus 105 is a transfer path for transferring various data generated in the digital camera to each unit in the digital camera. The bus 105 includes an A / D conversion unit 104, an SDRAM 106, an image processing unit 107, an AE processing unit 108, an AF processing unit 109, an image compression / decompression unit 110, a memory I / F 111, an LCD driver 113, and the like. The microcomputer 115, the noise pattern generation unit 118, and the image addition unit 119 are connected.

  The image data output from the A / D conversion unit 104 is temporarily stored in the SDRAM 106 via the bus 105. The SDRAM 106 is a storage in which various data such as image data obtained by the A / D conversion unit 104 and image data processed by the image processing unit 107, the image compression / decompression unit 110, and the image addition unit 119 are temporarily stored. Part.

  The image processing unit 107 includes an optical black subtraction unit 1071 (hereinafter referred to as OB subtraction unit 1071), a white balance correction unit 1072 (hereinafter referred to as WB correction unit 1072), a synchronization processing unit 1073, a color matrix calculation unit 1074, a gamma / color reproduction. The image processing apparatus includes a processing unit 1075, an edge enhancement processing unit 1076, and a noise reduction processing unit 1077 (hereinafter referred to as NR processing unit 1077), and performs various image processing on the image data read from the SDRAM 106.

  The OB subtraction unit 1071 performs optical black subtraction processing (hereinafter referred to as OB subtraction processing) on the image data. The OB subtraction process is a process of subtracting an optical black value (hereinafter referred to as an OB value) caused by a dark current of the image sensor 102 from a pixel value of each pixel constituting image data.

  The WB correction unit 1072 performs a process of correcting the white balance by multiplying the image data by a white balance gain corresponding to the white balance mode. The white balance mode can be set by the user in accordance with a light source such as sunny weather, cloudy weather, a light bulb, and a fluorescent light.

  The synchronization processing unit 1073 performs a process of synchronizing image data based on the Bayer array into image data including R, G, and B information per pixel. The color matrix calculation unit 1074 corrects the color of the image data by performing linear conversion on the image data by multiplying the color matrix coefficient. The gamma / color reproduction processing unit 1075 performs gamma correction processing and color reproduction processing for changing the color of an image.

  The edge enhancement processing unit 1076 uses a bandpass filter to extract edge components from the image data, multiply the extracted edge component data by a coefficient corresponding to the degree of edge enhancement, and then add it to the image data. Then, processing for enhancing the edge of the image data is performed.

  The NR processing unit 1077 performs processing for reducing noise by processing using a filter that reduces high frequency, coring processing, and the like.

  The image data after each processing is performed by the image processing unit 107 is stored in the SDRAM 106.

  The AE processing unit 108 calculates subject luminance from the image data. The data for calculating the subject brightness may be an output of a dedicated photometric sensor. The AF processing unit 109 extracts a high-frequency component signal from the image data, and acquires a focus evaluation value by AF (Auto Focus) integration processing.

  The noise pattern generation unit 118 generates noise pattern data to be added to the image data. Specifically, noise pattern data having the same size as the image data to be added is generated based on the noise pattern data stored in the flash memory 117. This noise pattern data is data of a granular pattern resembling the granular feeling due to silver salt particles. The generated noise pattern data is stored in the SDRAM 106.

  The image adder 119 adds the image data stored in the SDRAM 106 and the noise pattern data. The image data obtained by adding the noise pattern data is stored in the SDRAM 106.

  When still image data is recorded, the image compression / decompression unit 110 reads the image data from the SDRAM 106, compresses the read image data according to the JPEG compression method, and temporarily stores the compressed JPEG image data in the SDRAM 106. The microcomputer 115 creates a JPEG file by adding a JPEG header necessary for constructing a JPEG file to the JPEG image data stored in the SDRAM 106, and sends the created JPEG file via the memory I / F 111. To the recording medium 112.

  The image compressing / decompressing unit 110 also reads out the moving image data from the SDRAM 106 when recording the moving image data. The compressed moving image data is temporarily stored in the SDRAM 106 after being compressed according to the H.264 system. The image compression / decompression unit 110 further performs a process of decompressing (decompressing) the compressed data based on a command from the microcomputer 115.

  The recording medium 112 is, for example, a recording medium including a memory card that can be attached to and detached from the camera body 1, but is not limited thereto.

  The LCD driver 113 includes a display image processing unit 120 and causes the LCD 114 to display an image. When the image displayed on the LCD 114 is a single color image, the display image processing unit 120 performs a process of reducing the high frequency component of the image. That is, when the display image is a single color image, the image after the high frequency reduction processing is displayed on the LCD 114, and when the display image is a non-monochromatic image, the image not subjected to the high frequency reduction processing is displayed on the LCD 114. As will be described later, the LCD 114 is a display unit that displays a part of the data of each pixel constituting the image data.

  Here, the display of the image includes a REC view display that displays image data immediately after shooting for a short time, a playback display of a JPEG file recorded on the recording medium 112, and a display of a moving image such as a live view display. . When reproducing the compressed data recorded on the recording medium 112, the image compression / decompression unit 110 reads out the compressed data recorded on the recording medium 112, performs decompression (decompression) processing, and then temporarily decompresses the decompressed data. It is stored in the SDRAM 106. The LCD driver 113 reads the decompressed data from the SDRAM 106, converts the read data into a video signal, and then outputs it to the LCD 114 for display.

  The microcomputer 115 having a function as a control unit comprehensively controls various sequences of the digital camera body 1. An operation unit 116 and a flash memory 117 are connected to the microcomputer 115.

  The operation unit 116 is an operation member such as a power button, a release button, a moving image button, a playback button, and various input keys. When one of the operation members of the operation unit 116 is operated by the user, the microcomputer 115 executes various sequences according to the user's operation. The power button is an operation member for instructing power on / off of the digital camera. When the power button is pressed, the power of the digital camera is turned on. When the power button is pressed again, the digital camera is turned off. The release button has a two-stage switch of a first release switch and a second release switch. When the release button is pressed halfway and the first release switch is turned on, the microcomputer 115 performs a shooting preparation sequence such as AE processing and AF processing. Further, when the release button is fully pressed and the second release switch is turned on, the microcomputer 115 performs shooting by executing a shooting sequence.

  The playback button is a button for causing the LCD 114 to display a still image or a moving image obtained by shooting.

  The movie button is a button for starting and ending movie shooting. Since the moving image is not yet shot in the initial state, when the moving image button is pressed in this state, moving image shooting starts. When the moving image button is pressed during moving image shooting, moving image shooting ends. Therefore, each time the moving image button is pressed, the start and end of moving image shooting are repeated alternately.

  The flash memory 117 includes various parameters necessary for operation of the digital camera such as a white balance gain, a color matrix coefficient, and a low-pass filter coefficient according to the white balance mode, noise data of a granular pattern resembling a granular feeling due to silver salt particles, and A serial number for specifying a digital still camera is stored. The flash memory 117 also stores various programs executed by the microcomputer 115. The microcomputer 115 reads parameters necessary for various sequences from the flash memory 117 according to a program stored in the flash memory 117, and executes each process.

  FIG. 2 is a flowchart showing a main processing flow performed by the digital still camera to which the image display apparatus according to the first embodiment is applied. When the user presses the power button to turn on the digital still camera, the microcomputer 115 starts the process of step S201.

  In step S201, the recording flag is initialized to off. The recording flag is a flag that is turned on during moving image shooting and turned off when no moving image is shot.

  In step S202, it is determined whether or not the playback button has been operated by the user. If it is determined that the play button has been operated, the process proceeds to step S203. If it is determined that the play button has not been operated, the process proceeds to step S204.

  In step S203, processing for reproducing a still image or a moving image obtained by shooting is performed. Details of the reproduction process will be described later with reference to FIG.

  In step S204, it is determined whether or not the video button has been operated by the user. If it is determined that the movie button has been operated, the process proceeds to step S205. If it is determined that the movie button has not been operated, the process proceeds to step S206.

  In step S205, the recording flag is reversed, and the process proceeds to step S206. As described above, every time the video button is pressed, the video recording start and end are alternately repeated. Therefore, in this step, if the recording flag is off, it is on, and if it is on, Turn off and invert the recording flag.

  In step S206, it is determined whether the recording flag is on. If it is determined that the recording flag is on, the process proceeds to step S211. If it is determined in step S211 that moving image recording is in progress, image processing and image compression are performed on the image data of the moving image based on the image signal from the image sensor 102 and then recorded on the recording medium 112. If it is determined that the moving image recording is not in progress, a live view display for determining a subject composition and shutter timing in still image shooting is performed. Details of live view display, moving image shooting, and image processing in step S211 will be described later with reference to FIG.

  On the other hand, if it is determined in step S206 that the recording flag is off, the process proceeds to step S207. In step S207, it is determined whether or not the user has pressed the release button halfway to turn on the first release switch. If it is determined that the first release switch is turned on, the process proceeds to step S208.

  In step S208, AF processing is performed. Specifically, first, the AF processing unit 109 calculates a focus evaluation value. The microcomputer 115 issues a command for driving the lens 1010 to the driver 1013 based on the focus evaluation value. Based on this command, the driver 1013 drives the lens 1010 to change the focal length and the focus position.

  If the first release switch is not turned on in step S207, or if the first release switch remains on, the process proceeds to step S209. In step S209, it is determined whether or not the release button is fully pressed by the user and the second release switch is turned on. If it is determined that the second release switch is turned on, the process proceeds to step S210. If it is determined that the second release switch is not turned on, the process proceeds to step S211.

  In step S210, still image shooting and image processing are performed. Details of the still image shooting / image processing will be described later with reference to FIG.

  In step S212, it is determined whether the power of the digital still camera is turned off. If it is determined that the power is not turned off, the process returns to step S202, and the above-described processing is performed. On the other hand, when the power button is pressed by the user and the power is turned off, the process of the flowchart is ended.

  As described above, in the main flow in the present embodiment, the still image shooting mode is set in the initial setting. In this state, steps S202 → S204 → S206 → S207 → S209 → S211 → S212 → S202 are sequentially executed. Perform live view display. If the release button is pressed halfway during live view display, an AF operation is performed in step S208, and if the release button is fully pressed, a still image is shot in step S210. When the moving image button is pressed, the recording flag is turned on in step S205, and moving image shooting is continued by repeatedly executing steps S206 → S211 → S212 → S202 → S204 → S206. When the moving image button is pressed again in this state, the recording flag is turned off in step S205, and the flow returns to the still image flow described above.

  FIG. 3 is a flowchart showing details of the process in step S210 of the flowchart shown in FIG. 2, that is, details of still image shooting / image processing.

  In step S310, AE processing is performed. Specifically, the AE processing unit 108 calculates subject brightness, and refers to the exposure condition determination table stored in the flash memory 117 based on the calculated subject brightness, so that the ISO sensitivity at the time of shooting, the aperture , And determine the shutter speed.

  In step S320, shooting is performed. The shooting (still image shooting) is the same as a conventionally used method. The driver 1013 drives the aperture 1014 so as to achieve a set aperture value based on an instruction from the microcomputer 1012. Then, based on the determined shutter speed, shooting is performed by controlling the mechanical shutter 101 to obtain image data corresponding to the determined ISO sensitivity.

  In step S330, various image processes are performed on the image data (Bayer data) obtained in step S320 to perform development processing for conversion into luminance (Y) and color difference (Cb, Cr) signal data. Details of the development processing will be described later with reference to FIG.

  In step S340, the LCD driver 113 causes the LCD 114 to display image data obtained by shooting for a short time. This display is a so-called REC view display. Details of this display processing will be described later with reference to FIG.

  In step S350, the image compression / decompression unit 110 performs JPEG compression on the image data, adds header information such as the image size and shooting conditions, and generates a JPEG file.

  In step S360, the JPEG file generated in step S350 is recorded on the recording medium 112 via the memory I / F 111.

  FIG. 4 is a flowchart showing details of the process in step S211 of the flowchart shown in FIG. 2, that is, live view display / moving image capturing / image processing.

  In step S410, an AE process is performed. This process is the same as the process of step S310 in the flowchart shown in FIG.

  In step S420, shooting is performed. The shooting (moving image shooting) is the same as a conventionally used method. That is, shooting is performed by controlling a so-called electronic shutter based on the determined aperture, shutter speed, and ISO sensitivity.

  In step S430, various image processing is performed on the image data (Bayer data) obtained in step S420 to perform development processing for conversion into luminance (Y) and color difference (Cb, Cr) signal data. Details of the development processing will be described later with reference to FIG.

  In step S440, the LCD driver 113 displays image data on the LCD 114. This display is a so-called live view display. Details of this display processing will be described later with reference to FIG.

  In step S450, it is determined whether a moving image is being recorded. If the recording flag is off, it is determined that the moving image is not being recorded, and the processing of this flowchart is terminated. If the recording flag is on, it is determined that the moving image is being recorded, and step S460 is performed. Proceed to

  In step S460, a moving image file is generated and recorded on the recording medium 112. That is, the image compression / decompression unit 110 compresses the image data according to the format of the moving image file, adds predetermined header information, and generates a moving image file. The compression format of the moving image file includes “H.264”, “Motion JPEG”, “MPEG”, and the like. Then, the generated moving image file is recorded on the recording medium 112 via the memory I / F 111.

  FIG. 5 is a flowchart showing details of the process in step S203 of the flowchart shown in FIG. 2, that is, the reproduction process.

  In step S500, an image file to be displayed on the LCD 114 is determined based on the operation of the operation unit 116 by the user. When the user presses the play button, the moving image file and still image file recorded on the recording medium 112 are displayed as a list (thumbnail display) on the LCD 114. For video files, the first frame image is displayed as a thumbnail. The user selects a file to be displayed on the LCD 114 by operating a cross key included in the operation unit 116. The selected file is determined as an image file to be displayed on the LCD 114.

  In step S510, it is determined whether the image file determined in step S500 is a moving image file. If it is determined that the file is not a moving image file but a still image file, the process proceeds to step S580.

  In step S580, the image compression / expansion unit 110 acquires the image data to be displayed on the LCD 114 by selecting and expanding the still image file determined in step S500 from the files recorded on the recording medium 112. .

  In step S590, the LCD driver 113 causes the LCD 114 to display the image data acquired in step S580. Details of this display processing will be described later with reference to FIG.

  On the other hand, if it is determined in step S510 that the image file determined in step S500 is a moving image file, the process proceeds to step S520. In step S520, information on the number of frames included in the header information of the moving image file is acquired.

  In step S530, a parameter N for counting the number of frames is set to an initial value of 1.

  In step S540, the image compression / decompression unit 110 selects the moving image file determined in step S500 from the files recorded on the recording medium 112, and performs a process of expanding the Nth frame image data.

  In step S550, the LCD driver 113 causes the LCD 114 to display the image data of the Nth frame acquired in step S540. Details of this display processing will be described later with reference to FIG.

  In step S560, 1 is added to parameter N, and the process proceeds to step S570.

  In step S570, it is determined whether the parameter N is larger than the number of frames of the moving image file. If it is determined that the parameter N is equal to or less than the number of frames of the moving image file, the process returns to step S540 to develop the image data of the next frame (step S540) and display it on the LCD 114 (step S550). On the other hand, when it is determined that the parameter N is larger than the number of frames of the moving image file, the reproduction process is terminated.

  FIG. 6 is a flowchart showing details of the process in step S330 in the flowchart shown in FIG. 3 and the process in step S430 in the flowchart shown in FIG. 4, that is, the development process.

  In step S610, the OB subtraction unit 1071 performs OB subtraction processing for subtracting the OB value obtained at the time of imaging from the image data obtained by imaging.

  In step S620, the WB correction unit 1072 performs a process of correcting the white balance by multiplying the image data subjected to the OB subtraction process by a white balance gain corresponding to the white balance mode. Note that the white balance mode can be set for each shooting by the user operating an input key included in the operation unit 116. The microcomputer 115 sets the white balance mode based on the operation of the operation unit 116 by the user. When the digital still camera has an auto white balance function that automatically adjusts the white balance, the microcomputer 115 automatically sets a white balance mode in accordance with the light source at the time of shooting.

  In step S630, the synchronization processing unit 1073 performs synchronization processing on the image data on which the white balance correction processing has been performed.

  In step S640, the color matrix calculation unit 1075 performs color matrix calculation on the image data on which the synchronization processing has been performed, by multiplying the color matrix coefficient corresponding to the white balance mode.

  In step S650, the gamma / color reproduction processing unit 1074 performs gamma correction processing and color reproduction processing for changing the color of the image on the image data on which the color matrix calculation has been performed.

  In step S660, the edge enhancement processing unit 1076 performs edge enhancement processing on the image data that has been subjected to gamma correction processing and color reproduction processing.

  In step S670, the NR processing unit 1077 performs noise reduction processing on the image data on which the edge enhancement processing has been performed. In the noise reduction process, a coring process based on the coring parameter or a process using a filter that reduces high frequency is performed based on the noise reduction parameter (hereinafter referred to as NR parameter).

  In step S680, it is determined whether or not the shooting mode is a monochrome film mode. The monochrome film mode is a shooting mode for generating an image like a monochrome photograph taken with a monochrome film. If it is determined that the shooting mode is the monochrome film mode, the process proceeds to step S690.

  In step S690, the noise pattern generation unit 118 generates noise pattern data to be added to the image data. Specifically, noise pattern data having the same size as the image data to be added is generated based on the noise pattern data stored in the flash memory 117.

  In step S700, the image adding unit 119 adds the image data subjected to the processing from step S610 to step S670 and the noise pattern data generated in step S690.

  In step S710, the gamma / color reproduction processing unit 1074 sets the color difference component to 0 and performs high contrast gamma processing on the image data to which the noise pattern is added.

  On the other hand, if it is determined in step S680 that the shooting mode is not the monochrome film mode, the process proceeds to step S720. In step S720, it is determined whether the shooting mode is a sepia mode. The sepia mode is a shooting mode that generates a sepia tone image. If it is determined that the shooting mode is not the sepia mode, the development process is terminated. If it is determined that the shooting mode is the sepia mode, the process proceeds to step S730.

  In step S730, the gamma / color reproduction processing unit 1074 performs processing for fixing the color difference signals Cb and Cr to predetermined values (for example, Cb = −10, Cr = 12) in order to generate a sepia tone image.

  7 shows the details of the process of step S340 in the flowchart shown in FIG. 3, the process of step S440 in the flowchart shown in FIG. 4, and the processes in steps S550 and S590 of the flowchart shown in FIG. It is a flowchart to show.

  In step S810, the size of the image data to be displayed is resized in accordance with the display size of the LCD 114. This processing may be performed by the image processing unit 107 or the microcomputer 115.

  In step S820, it is determined whether the display target image is a single color image. A monochromatic image is an image whose hue is limited within a predetermined range, and is, for example, a monochrome image or a sepia tone image. This determination is made based on header information attached to the image data. In this embodiment, when the display target image is a monochrome image or a sepia image, it is determined that the image is a single color image. If it is determined that the image to be displayed is not a monochrome image, the process proceeds to step S840. If it is determined that the image to be displayed is a monochrome image, the process proceeds to step S830.

  In step S830, the display image processing unit 120 performs horizontal low-pass filter processing on the monochrome image to be displayed. For example, in the case of 5 taps, the low-pass filter coefficient is 9/128, 32/128, 46/128, 32/128, 9/128 in the horizontal direction. However, the number of taps and the low-pass filter coefficient are not limited to the above numerical values. By performing the low-pass filter process in the horizontal direction, it is possible to reduce the luminance difference between adjacent pixels and to suppress the generation of false colors when displaying a monochrome image on the LCD 114.

  In step S840, the processed image data is displayed on the LCD 114 by the LCD driver 113. The processed image data is image data that has been subjected to the horizontal low-pass filter processing in step S830 in the case of a monochrome image, and is image data that has been resized in step S810 for images other than the monochrome image.

  FIG. 8 is a diagram for explaining a method of displaying image data on the LCD 114. Here, the pixel arrangement of the LCD 114 will be described as a delta arrangement, but is not limited to a delta arrangement.

  One pixel of the display image data includes R, G, and B data. On the other hand, one pixel of the LCD 114 includes only one of R, G, and B data. Therefore, when displaying the display image data on the LCD 114, the same data as the color filter color of each pixel of the LCD 114 is displayed from the data of each pixel of the display image data. For example, since the pixel 81 of the LCD 114 in FIG. 8 corresponds to the R filter, R data is displayed among the RGB data of the pixel 85 of the display image data. Further, since the pixel 82 of the LCD corresponds to the G filter, the G data is displayed among the RGB data of the pixel 86 of the display image data.

  Here, when the display image is a natural image, since a plurality of colors are used and the correlation between the pixels is high, the display method described with reference to FIG. While maintaining the above, it is possible to display the false color inconspicuously. However, when displaying a monochrome image with a noise pattern such as a granular pattern resembling the graininess of silver salt particles, the correlation between the luminance values of adjacent pixels is low and the difference in luminance values is large. Colors can occur.

  However, in the image display device according to the first embodiment, since the horizontal low-pass filter process is performed on the monochromatic image to which the noise pattern is added, generation of false colors can be achieved by increasing the correlation between the luminance values of adjacent pixels. Can be suppressed.

  As described above, according to the image display device in the first embodiment, it is determined whether or not the image data to be displayed is single-color image data. After processing, it is displayed on the LCD 114. As a result, the difference in luminance value between adjacent pixels of the monochromatic image is reduced, so that the occurrence of false colors can be suppressed when displayed on the LCD 114.

  In addition, when the image data to be displayed is non-monochromatic image data, the high-frequency reduction process performed on the monochromatic image data is not performed, so that the display image quality of the non-monochromatic image is not degraded.

<Second Embodiment>
In the image display device according to the first embodiment, when the image displayed on the LCD 114 is a single-color image, horizontal low-pass filter processing is performed. In the image display device according to the second embodiment, the low-pass filter processing in the horizontal direction is performed even when the image displayed on the LCD 114 is an image other than a monochrome image.

  FIG. 9 is a flowchart showing details of the LCD display process performed by the image display apparatus according to the second embodiment. Steps for performing the same processing as the processing in the flowchart shown in FIG. 7 are assigned the same reference numerals, and detailed descriptions thereof are omitted.

If it is determined in step S820 that the display target image is a single color image, the process proceeds to step S910. In step S910, the filter coefficient A used when performing horizontal low-pass filter processing is set. The filter coefficient A is a filter coefficient for performing horizontal low-pass filter processing on single-color image data. For example, in the case of 5 taps, the filter coefficient A is expressed as (1) below. This filter coefficient is stored in the flash memory 117 in advance.
Filter coefficient A: 9/128, 32/128, 46/128, 32/128, 9/128 (1)

If it is determined in step S820 that the image to be displayed is not a single color image, the process proceeds to step S920. In step S920, a filter coefficient B used when performing horizontal low-pass filter processing is set. The filter coefficient B is a filter coefficient for performing the horizontal low-pass filter processing on the non-monochromatic image data. For example, in the case of 5 taps, the filter coefficient B is expressed by the following (2). This filter coefficient is stored in the flash memory 117 in advance.
Filter coefficient B: -9/128, 14/128, 118/128, 14/128, -9/128 (2)

  In step S930, the display image processing unit 120 performs horizontal low-pass filter processing on the display target image. At this time, the filter coefficient A is used when the process of step S910 is performed, and the filter coefficient B is used when the process of step S920 is performed. As can be seen by comparing the filter coefficient A and the filter coefficient B, the non-monochromatic image data is subjected to a low-pass filter process that is weaker than the low-pass filter process applied to the monochromatic image data. That is, low-pass filter processing is also performed on non-monochromatic image data, but the difference in luminance value between adjacent pixels is not as small as when low-pass filter processing is performed on single-color image data.

  As described above, according to the image display device in the second embodiment, the first high-frequency reduction process is performed on single-color image data, and the first high-frequency reduction process is different on non-monochromatic image data. 2 is performed. Thereby, it is possible to suppress the occurrence of false colors not only for single-color image data but also for non-monochromatic image data.

  Here, since the first high-frequency reduction process has a higher high-frequency component reduction effect than the second high-frequency reduction process, it is possible to effectively suppress the occurrence of false colors for monochromatic image data. For monochrome image data, it is possible to suppress the occurrence of false colors while suppressing a decrease in display image quality.

<Third Embodiment>
In the image display device according to the third embodiment, when the image displayed on the LCD 114 is a single-color image, horizontal averaging processing is performed to determine the average values of R, G, and B of the three pixels in the horizontal direction.

  FIG. 10 is a flowchart showing details of the LCD display process performed by the image display apparatus according to the third embodiment. Steps for performing the same processing as the processing in the flowchart shown in FIG. 7 are assigned the same reference numerals, and detailed descriptions thereof are omitted.

  If it is determined in step S820 that the display target image is a single color image, the process advances to step S1010. In step S1010, horizontal averaging processing is performed on monochromatic image data to determine the average values of R, G, and B for the three pixels in the horizontal direction.

  FIG. 11 is a diagram for explaining a process of displaying on the LCD 114 after performing the averaging process of three pixels in the horizontal direction on the monochromatic image data. In FIG. 11, only the six pixels 1110 to 1160 in the horizontal direction are shown as the monochrome image data 1170 before the horizontal averaging process.

The single-color image data 1170 is subjected to the averaging process for three adjacent pixels in the horizontal direction to obtain image data 1180 after the horizontal averaging process. For example, the R, G, and B data of RGB data of adjacent three horizontal pixels 1110, 1120, and 1130 are (R1, G1, B1), (R2, G2, B2), and (R3, G3, B3), respectively. Average values Ra, Ga, and Ba are obtained from the following equations (3), (4), and (5), respectively.
Ra = (R1 + R2 + R3) / 3 (3)
Ga = (G1 + G2 + G3) / 3 (4)
Ba = (B1 + B2 + B3) / 3 (5)

  Therefore, the RGB data of the pixels 1110, 1120, and 1130 after the horizontal averaging process are (Ra, Ga, Ba), respectively. Similarly, the RGB data (Rb, Rg, Rb) after the horizontal averaging process is obtained by performing the averaging process on the adjacent three pixels 1140, 1150, 1160 in the horizontal direction. When the image data 1180 after the horizontal averaging process is displayed on the LCD 114 by the method shown in FIG. 8, the data 1190 of each pixel of the LCD 114 is as shown in FIG.

  Here, the ratio of the luminance values of RGB data Ra, Ga, Ba obtained by the horizontal averaging process of three pixels is equal to the ratio of the luminance values of Rb, Gb, Bb. In FIG. 11, the data 1190 of each pixel of the LCD 114 is shown for only six pixels, but the same applies to other pixels. Therefore, the ratio of the luminance values of the adjacent three pixels corresponding to the R filter, G filter, and B filter among the pixels constituting the LCD 114 is the same, so that the generation of false colors can be effectively suppressed. In addition, it is possible to suppress a decrease in the resolution of the image as compared with the case where the horizontal low-pass filter process is performed.

  As described above, according to the image display device in the third embodiment, when monochromatic image data is displayed on the LCD 114, the luminance value of the target pixel of the LCD 114 and the luminance of one or more adjacent pixels having different target pixels and color filters. High frequency reduction processing is performed so that the ratio of values is the same. Thereby, generation | occurrence | production of a false color can be suppressed more effectively. Here, since the averaging process in the horizontal direction is performed as the high frequency reduction process, the luminance value of the target pixel of the LCD 114 and the luminance value of one or more adjacent pixels different from the target pixel and the color filter are surely made the same. Can do.

<Fourth Embodiment>
In the image display device according to the fourth embodiment, when the image displayed on the LCD 114 is a single-color image, after performing the process of reducing the size so that the size becomes one third in the horizontal direction, the nearest neighbor interpolation method is performed. The process of enlarging 3 times in the horizontal direction is performed.

  FIG. 12 is a flowchart illustrating details of the LCD display process performed by the image display apparatus according to the fourth embodiment. Steps for performing the same processing as the processing in the flowchart shown in FIG. 7 are assigned the same reference numerals, and detailed descriptions thereof are omitted.

  If it is determined in step S820 that the display target image is a single color image, the process advances to step S1200. In step S1200, the monochromatic image data is reduced to a size of one third in the horizontal direction.

  In step S1210, the single-color image data reduced to one third in the horizontal direction is subjected to a process of enlarging it three times in the horizontal direction by the nearest neighbor interpolation method.

  In FIG. 13, after processing to reduce the size of monochromatic image data to one third of the size in the horizontal direction, the processing to enlarge it by three times in the horizontal direction by the nearest neighbor interpolation method is performed. It is a figure for demonstrating the process displayed on LCD114 later.

  The monochromatic image data 1370 is subjected to a process of reducing the size so that the size becomes one third in the horizontal direction, thereby obtaining image data 1380 after the reduction process. In the example shown in FIG. 13, one pixel out of three pixels adjacent in the horizontal direction is extracted to reduce the size to one third of the size in the horizontal direction. The average may be reduced.

  Subsequently, image data 1390 is generated by performing a process of enlarging the reduced image data 1380 three times in the horizontal direction by the nearest neighbor interpolation method. In the nearest neighbor interpolation method, since interpolation is performed using the pixel values of the nearest pixels, the RGB data of the three pixels adjacent in the horizontal direction are equal as shown in FIG. That is, the R data, G data, and B data of the three pixels 1310, 1320, and 1330 are equal, and the R data, G data, and B data of the three pixels 1340, 1350, and 1360 are equal.

  Thereafter, when the image data 1190 enlarged three times in the horizontal direction is displayed on the LCD 114 by the method shown in FIG. 8, the data 1400 of each pixel of the LCD 114 becomes as shown in FIG.

  As a result, the luminance values of the adjacent three pixels corresponding to the R filter, the G filter, and the B filter among the pixels constituting the LCD 114 are the same, so that the generation of false colors can be effectively suppressed. In addition, it is possible to suppress a decrease in the resolution of the image as compared with the case where the horizontal low-pass filter process is performed.

  As described above, according to the image display device of the fourth embodiment, after reducing the monochrome image data to 1/3 times in the horizontal direction, the reduced monochrome image data is multiplied by 3 times in the horizontal direction by the nearest neighbor interpolation method. Perform the process of enlarging. Thereby, since the luminance values of the three pixels adjacent in the horizontal direction can be made the same, the occurrence of false colors can be more effectively suppressed.

  In the description of the first to fourth embodiments described above, hardware processing is assumed as processing performed by the image display device, but the present invention is not limited to such a configuration. For example, a configuration in which processing is performed separately by software is also possible. In this case, the image display device includes a main storage device such as a CPU and a RAM, and a computer-readable storage medium storing a program for realizing all or part of the above processing. Here, this program is called an image display program. Then, the CPU reads out the image display program stored in the storage medium and executes information processing / calculation processing, thereby realizing processing similar to that of the above-described image display device.

  Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, and the like. Alternatively, the image display program may be distributed to a computer via a communication line, and the computer that has received the distribution may execute the image display program.

  The present invention is not limited to the first to fourth embodiments described above, and various modifications and applications can be made without departing from the scope of the present invention. For example, in the third embodiment, since the display image data is composed of RGB data, the averaging process of three pixels in the horizontal direction is performed. However, when the display image data is composed of data of two colors or four colors or more, the averaging process may be performed on the same number of pixels as the number of constituent colors.

  In the fourth embodiment, when the display image data is composed of N (N is a natural number) color data, the monochromatic image data is reduced to 1 / N times in the horizontal direction, and then the reduced image data is displayed. The monochromatic image data may be enlarged N times in the horizontal direction by the nearest neighbor interpolation method.

  As described with reference to FIG. 8, display processing in which each pixel in the horizontal direction of the display image data is associated with each pixel in the horizontal direction of the LCD 114 serving as a display unit is performed. The description has been given assuming that horizontal low-pass filter processing, averaging processing, and reduction / enlargement processing are performed. However, in the case of a display process in which each pixel in the vertical direction of the display unit is associated with each pixel in the vertical direction of the display image data, the low-pass filter process in the vertical direction, the averaging process, the reduction / enlargement What is necessary is just to make it process.

  In the above-described embodiment, description has been made on the assumption that data corresponding to the color filter of each pixel of the LCD 114 is extracted from the image data composed of RGB data and displayed. However, for example, the present invention can also be applied to a display system that performs display on the LCD 114 by performing color conversion on image data composed of YCbCr data.

  In the above-described embodiment, an example in which the image display device is applied to a digital still camera has been described. However, the image display device can also be applied to a digital video camera and other electronic devices.

DESCRIPTION OF SYMBOLS 1 ... Camera body 2 ... Interchangeable lens 101 ... Mechanical shutter 102 ... Imaging element 103 ... Analog processing part 104 ... Analog / digital conversion part 107 ... Image processing part 110 ... Image compression expansion part 113 ... LCD driver 114 ... LCD
115 ... Microcomputer 117 ... Flash memory 118 ... Noise pattern generator 119 ... Image adder 120 ... Display image processor

Claims (12)

A determination unit that determines whether the image data to be displayed is single-color image data;
A high frequency reduction processing unit that performs high frequency reduction processing to reduce high frequency components on the image data;
When the determination unit determines that the image data to be displayed is single-color image data, a control unit that controls the high-frequency reduction processing unit so that the high-frequency reduction processing is performed on the single-color image data;
A display unit for displaying the monochromatic image data subjected to the high-frequency reduction processing;
An image display device comprising:   When the determination unit determines that the image data to be displayed is non-monochromatic image data, the control unit performs the high frequency reduction so that the high frequency reduction processing is not performed on the non-monochromatic image data. The image display device according to claim 1, wherein the processing unit is controlled.   The control unit causes the first high-frequency reduction process to be performed on the monochrome image data, and the second high-frequency reduction process different from the first high-frequency reduction process is performed on the non-monochromatic image data. The image display apparatus according to claim 1, wherein the high-frequency reduction processing unit is controlled as described above.   The image display apparatus according to claim 3, wherein the first high-frequency reduction process is a process that has a higher high-frequency component reduction effect than the second high-frequency reduction process.   5. The image display device according to claim 1, wherein the high-frequency reduction processing unit performs horizontal low-pass filter processing as high-frequency reduction processing for the monochromatic image data. 6.   When the high-frequency reduction processing unit displays the monochrome image data on the display unit, the luminance value of the target pixel of the display unit and the luminance value of one or more adjacent pixels different from the target pixel and the color filter are obtained. 5. The image display device according to claim 1, wherein high-frequency reduction processing is performed on the monochromatic image data so that the ratios are the same. 6.   The image display apparatus according to claim 6, wherein the high frequency reduction processing unit performs horizontal averaging processing as the high frequency reduction processing for the monochrome image data.   The high-frequency reduction processing unit performs a process of reducing the monochrome image data and a process of expanding the reduced monochrome image data as the high-frequency reduction process for the monochrome image data. Item 5. The image display device according to any one of Items 4 to 6.   The high-frequency reduction processing unit reduces the monochrome image data to 1 / N (N is a natural number) times in the horizontal direction, and then enlarges the reduced monochrome image data to N times in the horizontal direction by a nearest neighbor interpolation method. The image display device according to claim 8, wherein the image display device performs the processing.   The image display device according to any one of claims 1 to 9, wherein the display unit displays a part of data of data of each pixel constituting the image data.   The image display apparatus according to claim 1, wherein the monochrome image data is monochrome image data to which noise data is added. An image display method for displaying image data on a display unit,
Determining whether the image data to be displayed is single-color image data;
If it is determined that the image data to be displayed is single-color image data, performing a high-frequency reduction process for reducing high-frequency components on the single-color image data;
Displaying monochromatic image data subjected to the high-frequency reduction processing;
An image display method comprising: