JP2005167465A - Digital camera and imaging method of digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera capable of preventing the occurrence of the saturation of colors in an object image and to provide an imaging method of the digital camera. <P>SOLUTION: A microcomputer 40 detects a high saturation region wherein the saturation of colors of the object image denoted by color image information acquired by a CCD 24 is higher than a prescribed degree and adjusts a luminous quantity made incident into a light receiving region of the CCD 24 by partially adjusting the transmissivity of an LCD 23 so that the quantity of light made incident into the region corresponding to the high saturation region in the light receiving region by the CCD 24 is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital camera and an imaging method of the digital camera, and more particularly, to a digital camera including an imaging unit that can acquire image information indicating a subject image in color and an imaging method of the digital camera.

  In recent years, the demand for digital cameras such as digital electronic still cameras and digital video cameras has been increasing rapidly with the increase in resolution of imaging devices such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) image sensors. In this type of digital camera, when color reproducibility is important, a CCD using primary color filters of R (red), G (green), and B (blue) is generally used.

  By the way, the CCD has a narrow dynamic range compared to a photographic film using silver salt. Therefore, when a high-luminance object such as a luminaire or the sun exists in the shooting screen, the high-luminance area and other areas The brightness difference becomes large and proper exposure cannot be set. This is because the CCD output signal in the high brightness area is saturated when the exposure is set according to the area other than the high brightness area, and conversely, when the exposure is set according to the high brightness area, This is because the area becomes dark.

In order to solve this problem, Patent Document 1 includes a light-receiving unit for photometry and a light-reducing unit that limits the amount of light incident on the light-receiving unit. A technique for controlling the dimming means so as to limit the amount of light incident on a certain region is disclosed.
Japanese Patent Laid-Open No. 7-120309

  By the way, even when a high density subject is photographed with a digital camera, a similar phenomenon may occur with respect to color. For example, when a bright red rose is photographed, the red color of the CCD output signal may be saturated depending on the balance of the spectral characteristics of R, G, B when the saturation of the flower color is very high. There was a problem that countermeasures could not be taken by signal processing.

  Further, in the technique according to Patent Document 1, although the exposure can be set appropriately, no consideration is given to the color density of the subject, and the occurrence of color saturation in the subject image cannot be prevented. There was a problem.

  The present invention has been made to solve the above problems, and an object thereof is to provide a digital camera and an imaging method for the digital camera that can prevent color saturation in a subject image.

  In order to achieve the above object, a digital camera according to claim 1 is an image capturing unit that receives light from a subject and acquires color image information indicating a subject image, and partially transmits light from the subject. A light amount adjusting unit that adjusts the amount of light incident on the light receiving region of the image pickup unit, and a detection that detects a high saturation region in which the color saturation of the subject image indicated by the color image information is higher than a predetermined degree And a control means for controlling the light amount adjusting means so as to reduce the amount of light incident on the region corresponding to the high saturation region detected by the detecting means, among the light receiving areas by the imaging means. Yes.

  According to the digital camera of the first aspect, the light from the subject is received by the imaging unit, and the color image information indicating the subject image is acquired. Note that the imaging means includes a solid-state imaging device such as a CCD or a CMOS image sensor.

  Here, the digital camera of the present invention is provided with a light amount adjusting means for adjusting the light amount incident on the light receiving area of the imaging means by partially changing the transmittance of light from the subject. In the invention, a high saturation region in which the saturation of the color of the subject image indicated by the color image information is higher than a predetermined degree is detected by the detection unit, and among the light receiving regions by the imaging unit, the high level detected by the detection unit is detected. The light quantity adjusting means is controlled by the control means so that the light quantity incident on the area corresponding to the saturation degree area is reduced.

  As described above, according to the digital camera of claim 1, a high saturation region in which the saturation of the color of the subject image indicated by the color image information acquired by the imaging unit is higher than a predetermined degree is detected, and the imaging is performed. The amount of light incident on the light receiving area of the imaging means is adjusted so as to reduce the amount of light incident on the area corresponding to the high saturation area in the light receiving area by the means, and therefore, signal processing for color image information is involved. Without saturation, that is, without increasing the circuit scale, it is possible to prevent color saturation in the subject image.

  By the way, the color image information acquired by the imaging means is normally acquired as indicating the density level for each of R, G, and B primary colors.

  Therefore, as in the invention described in claim 2, the detection means of the present invention uses, as the high saturation region, a region where at least one of the density levels for each primary color indicated by the color image information is higher than a predetermined level. It is preferable to detect. As a result, the high saturation region of the present invention can be easily detected without requiring complicated calculations.

  Further, as in the invention according to claim 3, the light amount adjusting means of the present invention has the same arrangement and the same number of pixels as the pixels constituting the subject image indicated by the color image information acquired by the imaging means. It is preferable to use a liquid crystal display having This makes it possible to adjust the amount of light incident on the light receiving area of the imaging means for each pixel of the subject image, and to adjust the amount of light intensity in units of pixels in the boundary area between the high saturation area and other areas. Since switching is possible, it is possible to avoid the occurrence of a situation in which the brightness of the subject image changes at an unnatural position.

  Furthermore, as in the invention described in claim 4, the present invention further includes a color adjusting unit that adjusts a hue by adjusting a density level for each primary color with respect to the color image information acquired by the imaging unit. The control means further controls the color adjustment means so as to adjust pixel information of an area corresponding to the high saturation area in the color image information in accordance with an adjustment amount of the light quantity by the light quantity adjustment means. It is preferable to do.

  That is, the digital camera is generally provided with a color adjusting unit according to the present invention in order to cope with a user's preference for color tone. Therefore, in the present invention, the color image information is adjusted according to the adjustment amount of the incident light quantity with respect to the imaging means by using the color adjustment means, and a new means for adjusting the color image information is provided. Therefore, the color image information can be adjusted easily and at a low cost.

  On the other hand, in order to achieve the above object, an imaging method of a digital camera according to claim 5 is an imaging method of a digital camera provided with imaging means for receiving light from a subject and acquiring color image information indicating a subject image. And detecting a high saturation region where the saturation of the color of the subject image indicated by the color image information is higher than a predetermined degree, and in a region corresponding to the high saturation region among the light receiving regions by the imaging means. The amount of light incident on the light receiving area of the imaging means is adjusted so that the amount of incident light is reduced.

  Therefore, according to the fifth aspect of the invention, the digital camera can be operated in the same manner as the first aspect of the invention, so that the signal for the color image information is the same as the first aspect of the invention. The generation of color saturation in the subject image can be prevented without processing, that is, without increasing the circuit scale.

  According to the digital camera and the imaging method of the digital camera according to the present invention, a high saturation region in which the saturation of the color of the subject image indicated by the color image information acquired by the imaging unit is higher than a predetermined degree is detected, and the imaging is performed. The amount of light incident on the light receiving area of the imaging means is adjusted so as to reduce the amount of light incident on the area corresponding to the high saturation area in the light receiving area by the means, and therefore, signal processing for color image information is involved. In other words, it is possible to prevent the occurrence of color saturation in the subject image without increasing the circuit scale.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

[First Embodiment]
First, an external configuration of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  In front of the digital camera 10, a lens 21 for forming a subject image, a strobe 44 that emits light to irradiate the subject when necessary, and a viewfinder used to determine the composition of the subject to be photographed. 20 is provided. Further, on the upper surface of the digital camera 10, a release button (so-called shutter) 56A that is pressed when performing shooting and a power switch 56B are provided.

  Note that the release button 56A of the digital camera 10 according to the present embodiment is pressed down to an intermediate position (hereinafter referred to as “half-pressed state”) and to a final pressed position beyond the intermediate position. A two-stage pressing operation of a state (hereinafter referred to as a “fully pressed state”) can be detected.

  In the digital camera 10, the release button 56A is pressed halfway to activate the AE (Automatic Exposure) function to set the exposure state (shutter speed, aperture state), and then AF (Auto Focus). , Automatic focusing) function is performed to control focusing, and then exposure (photographing) is performed when the button is fully pressed.

  On the other hand, on the back surface of the digital camera 10, an eyepiece of the finder 20 described above and a liquid crystal display (hereinafter referred to as “LCD”) 38 for displaying a photographed subject image, a menu screen, and the like are provided. It has been.

  Also, on the back of the digital camera 10, a mode changeover switch 56C that is slid to be set to any one of a photographing mode that is a photographing mode and a reproduction mode that is a mode for reproducing a subject image by the LCD 38, Further, a cross cursor button 56D and a forced light emission switch 56E that is pressed when setting the forced light emission mode, which is a mode for forcibly causing the flash 44 to emit light at the time of shooting, are further provided.

  The cross-cursor button 56D includes four arrow keys that indicate four moving directions of up, down, left, and right in the display area of the LCD 38.

  Next, the configuration of the electrical system of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  The digital camera 10 receives an optical unit 22 including the lens 21 described above, an LCD 23 and a charge coupled device (hereinafter referred to as “CCD”) 24 disposed behind the optical axis of the lens 21. And an analog signal processing unit 26 that performs various analog signal processing on the analog signal.

  The LCD 23 is for adjusting the amount of light incident on the light receiving area of the CCD 24 by partially changing the transmittance of the light flux from the subject, and is located in the vicinity of the CCD 24 between the optical unit 22 and the CCD 24. Has been placed.

  The CCD 24 is provided with color filters of R, G, and B in accordance with a predetermined arrangement on the light receiving surface of each light receiving element. Here, examples of the predetermined arrangement include the Bayer arrangement shown in FIG. 3A, the G stripe R / B complete checkered arrangement shown in FIG. 3B, and the honeycomb arrangement shown in FIG. it can.

  In each of these color filter arrays, the number of G color filters is doubled with respect to R and B, and even if any color filter array is applied, the CCD 24 , R and B analog signals are output in time series and intermittently. Therefore, in any color filter array, signal processing (so-called synchronization processing) is performed by interpolating and generating intermittent R and B analog signals with analog signals of peripheral pixels.

  In any color filter array, one pixel in the subject image is represented by analog signals obtained by the four light receiving element groups adjacent to each other in the CCD 24. In the present embodiment, a CCD having color filters arranged in a Bayer array is used as the CCD 24.

  On the other hand, the LCD 23 has the same arrangement and the same number of pixels (hereinafter referred to as “liquid crystal pixels”) as the respective pixels constituting the subject image indicated by the analog signal output from the CCD 24. The arrangement position of the LCD 23 is adjusted so that the pixels correspond to the four light receiving element groups in the CCD 24 on a one-to-one basis.

  The LCD 23 according to the present embodiment is of a TFT (Thin Film Transistor) type, and a light beam transmitted through each liquid crystal pixel is incident on a light receiving element group corresponding to each liquid crystal pixel.

  Here, each liquid crystal pixel is configured to be able to apply a different voltage, whereby the light flux transmittance can be changed for each liquid crystal pixel.

  That is, as an operation method of the LCD, a twisted nematic method (hereinafter referred to as “TN method”) using the optical rotation of the liquid crystal, or a guest / host method in which a dichroic dye is mixed and aligned in the liquid crystal ( Hereinafter, it is referred to as “GS method”). The relationship between the voltage applied to the liquid crystal and the transmittance of the liquid crystal in the TN mode and the GS mode is as shown in FIGS. 4A and 4B as an example. As shown in the figure, in any method, the transmittance of the liquid crystal can be changed by changing the voltage applied to the liquid crystal. Note that the TN method has a larger change width of the light transmittance than the GS method, and a high contrast can be obtained. For this reason, in the present embodiment, a TN type LCD is adopted as the LCD 23.

  On the other hand, as shown in FIG. 2, the digital camera 10 includes an analog / digital converter (hereinafter referred to as “ADC”) 28 that converts an input analog signal into digital data, and an input digital data. And a digital signal processing unit 30 that performs various types of digital signal processing.

  The digital signal processing unit 30 has a built-in line buffer having a predetermined capacity, and also performs control to directly store the input digital data in a predetermined area of the memory 48 described later.

  The output terminal of the CCD 24 is connected to the input terminal of the analog signal processing unit 26, the output terminal of the analog signal processing unit 26 is connected to the input terminal of the ADC 28, and the output terminal of the ADC 28 is connected to the input terminal of the digital signal processing unit 30. . Accordingly, the analog signal indicating the subject image output from the CCD 24 is subjected to predetermined analog signal processing by the analog signal processing unit 26, converted into digital image data by the ADC 28, and then input to the digital signal processing unit 30.

  On the other hand, the digital camera 10 includes a microcomputer 40 that controls the operation of the entire digital camera 10 and a memory 48 that stores digital image data and the like obtained by photographing. The microcomputer 40 stores in advance a voltage-to-transmittance table (see FIG. 4A as an example) that shows the relationship between the voltage applied to each liquid crystal pixel in the CCD 24 and the transmittance, and various programs. A nonvolatile memory 40A is incorporated.

  Further, the digital camera 10 is configured such that a portable recording medium 52 is detachable, and the recording medium 52 can be accessed by the digital signal processing unit 30 with the recording medium 52 mounted.

  In the digital camera 10 according to the present embodiment, a VRAM (Video RAM) is used as the memory 48 and a smart media (Smart Media®) is used as the recording medium 52.

  Further, the digital camera 10 includes a compression / decompression processing unit 54 that performs compression processing and decompression processing on digital image data.

  Further, the digital camera 10 is provided with a digital / analog converter (hereinafter referred to as “DAC”) 60 that converts input digital data into an analog signal, and cooperates with the digital signal processing unit 30. A video signal indicating an image to be displayed on the LCD 38 (in this embodiment, an NTSC signal) can be generated and output as a video output from a video output terminal (not shown).

  On the other hand, the digital camera 10 includes a timing generator 32 that mainly generates a timing signal for driving the CCD 24 and supplies the timing signal to the CCD 24, and the driving of the CCD 24 is controlled by the microcomputer 40 via the timing generator 32. The

  The microcomputer 40 is connected to the input end of the motor drive unit 62, and the output end of the motor drive unit 62 is connected to the focus adjustment motor, zoom motor, and aperture drive motor provided in the optical unit 22.

  The lens 21 according to the present embodiment has a plurality of lenses, is configured as a zoom lens that can change (magnify) the focal length, and includes a lens driving mechanism (not shown). The lens drive mechanism includes the focus adjustment motor, the zoom motor, and the aperture drive motor. The focus adjustment motor, the zoom motor, and the aperture drive motor are supplied from the motor drive unit 62 under the control of the microcomputer 40, respectively. Driven by a drive signal.

  When changing the optical zoom magnification, the microcomputer 40 controls the zoom motor to change the focal length of the lens 21 included in the optical unit 22.

  Further, the microcomputer 40 performs focus control by driving and controlling the focus adjustment motor so that the contrast of an image obtained by imaging by the CCD 24 is maximized. In other words, the digital camera 10 according to the present embodiment employs a so-called TTL (Through The Lens) method in which the lens position is set so that the contrast of the read image is maximized as the focus control. .

  The microcomputer 40 is also connected to the LCD 23 and the strobe 44, and can change the transmittance of each liquid crystal pixel in the LCD 23 for each liquid crystal pixel and can control the light emission of the strobe 44.

  Further, the release button 56A, the power switch 56B, the mode changeover switch 56C, the cross cursor button 56D, and the forced light emission switch 56E (generically referred to as “operation unit 56” in the figure) are connected to the microcomputer 40. The microcomputer 40 can always grasp the operation state of the operation unit 56.

  Next, the overall operation of the digital camera 10 according to the present embodiment in the shooting mode will be briefly described.

  First, a subject image is picked up by the CCD 24, and analog signals for R, G, and B indicating the subject image are sequentially output to the analog signal processing unit 26. The analog signal processing unit 26 performs analog signal processing such as correlated double sampling processing on the analog signal input from the CCD 24 and sequentially outputs the analog signal to the ADC 28.

  The ADC 28 converts the R, G, and B analog signals input from the analog signal processing unit 26 into 12-bit R, G, and B signals (digital image data) and sequentially outputs them to the digital signal processing unit 30. To do. The digital signal processing unit 30 accumulates digital image data sequentially input from the ADC 28 in a built-in line buffer and temporarily stores the digital image data directly in a predetermined area of the memory 48.

  Digital image data stored in a predetermined area of the memory 48 is read out by the digital signal processing unit 30 in accordance with control by the microcomputer 40, and a digital gain corresponding to a predetermined physical quantity is applied to each of R, G, and B. The white balance is adjusted by adjusting the color tone by applying a digital gain preset for each pixel for each of R, G, and B (hereinafter referred to as “color adjustment processing”) and sharpness processing is performed. To generate 8-bit digital image data.

  Then, the digital signal processing unit 30 performs YC signal processing on the generated 8-bit digital image data to perform luminance signal Y and color difference signals Cr (= R−Y), Cb (= B−Y) (hereinafter, “ YC signal ") is generated, and the YC signal is stored in an area different from the predetermined area of the memory 48.

  The LCD 38 is configured to display a moving image (through image) obtained by continuous imaging by the CCD 24 and can be used as a finder. When the LCD 38 is used as a finder, the LCD 38 is generated. The YC signals thus obtained are sequentially supplied to the LCD 38 as image signals. As a result, a through image is displayed on the LCD 38.

  Here, when the release button 56A is half-pressed by the user, after the AE function is activated and the exposure state is set as described above, the AF function is activated and focus control is performed, and then the fully-pressed state is continued. In this case, the YC signal stored in the memory 48 at this time is compressed in a predetermined compression format (in this embodiment, JPEG format) by the compression / expansion processing unit 54 and then recorded on the recording medium 52. .

  By the way, in the digital camera 10, when the image is captured by the CCD 24, color saturation adjustment is performed so that the amount of light flux incident on the light receiving region of the CCD 24 corresponding to the high saturation region where the color saturation of the subject image is high is reduced. Processing is executed. Hereinafter, the color saturation adjustment process will be described with reference to FIG. FIG. 5 is a flowchart showing a processing flow of a color saturation adjustment processing program executed in the microcomputer 40 every predetermined period (0.1 seconds in the present embodiment) during imaging by the CCD 24. The program is stored in advance in the memory 40A.

  In step 100 of the figure, from the 8-bit R, G, B digital image data generated at this time, a subject image indicated by the digital image data is divided into a predetermined number of divided areas in the vertical and horizontal directions, respectively. (In the present embodiment, all the areas corresponding to one divided area (hereinafter referred to as “process target area”) when divided into 100 divided in total in the vertical direction and the horizontal direction are divided into 100 divided areas). Pixel data is acquired from the digital signal processing unit 30, and an integrated value of the pixel data for each of R, G, and B is calculated.

  In the next step 102, it is determined whether or not there is a calculated integrated value for each of R, G, and B that exceeds a predetermined first threshold value. It is determined that there is a high possibility that color saturation will occur, and the routine proceeds to step 104.

  In the present embodiment, as the first threshold, a value obtained by multiplying the maximum value (255 in the present embodiment) that can be taken by the pixel data by the number of pixels included in the processing target region. A value obtained by multiplying (the maximum value that each integrated value can take) by a predetermined value (0.9 in this embodiment) is applied. That is, in the present embodiment, a value that is 90% of the maximum value that each integrated value can take is applied as the first threshold value.

  In step 104, the transmittance of the liquid crystal pixels of the LCD 23 corresponding to the processing target area is calculated according to the magnitude of the integrated value exceeding the first threshold. In the present embodiment, when there is one integrated value that exceeds the first threshold, the transmittance is calculated such that the transmittance decreases as the integrated value increases, and exceeds the first threshold. When there are a plurality of integrated values, the transmittance is calculated to be lower as the maximum integrated value increases.

  In the next step 106, an applied voltage corresponding to the transmittance calculated in step 104 is specified by referring to the voltage vs. transmittance table stored in the memory 40A, and the applied voltage corresponds to the processing target region. An LCD control signal for applying to the liquid crystal pixel is output to the LCD 23. As a result, the light incident on the light receiving area of the CCD 24 corresponding to the processing target area is dimmed according to the transmittance calculated in step 104, and color saturation in the processing target area can be prevented.

  In the next step 108, the digital gain used for the region corresponding to the processing target region is adjusted in the color adjustment processing performed in the digital signal processing unit 30 according to the transmittance calculated in step 104, and then The process proceeds to step 116. By the processing in step 108, it is possible to cope with a reduction in the value of the digital image data in accordance with the light attenuation by the LCD 23.

  In the present embodiment, the digital gain is the reciprocal of the transmittance (for example, if the transmittance is 80% with respect to the digital gain set in accordance with the user's preference etc. at this time). 25 (= 1 / 0.8)).

  On the other hand, if a negative determination is made in step 102, that is, if there is no integrated value for each of R, G, and B calculated in step 100 that exceeds the first threshold, the process proceeds to step 110. Then, it is determined whether or not all the integrated values for each of R, G, and B are equal to or less than a predetermined second threshold value. If the determination is affirmative, the process proceeds to step 112.

  In the present embodiment, as the second threshold value, a value obtained by multiplying the maximum value (255 in the present embodiment) that can be taken by the pixel data by the number of pixels included in the processing target area. A predetermined value (0.1 in the present embodiment) smaller than the predetermined value (0.9 in the present embodiment) applied to the calculation of the first threshold value is set as (the maximum value that each integrated value can take). The value obtained by multiplication is applied. That is, in this embodiment, a value that is 10% of the maximum value that each integrated value can take is applied as the second threshold value.

  In step 112, the LCD control signal for turning off the liquid crystal pixels corresponding to the processing target area of the LCD 23, that is, the total transmission (transmittance 100%) is output to the LCD 23. Thereby, the light attenuation when the light incident on the light receiving area of the CCD 24 corresponding to the processing target area is attenuated by the LCD 23 is canceled, and the dynamic range of the light receiving area of the CCD 24 corresponding to the processing target area is canceled. Unnecessary reduction can be canceled.

  In the next step 114, the digital gain used for the region corresponding to the processing target region is returned to the preset one in the color adjustment processing performed in the digital signal processing unit 30, and then the process proceeds to step 116. To do.

  On the other hand, if a negative determination is made in step 110, that is, if all integrated values for R, G, and B calculated in step 100 are not less than or equal to a predetermined second threshold value, steps 112 and The process proceeds to step 116 without executing the process of step 114.

  In step 116, it is determined whether or not the processing in steps 100 to 114 has been completed for all the divided regions assumed in step 100 (10000 divided regions in the present embodiment), and a negative determination is made. Returns to step 100, and when the determination is affirmative, the color saturation adjustment processing program is terminated. Note that when executing the repetitive processing of Step 100 to Step 116, the microcomputer 40 applies the divided areas that have not been processed as the processing target areas so far.

  As described above in detail, in the present embodiment, a high saturation area where the saturation of the color of the subject image indicated by the color image information acquired by the CCD 24 is higher than a predetermined degree is detected, and the light receiving area of the CCD 24 is detected. Of these, the amount of light incident on the light receiving region of the CCD 24 is adjusted so that the amount of light incident on the region corresponding to the high saturation region is reduced. The occurrence of color saturation in the subject image can be prevented without causing an increase.

  In the present embodiment, since the region where at least one of the density levels for each primary color indicated by the color image information is higher than a predetermined level is detected as the high saturation region, the high saturation region is It is possible to easily detect without requiring complicated calculation.

  Further, in the present embodiment, a digital signal processing unit 30 that adjusts the hue by adjusting the density level for each primary color with respect to the color image information acquired by the CCD 24 is provided, and the amount of light adjustment by the LCD 23 is adjusted. Accordingly, since the digital signal processing unit 30 is controlled so as to adjust the pixel information of the region corresponding to the high saturation region in the color image information, the digital signal processing unit 30 generally provided in a digital camera is used. The color image information can be adjusted according to the amount of adjustment of the incident light quantity with respect to the CCD 24, and the color image information can be easily and inexpensively provided without newly providing means for adjusting the color image information. Adjustments can be made.

  In the present embodiment, the case where an LCD having the same array and the same number of pixels as the subject image pixels is applied as the light amount adjusting means of the present invention has been described, but the present invention is not limited to this. For example, a configuration may be adopted in which the same area and the same number of pixels as the divided areas assumed in the processing of step 100 of the color saturation adjustment processing program are applied. In this case, the LCD 23 can be made lower in cost than the present embodiment, and as a result, the cost of the digital camera 10 can be reduced.

[Second Embodiment]
In the first embodiment, the description has been given of the case where the color saturation adjustment is performed for each divided region constituted by a plurality of pixels, but in the second embodiment, the color saturation is performed in units of each pixel. A description will be given of a case where the adjustment is executed. Note that the configuration of the digital camera 10 according to the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted here. In addition, since the overall operation of the digital camera 10 according to the present embodiment in the shooting mode is the same as that of the first embodiment, description thereof is omitted here.

  Hereinafter, the color saturation adjustment processing according to the second embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the processing flow of the color saturation adjustment processing program executed in the microcomputer 40 every predetermined period (0.1 seconds in the present embodiment) at the time of imaging by the CCD 24. The program is stored in advance in the memory 40A.

  In step 200 of the figure, pixel data for one pixel in the subject image is acquired from the digital signal processing unit 30 from the 8-bit R, G, B digital image data generated at this time, and the pixel data Among these, if it is determined whether there is a pixel exceeding a predetermined third threshold and the determination is affirmative, color saturation may occur in the pixel (hereinafter referred to as “processing target pixel”). The process proceeds to step 202 when it is determined that the characteristics are high.

  In the present embodiment, the third threshold value is obtained by multiplying the maximum value (255 in the present embodiment) that can be taken by the pixel data by a predetermined value (0.9 in the present embodiment). The specified value is applied. That is, in this embodiment, 90% of the maximum value that each pixel data can take is applied as the third threshold value.

  In step 202, the transmittance of the liquid crystal pixel of the LCD 23 corresponding to the processing target pixel is calculated according to the size of the pixel data exceeding the third threshold. In the present embodiment, when there is one piece of pixel data that exceeds the third threshold, the transmittance is calculated so that the transmittance decreases as the pixel data increases, and exceeds the third threshold. If there is a plurality of pixel data, the transmittance is calculated to be lower as the maximum pixel data among them becomes larger.

  In the next step 204, an applied voltage corresponding to the transmittance calculated in step 202 is specified by referring to the voltage versus transmittance table stored in the memory 40A, and the applied voltage corresponds to the processing target pixel. An LCD control signal for applying to the liquid crystal pixel is output to the LCD 23. As a result, light incident on the light receiving region of the CCD 24 corresponding to the processing target pixel is attenuated according to the transmittance calculated in step 202, and color saturation in the processing target pixel can be prevented.

  In the next step 206, the digital gain used for the pixel corresponding to the pixel to be processed is adjusted in the color adjustment process performed in the digital signal processing unit 30 according to the transmittance calculated in the above step 202, and then The process proceeds to step 214. By the processing in step 206, it is possible to cope with a reduction in the value of the digital image data corresponding to the light reduction by the LCD 23.

  In the present embodiment, the digital gain is the reciprocal of the transmittance (for example, if the transmittance is 80% with respect to the digital gain set in accordance with the user's preference etc. at this time). 25 (= 1 / 0.8)).

  On the other hand, if the determination in step 200 is negative, that is, if there is no pixel data of the processing target pixel that exceeds the third threshold value, the process proceeds to step 208, and all the pixel data of the processing target pixel is displayed. Is less than or equal to a predetermined fourth threshold value. If the determination is affirmative, the process proceeds to step 210.

  In the present embodiment, as the fourth threshold value, a maximum value (255 in the present embodiment) that the pixel data can take is set to a predetermined value (in the present embodiment) applied to the calculation of the third threshold value. , 0.9), a value obtained by multiplication by a predetermined value (0.1 in this embodiment) is applied. That is, in the present embodiment, a value that is 10% of the maximum value that the pixel data can take is applied as the fourth threshold value.

  In step 210, the LCD control signal for turning off the liquid crystal pixel corresponding to the pixel to be processed of the LCD 23, that is, the total transmission (transmittance 100%) is output to the LCD 23. As a result, the light attenuation when the light incident on the light receiving region of the CCD 24 corresponding to the processing target pixel is attenuated by the LCD 23 is canceled, and the dynamic range in the light receiving region of the CCD 24 corresponding to the processing target pixel is canceled. Unnecessary reduction can be canceled.

  In the next step 212, the digital gain used for the pixel corresponding to the pixel to be processed in the color adjustment process performed in the digital signal processing unit 30 is restored to the preset one, and then the process proceeds to step 214. To do.

  On the other hand, if a negative determination is made in step 208, that is, if all pixel data for each of R, G, and B acquired in step 200 is not less than or equal to a predetermined fourth threshold value, the steps 210 and The process proceeds to step 214 without executing the process of step 212.

  In step 214, it is determined whether or not the processing in steps 200 to 212 has been completed for all the pixels of the subject image. The saturation adjustment processing program is terminated. Note that when executing the repetitive processing of Step 200 to Step 214 described above, the microcomputer 40 applies pixels that have not been processed so far as processing pixels.

  As described above in detail, in the present embodiment, in addition to the effects of the first embodiment, a subject image indicated by the color image information acquired by the CCD 24 is configured as the light amount adjusting means of the present invention. Since an LCD having the same array and the same number of pixels as each pixel is applied and the amount of light incident on the light receiving area of the CCD 24 is adjusted for each pixel of the subject image, the high saturation area and the other areas Since the degree of light amount adjustment can be switched in units of pixels in the boundary region between them, it is possible to avoid a situation in which the brightness of the subject image changes at an unnatural position.

  In each of the above embodiments, the case where the adjustment of the digital image data corresponding to the dimming by the LCD 23 is described by adjusting the digital gain used in the color adjustment processing, but the present invention is limited to this. For example, it may be configured by adjusting a digital gain used in white balance adjustment. Also in this case, the same effects as those of the above embodiments can be obtained.

  Further, the configuration of the digital camera 10 according to each of the above-described embodiments (see FIGS. 1 to 3) is an example, and it is needless to say that the configuration can be appropriately changed without departing from the gist of the present invention.

  Furthermore, the processing flow of the color saturation adjustment processing program (see FIGS. 5 and 6) described in each of the above embodiments is also an example, and can be appropriately changed without departing from the gist of the present invention. Needless to say.

It is an external view which shows the external appearance of the digital camera 10 which concerns on embodiment. 2 is a block diagram showing a configuration of an electric system of the digital camera 10. FIG. It is the schematic which shows the example of an arrangement | sequence of the color filter of R, G, B each color provided on the light-receiving surface of the light receiving element of CCD24 which concerns on embodiment. (A) is a graph showing the relationship between the voltage applied to the liquid crystal in the TN mode and the transmittance of the liquid crystal, and (B) is a graph showing the relationship between the voltage applied to the liquid crystal in the GS mode and the transmittance of the liquid crystal. is there. It is a flowchart which shows the flow of a process of the color saturation adjustment processing program which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the color saturation adjustment processing program which concerns on 2nd Embodiment.

Explanation of symbols

10 Digital camera 23 LCD (light quantity adjustment means)
24 CCD (imaging means)
30 Digital signal processor (color adjustment means)
38 LCD
40 Microcomputer (detection means, control means)

Claims (5)

Imaging means for receiving light from a subject and obtaining color image information indicating a subject image;
A light amount adjusting unit that adjusts a light amount incident on a light receiving region of the imaging unit by partially changing a transmittance of light from the subject;
Detecting means for detecting a high saturation region in which the saturation of the color of the subject image indicated by the color image information is higher than a predetermined degree;
Control means for controlling the light amount adjusting means so as to reduce the amount of light incident on the region corresponding to the high saturation area detected by the detection means among the light receiving areas by the imaging means;
Digital camera equipped with. The digital camera according to claim 1, wherein the detection unit detects, as the high saturation region, a region in which at least one of density levels for each primary color indicated by the color image information is higher than a predetermined level. 3. The digital display according to claim 1, wherein the light amount adjusting unit is a liquid crystal display having the same array and the same number of pixels as each of the pixels constituting the subject image indicated by the color image information acquired by the imaging unit. camera. The color image information acquired by the imaging unit further includes a color adjustment unit that adjusts the hue by adjusting the density level for each primary color, and
The control means further controls the color adjustment means to adjust pixel information of an area corresponding to the high saturation area in the color image information in accordance with an adjustment amount of light quantity by the light quantity adjustment means. The digital camera according to any one of claims 1 to 3. An imaging method for a digital camera comprising imaging means for receiving light from a subject and acquiring color image information indicating a subject image,
Detecting a high saturation region in which the saturation of the color of the subject image indicated by the color image information is higher than a predetermined degree;
An imaging method for a digital camera, wherein the amount of light incident on the light receiving region of the imaging unit is adjusted so that the amount of light incident on the region corresponding to the high saturation region of the light receiving region by the imaging unit is reduced.

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