JP4432040B2 - Shading data generation method - Google Patents

Description

  The present invention relates to a shading data generation method, and more particularly to a shading data generation method for generating shading data for correcting non-uniformity of characteristics of each pixel of a solid-state imaging device.

  A solid-state imaging device used in an electronic camera or the like has different sensitivities for each pixel. Due to the difference in sensitivity, even if uniform light is irradiated, an output difference occurs between the pixels.

  Therefore, shading correction is performed in order to correct the output difference due to the difference in sensitivity between the pixels. This shading correction is performed by correcting the imaging data with predetermined shading data, and the shading data is generated from imaging data obtained by irradiating the solid-state imaging device with uniform light.

Thus, since shading data for performing shading correction is generated by irradiating the solid-state image sensor with uniform light, in Patent Document 1, uniform light is applied to the solid-state image sensor between the solid-state image sensor and the lens. It has been proposed to provide a lighting device for irradiating.
JP 2002-158926 A

  However, the configuration of Patent Document 1 has a drawback in that an imaging device is increased in size and cost because an illumination device must be provided inside the imaging device.

  Further, since shading is also generated by a lens, the method of Patent Document 1 has a drawback that shading generated by the lens cannot be corrected.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a shading data generation method capable of easily generating shading data.

In order to achieve the above object, the invention according to claim 1 is an electronic camera that performs shading correction on image data obtained from a solid-state imaging device using shading data stored in a storage unit. A shading data generation method for generating shading data for storage in a unit, wherein the mode is set to the shading data generation mode, and when the mode is set to the shading data generation mode, the photographing lens is set to a predetermined focal length. And means for causing the strobe light to be emitted from the strobe when the shooting is instructed in the shading data generation mode, and exposing the solid-state imaging device at a predetermined shutter speed and aperture value, and the exposure Generate shading data from image data obtained by Provided with means, and means for storing in the storage unit generated the shading data to the electronic camera, the electronic camera mode to the shading data generation mode, predetermined distance away from the light receiving surface of the solid-state imaging device A shading data generation method is provided , wherein the shading data is generated by photographing a diffusion plate installed at a predetermined position.

  According to the present invention, the solid-state image sensor is irradiated with uniform light using the strobe provided in the photographing apparatus. That is, the strobe light is applied to a diffusion plate installed at a predetermined distance from the light receiving surface of the solid-state image sensor, and the reflected light is irradiated to the solid-state image sensor. Accordingly, it is possible to easily generate shading data without using separate illumination means for generating shading data. In addition, the apparatus configuration can be simplified.

According to a second aspect of the present invention, there is provided an electronic camera that performs shading correction using shading data stored in a storage unit for image data obtained from a solid-state imaging device , in order to achieve the above object. A shading data generation method for generating shading data to be stored in a storage means, wherein a movable monitor, a means for setting a mode to a shading data generation mode, and a mode is set to the shading data generation mode When the photographing lens is set to a predetermined focal length, the monitor emits light at a predetermined luminance and color temperature, and shooting is instructed in the state of the shading data generation mode, a predetermined shutter speed and aperture value are set. And means for exposing the solid-state imaging device, and obtained by the exposure Means for generating shading data from the image data, the generated the shading data were provided and means for storing in said storage means to the electronic camera, as well as the mode of the electronic camera in the shading data generating mode, the solid in a state in which arranged the display surface of the front liver Nita is opposed to the solid-state imaging device at a predetermined distance from the light receiving surface of the imaging device was irradiated with light emitted from the display surface of the monitor to the solid- There is provided a shading data generation method characterized in that the shading data is generated by photographing .

  According to the present invention, the solid-state image sensor is irradiated with uniform light using the monitor provided in the photographing apparatus. In other words, a display surface of a monitor that can be moved to a position away from the light receiving surface of the solid-state image sensor is arranged to face the solid-state image sensor, and light emitted from the display surface of the monitor is irradiated to the solid-state image sensor. Accordingly, it is possible to easily generate shading data without using separate illumination means for generating shading data. In addition, the apparatus configuration can be simplified.

  The invention according to claim 3 is characterized in that, in order to achieve the object, the shading data is generated for each color temperature by changing the color temperature of the light emitted from the light emitting surface of the monitor. A shading data generation method described in 2 is provided.

According to the present invention, the shading data is generated for each color temperature by changing the color temperature of the light emitted from the light emitting surface of the monitor.
The invention according to claim 4 is characterized in that, in order to achieve the object, the shading data is generated for each color temperature by changing the color temperature of the strobe light emitted from the strobe. The shading data generation method described in 1. is provided.
The invention according to claim 5 is characterized in that, in order to achieve the object, the shading data is generated for each focal length by changing the focal length. The shading data generation method described in 1. is provided.
Moreover, in order to achieve the object, the invention according to claim 6 changes the aperture value and generates the shading data for each aperture value. The shading data generation method described in 1. is provided.

  According to the shading data generation method according to the present invention, it is possible to easily generate shading data.

  The best mode for carrying out a shading data generation method according to the present invention will be described below with reference to the accompanying drawings.

  1 and 2 are a front perspective view and a rear perspective view of an electronic camera in which the shading data generation method according to the present invention is used, respectively.

  As shown in the figure, the camera body 12 of the electronic camera 10 is formed in a square box shape, and a photographing lens 14, a finder window 16 and the like are provided on the front surface thereof. Further, a shutter button 18, a flash 20, a power / mode switch 22 and the like are provided on the upper surface of the camera body 12, and a finder eyepiece 24, a liquid crystal monitor 26, a zoom button 28, a cross button 30, A MENU / OK button 32, a DISP button 34, a BACK button 36, a strobe button 38, and the like are provided. A camera body 12 (not shown) is provided with a tripod screw hole for mounting on a tripod and a battery and memory card loading section on the bottom surface.

  The shutter button 18 is constituted by a two-stage stroke type switch composed of so-called “half press” and “full press”. In the electronic camera 10, AE / AF is activated when the shutter button 18 is “half-pressed”, and shooting is performed when the shutter button 18 is “fully pressed”.

  The strobe 20 is provided so as to protrude and retract from the upper surface of the camera body 12, and pops up from the upper surface of the camera body 12 by pressing the strobe button 38.

  The power / mode switch 22 has a function as a power switch for turning on / off the power of the electronic camera 10 and a function as a mode switch for setting the mode of the electronic camera 10. It is slidably provided between “position” and “photographing position”. The electronic camera 10 is turned on when the power / mode switch 22 is set to the “reproduction position” or “shooting position”, and is turned off when the power is turned to the “OFF position”. Then, by setting the power / mode switch 22 to “playback position”, the “playback mode” is set, and by setting to “shooting position”, the “shooting mode” is set.

  The liquid crystal monitor 26 is composed of a liquid crystal display capable of color display. The liquid crystal monitor 26 is used as an image display panel for displaying a captured image in the reproduction mode, and is used as a user interface display panel in various settings. Further, at the time of shooting, a through image is displayed as necessary, and is used as an electronic viewfinder for checking the angle of view.

  The zoom button 28 includes a zoom tele button 28T for instructing zooming to the telephoto side, and a zoom wide button 28W for instructing zooming to the wide-angle side. Changes.

  The cross button 30 functions as direction instruction means for inputting instructions in four directions, up, down, left, and right, and is used, for example, for selecting a menu item on a menu screen.

  The MENU / OK button 32 has both a function as a MENU button for instructing transition from the normal screen to the menu screen in each mode, and a function as an OK button for instructing selection confirmation, execution of processing, and the like.

  The DISP button 34 functions as a button for instructing switching of the display contents of the liquid crystal monitor 26, and the BACK button 36 functions as a button for instructing cancellation of an input operation or the like.

  FIG. 3 is a block diagram showing an electrical configuration of the electronic camera 10. As shown in the figure, the overall operation of the electronic camera 10 is comprehensively controlled by a central processing unit (CPU) 110. CPU 110 receives operation signals input from operation unit 112 (shutter button 18, power / mode switch 22, zoom button 28, cross button 30, MENU / OK button 32, DISP button 34, BACK button 36, strobe button 38, etc.). Each part is controlled according to a predetermined control program. The ROM 116 connected to the CPU 110 via the bus 114 stores a control program executed by the CPU 110 and various data necessary for the control. The EEPROM 118 relates to the operation of the electronic camera 10 such as user setting information. Various setting information and the like are stored. The memory (SDRAM) 120 is used as a calculation work area for the CPU 110 and is used as a temporary storage area for image data and the VRAM 122 is used as a temporary storage area dedicated to image data.

  The solid-state imaging device 124 is composed of a color CCD, and a large number of photodiodes (light receiving devices) constituting pixels are two-dimensionally arranged on the light receiving surface thereof. Each photodiode is provided with red (R), green (G), and blue (B) color filters so as to form a predetermined array structure (for example, a Bayer array). Light incident on the photographic lens 14 and passed through the aperture 15 is received by each photodiode through this color filter. Each photodiode converts the signal charge into an amount corresponding to the amount of incident light.

  The signal charge accumulated in each photodiode is sequentially read out as a voltage signal (image signal) corresponding to the signal charge based on the drive pulse supplied from the timing generator (TG) 126, and is analog processing section (CDS / AMP). 128.

  The analog processing unit 128 performs sampling hold (correlated double sampling processing) and amplifies the R, G, and B signals for each pixel output from the CCD 124, and outputs them to the A / D converter 130.

  The A / D converter 130 converts the analog R, G, and B signals output from the analog processing unit 128 into digital R, G, and B signals and outputs them to the image input controller 132.

  The image input controller 132 takes in digital R, G, and B signals output from the A / D converter 130 and stores them in the memory 120.

  The image signal processing circuit 134 processes the digital R, G, and B signals stored in the memory 120 in accordance with an instruction from the CPU 110 to generate a luminance signal (Y signal) and a color difference signal (Cr, Cb signal). That is, the image signal processing circuit 134 includes a synchronization circuit (a processing circuit that interpolates a spatial shift of the color signal associated with the color filter array of the single-plate CCD and converts the color signal into a simultaneous expression), a shading correction circuit ( Image processing means including a processing circuit for correcting an output difference due to a difference in sensitivity between each pixel of the CCD according to predetermined shading data, a white balance correction circuit, a gamma correction circuit, a contour correction circuit, a luminance / color difference signal generation circuit, and the like It functions to generate a luminance signal and a color difference signal (luminance / color difference signal) by performing signal processing on R, G, and B signals input in accordance with a command from the CPU 110.

  The procedure of the shading correction process performed by the image signal processing circuit 134 and the generation method of the shading data used for the shading correction will be described in detail later.

  When displaying an image on the liquid crystal monitor 26, the luminance / color difference signal generated by the image signal processing circuit 134 is output to the video encoder 136 via the VRAM 122. The video encoder 136 converts the input luminance / color difference signal into a display signal format (for example, an NTSC color composite video signal) and outputs it to the liquid crystal monitor 26. As a result, an image is displayed on the liquid crystal monitor 26.

  Further, the image signal is periodically taken from the CCD 124, the luminance / color difference signal in the VRAM 122 is periodically rewritten by the luminance / color difference signal generated from the image signal, and is output to the liquid crystal monitor 26 via the video encoder 136. As a result, the real-time image captured by the CCD 124 is output and displayed on the liquid crystal monitor 26.

  As described above, in the electronic camera 10, the AE / AF is activated when the shutter button 18 is “half-pressed”. When the shutter button 18 is half-pressed, an S1 ON signal is input to the CPU 110, and the CPU 110 executes AE / AF processing in response to the S1 ON signal.

  First, an image signal output from the CCD 124 is captured from the image input controller 132 and applied to the AF detection circuit 140 and the AE / AWB detection circuit 142.

  The AE / AWB detection circuit 142 includes a circuit that divides one screen into a plurality of areas (for example, 16 × 16) and accumulates R, G, and B signals for each divided area, and provides the accumulated value to the CPU 110. . The CPU 110 detects the brightness of the subject (subject brightness) based on the integrated value obtained from the AE / AWB detection circuit 142, and calculates an exposure value (shooting EV value) suitable for shooting. Then, an aperture value and a shutter speed are determined from the obtained shooting EV value and a predetermined program diagram.

  The AE / AWB detection circuit 142 calculates an average integrated value for each color of the R, G, and B signals for each divided area during automatic white balance adjustment, and provides the calculation result to the CPU 110. The CPU 110 obtains the ratio of R / G and B / G for each divided area from the obtained integrated value of R, integrated value of B, and integrated value of G, and calculates the R / G and B / G values obtained. The light source type is determined based on the distribution in the color space of R / G and B / G. Then, according to the white balance adjustment value suitable for the determined light source type, for example, the value of each ratio is approximately 1 (that is, the RGB integration ratio is R: G: B≈1: 1: 1 in one screen). In addition, the gain value (white balance correction value) for the R, G, and B signals of the white balance adjustment circuit is controlled to correct the signal of each color channel.

  The AF detection circuit 140 includes a high-pass filter that passes only high-frequency components of the G signal, an absolute value processing unit, an AF area extraction unit that extracts a signal within a predetermined focus area (for example, the center of the screen), and an absolute value within the AF area. The CPU 110 is notified of the integrated value data obtained by the AF detection circuit 140. The CPU 110 calculates a focus evaluation value (AF evaluation value) at a plurality of AF detection points while moving the focus lens group of the photographing lens 14 by controlling the lens driving unit 146, and determines a lens position where the evaluation value is maximized. Determined as the in-focus position. Then, the lens driving unit 146 is controlled so that the focus lens group moves to the obtained in-focus position.

  The photographer operates the zoom button 28 as necessary to zoom the photographing lens 14 and adjust the photographing angle of view. When the zoom tele button 28T is pressed, the CPU 110 controls the lens driving unit 146 in response to the operation amount of the zoom tele button 28T and moves the zoom lens group of the photographing lens 14 to the tele side. When the zoom wide button 28W is pressed, the CPU 110 controls the lens driving unit 146 in response to the operation amount of the zoom wide button 28W to move the zoom lens group of the photographing lens 14 to the wide side.

  Thereafter, when the shutter button 18 is fully pressed, an S2 on signal is input to the CPU 110, and the CPU 110 executes shooting and recording processing in response to the S2 on signal.

  First, the aperture driving unit 144 and the electronic shutter of the CCD 124 are controlled to expose the CCD 124 with the aperture value and shutter speed determined by the AE process. At this time, the CPU 110 sends a command to the strobe control circuit 154 as necessary to cause the strobe 20 to emit light.

  An image signal obtained from the CCD 124 is taken into the memory 120 from the image input controller 132 via the analog processing unit 128 and the A / D converter 130.

  The image signal taken into the memory 120 is added to the image signal processing circuit 134 and subjected to predetermined signal processing to generate image data (luminance / color difference signal). The generated image data is temporarily stored in the memory 120 and then added to the compression / decompression circuit 148.

  The compression / decompression circuit 148 compresses the input image data in accordance with a predetermined compression format (for example, JPEG format). The compressed image data is stored again in the memory 120, converted into an image file of a predetermined image recording format (for example, Exif format), and then recorded on the storage medium (memory card) 152 via the media controller 150. .

  The image recorded on the storage medium 152 as described above is reproduced and displayed on the liquid crystal monitor 26 by setting the mode of the electronic camera 10 to the reproduction mode.

  When the power / mode switch 22 is set to the playback position and the mode of the electronic camera 10 is set to the playback mode, the CPU 110 outputs a command to the media controller 150 and reads the image file recorded last on the storage medium 152. Let

  The compressed image data of the read image file is added to the compression / decompression circuit 148, decompressed to an uncompressed luminance / color difference signal, and then output to the liquid crystal monitor 26 via the video encoder 136. As a result, the image recorded on the storage medium 152 is reproduced and displayed on the liquid crystal monitor 26.

  The frame advance of the image is performed by pressing the right key and the left key of the cross button 30, and when the right key of the cross button 30 is pressed, the image data of the next image file is read from the storage medium 152, and the liquid crystal Reproduced and displayed on the monitor 26. When the left key of the cross button 30 is pressed, the image data of the previous image file is read from the storage medium 152 and reproduced and displayed on the liquid crystal monitor 26.

  As described above, in the electronic camera 10 according to the present embodiment, the image signal processing circuit 134 performs shading correction on the captured image signal (imaging data). Shading correction is performed by correcting imaging data based on predetermined shading data, and the shading data is generated by the following procedure.

  The generation of the shading data is performed by setting the mode of the electronic camera 10 to the “shading data generation mode”. This “shading data generation mode” is called from the shooting menu under the shooting mode. That is, when the MENU / OK button 32 is pressed under the shooting mode to call up the shooting menu, the shooting menu is displayed on the liquid crystal monitor 26. From the menu items that appear in the shooting menu, “generate shading data” is displayed. Select and execute the item. Thereby, the mode of the electronic camera 10 is set to the “shading data generation mode”.

  Here, the shading data is irradiated with strobe light from the strobe 20 provided in the electronic camera 10 toward the diffusion plate 160 installed in front of the camera body 12 under the above-described shading data generation mode, and the reflected light thereof. Is generated by exposing the CCD to the CCD.

  As shown in FIG. 4, the diffusing plate 160 is installed at a position away from the light receiving surface of the CCD 124 by a predetermined distance (D) so that the vicinity of the center portion is imaged on the entire surface of the CCD 124.

  An image signal (imaging data) output from the CCD 124 by exposure is taken into the memory 120 from the image input controller 132 via the analog processing circuit 128 and the A / D converter 130 and added to the shading data generation circuit 156.

The shading data generation circuit 156 generates shading data based on the input imaging data and reference data recorded in advance in the ROM 116. The reference data is generated based on the spectral characteristics (known) of the strobe light emitted from the strobe 20 provided in the electronic camera 10 and stored in the ROM 116. The shading data generation circuit 156 includes the reference data (r (x, y), g (x, y), b (x, y)) for each pixel and the input image data (R _S (x, y)). ), G _S (x, y), B _S (x, y)) and shading data (δ _R (x, y) = r (x, y) / R _S (x, y), δ _G ( x, y) = g (x, y) / G _S (x, y) and δ _B (x, y) = b (x, y) / B _S (x, y)) are generated.

The generated shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) is stored in the EEPROM 118. The image signal processing circuit 134 multiplies the imaging data by the shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) recorded in the EEPROM 118 to correct the shading. I do.

  FIG. 5 is a flowchart showing a procedure of the shading data generation process.

  First, the CPU 110 determines whether or not the camera mode is set to the shading data generation mode (step S11).

  If it is determined that the camera mode is set to the shading data generation mode, preparation for shooting for generating shading data is performed (step S12). That is, the strobe 20 is popped up and the photographing lens 14 is zoomed to set a predetermined focal length.

  On the other hand, the photographer fixes the camera body 12 to a tripod or the like and installs the diffusion plate 162 at a predetermined position (a position away from the light receiving surface of the CCD 124).

  Thereafter, the CPU 110 determines whether or not the shutter button 18 is fully pressed (step S13). If it is determined that the shutter button 18 is fully pressed, the flash 20 is caused to emit light (step S14), and a predetermined shutter speed and aperture value are determined. Then, the CCD 124 is exposed (step S15).

Imaging data obtained by exposure is taken into the memory 120 and added to the shading data generation circuit 156. The shading data generation circuit 156 records the imaging data (R _S (x, y), G _S (x, y), B _S (x, y)) obtained as described above in the ROM 116 in advance. Based on the reference data (r (x, y), g (x, y), b (x, y)), shading data (δ _R (x, y), δ _G (x, y), δ _B ( x, y)) is generated (step S16).

Then, the generated shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) is stored in the EEPROM 118 (step S17).

  FIG. 6 is a flowchart showing a procedure of imaging and recording processing of imaging data including shading correction.

  First, the CPU 110 determines whether or not the camera mode is set to the shooting mode (step S21).

  If it is determined that the camera mode is set to the shooting mode, it is determined whether or not the shutter button 18 is half-pressed (step S22). If it is determined that the shutter button 18 is half-pressed, AE / AF processing is performed (step S22). Step S23). Thereafter, it is determined whether or not the shutter button 18 is fully pressed (step S24). If it is determined that the shutter button 18 is fully pressed, the CCD 124 is exposed to image data (R (x, y), G (x, y) and B (x, y)) are acquired (step S25).

  The imaging data (R (x, y), G (x, y), B (x, y)) obtained from the CCD 124 is subjected to various signal processing including shading correction in the image signal processing circuit 134. (Step S26), the data is compressed by the compression / decompression circuit 148 and recorded on the storage medium 152 (Step S27).

Here, the shading correction is performed using the shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) recorded in the EEPROM 118, and this shading data (δ _{R (x, y), δ} G (x, y), δ B (x, y)) the imaging data (R (x, y), G (x, y), B (x, y) multiplied by) Is done.

  FIGS. 7A and 7B show changes in imaging data before and after shading correction. FIG. 7A shows a state before correction and FIG. 7B shows a state after correction. The graph is obtained by standardizing image-captured image data for each of R, G, and B with a luminance level. As shown in the figure, variations in R, G, and B luminance levels that occurred before correction are corrected by executing shading correction.

  As described above, according to the electronic camera 10 of the present embodiment, since the strobe 20 provided in the electronic camera 10 is used as a light source for generating shading data, it is necessary to prepare a separate light source for generating shading data. Therefore, shading data can be generated easily.

  In this embodiment, the shading data is generated based on the imaging data captured under a predetermined aperture value and focal length. However, the shading data is generated for each settable aperture value and focal length. May be. Then, the imaging data may be subjected to shading correction based on the shading data generated for each aperture value / focal length acquired in this way.

  For example, in the case of an electronic camera in which the aperture value can be switched between F2.8 and F8.0, shading data is generated based on the imaging data captured at F2.8, and shading is performed based on the imaging data captured at F8.0. Generate data. At the time of shooting, the imaging data is subjected to shading correction based on the shading data of the aperture value that has been shot. That is, when shooting at F2.8, the imaging data is shading corrected based on the shading data of F2.8, and when shooting at F8.0, the imaging data is shading corrected based on the shading data of F8.0. To do.

  Similarly, when the photographing lens is an electronic camera having a zoom lens, shading data is generated based on imaging data acquired by changing the focal length in predetermined steps. And at the time of imaging | photography, shading correction | amendment of imaging data is carried out using the shading data according to a focal distance.

  In addition, in the case of an electronic camera that can change both the aperture and the focal length, shading data is generated for each aperture value and focal length, and imaging data is generated based on the generated aperture value and shading data for each focal length. Correct shading.

  In this way, more accurate shading correction can be performed by generating shading data for each aperture value and focal length, and correcting the imaging data based on the generated shading data.

  Next, a second embodiment of the shading data generation method according to the present invention will be described.

  8 and 9 are respectively a front perspective view and a rear perspective view of the electronic camera 200 used in the shading data generation method according to the second embodiment.

  As shown in the figure, a liquid crystal monitor is movably provided in the electronic camera 200 used in the shading data generation method of the second embodiment. The configuration other than the liquid crystal monitor is the same as that of the electronic camera 10 used in the shading data generation method of the first embodiment described above. Accordingly, the same members are denoted by the same reference numerals, and the description thereof is omitted.

  The liquid crystal monitor 202 is attached to the camera body 12 via the arm 204. The arm 202 mainly includes an arm main body 204A, a vertical rotation shaft 204B, and a horizontal rotation shaft 204C.

Arm body 204A is positioned accommodated in a recess 206 formed in the side surface of the camera body 12, is supported by a shaft (not shown) the proximal end swingably supported perpendicular about the axis V ₁ Has been.

Vertical rotation shaft 204B is positioned accommodated in a recess 208 formed in the distal end of the arm body 204A, and a vertical axis V ₂ around is rotatably supported.

  The horizontal rotation shaft 204C is disposed so as to protrude from the outer peripheral surface of the vertical rotation shaft 204B, and is supported so as to be rotatable around a horizontal axis H. The liquid crystal monitor 202 is attached to the tip of the horizontal rotation shaft 204C.

The liquid crystal monitor 202 can be swung around the axis V ₁ by swinging the arm main body 204A, and the horizontal direction of the display surface can be changed by rotating the vertical rotation shaft 204B. Further, the vertical direction of the display surface can be changed by rotating the horizontal rotating shaft 204C.

  Now, in the electronic camera 200 configured as described above, generation of shading data is performed as follows.

  The generation of shading data is performed by setting the mode of the electronic camera 10 to the “shading data generation mode” as in the first embodiment. The setting of “shading data generation mode” is the same as that in the first embodiment. That is, when the MENU / OK button 32 is pressed under the shooting mode to call up the shooting menu, the shooting menu is displayed on the liquid crystal monitor 26. From the menu items that appear in the shooting menu, “generate shading data” is displayed. Select and execute the item.

  After setting the shading data generation mode, the user changes the orientation of the liquid crystal monitor 202 as shown in FIG. 10 so that the display surface of the liquid crystal monitor 202 is in close contact with the tip of the photographing lens 14. Thereby, the display surface of the liquid crystal monitor 202 is installed so as to face the CCD 124.

  The shading data is generated by irradiating light of a specific color temperature and luminance from the liquid crystal monitor 202 and exposing the light to the CCD 124.

  An image signal (imaging data) output from the CCD 124 by exposure is taken into the memory 120 from the image input controller 132 via the analog processing circuit 128 and the A / D converter 130 and added to the shading data generation circuit 156.

The shading data generation circuit 156 generates shading data based on the input imaging data and reference data recorded in advance in the ROM 116. This reference data is generated based on the spectral characteristics (known) of the light emitted from the liquid crystal monitor 202 and stored in the ROM 116. The shading data generation circuit 156 includes the reference data (r (x, y), g (x, y), b (x, y)) for each pixel and the input image data (R _S (x, y)). ), G _S (x, y), B _S (x, y)) and shading data (δ _R (x, y) = r (x, y) / R _S (x, y), δ _G ( x, y) = g (x, y) / G _S (x, y) and δ _B (x, y) = b (x, y) / B _S (x, y)) are generated.

The generated shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) is stored in the EEPROM 118. The image signal processing circuit 134 multiplies the imaging data by the shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) recorded in the EEPROM 118 to correct the shading. I do.

  FIG. 11 is a flowchart showing a procedure of the shading data generation process.

  First, the CPU 110 determines whether or not the camera mode is set to the shading data generation mode (step S31).

  If it is determined that the camera mode is set to the shading data generation mode, preparation for shooting for generating shading data is performed (step S32). That is, the photographing lens 14 is zoomed and set to a predetermined focal length, and the liquid crystal monitor 202 is caused to emit light at a predetermined luminance and color temperature.

  On the other hand, the user changes the direction of the display surface of the liquid crystal monitor 202 and installs the display surface so as to contact the front end surface of the photographing lens 14. That is, the display surface of the liquid crystal monitor 202 is installed so as to face the CCD 124.

  Thereafter, the CPU 110 determines whether or not the shutter button 18 is fully pressed (step S33), and if it is determined that the shutter button 18 is fully pressed, the CCD 124 is exposed with a predetermined shutter speed and aperture value (step S34).

Imaging data obtained by exposure is taken into the memory 120 and added to the shading data generation circuit 156. The shading data generation circuit 156 records the imaging data (R _S (x, y), G _S (x, y), B _S (x, y)) obtained as described above in the ROM 116 in advance. Based on the reference data (r (x, y), g (x, y), b (x, y)), shading data (δ _R (x, y), δ _G (x, y), δ _B ( x, y)) is generated (step S35).

Then, the generated shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) is stored in the EEPROM 118 (step S36).

At the time of shooting, the imaging data is subjected to shading correction based on the shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) generated as described above. That is, the shading data (δ _R (x, y), δ _G (x, y), δ _B (x, y)) recorded in the EEPROM 118 is captured by the image data (R (x, y) in the image signal processing circuit. ), G (x, y), B (x, y)), and shading correction is performed (see FIGS. 6 and 7).

  As described above, according to the electronic camera 10 of the present embodiment, since the liquid crystal monitor 202 provided in the electronic camera 10 is used as a light source for generating shading data, it is necessary to prepare a light source for generating shading data separately. No shading data can be generated easily.

  In the present embodiment, the shading data is generated based on the imaging data imaged under a predetermined aperture value and focal length. However, as in the first embodiment, for each aperture value and focal length. Shading data may be generated, and imaging data may be subjected to shading correction based on the generated shading data. Thereby, more accurate shading correction can be performed.

  In this embodiment, shading data is generated by irradiating light of a predetermined color temperature from the liquid crystal monitor 202. By changing the color temperature of the irradiated liquid crystal monitor 202, the shading data is changed for each color temperature. May be generated, and the imaging data may be subjected to shading correction based on the generated shading data for each color temperature. That is, shading correction is performed using shading data having a color temperature corresponding to the color temperature at the time of shooting. Thereby, more accurate shading correction can be performed.

  When a strobe capable of changing the color temperature, for example, a strobe using an LED as a light source is used, the shading data is generated for each color temperature in the shading data generation method of the first embodiment. May be.

  In the above embodiment, the case where the present invention is applied to an electronic camera that captures a still image has been described as an example. However, the present invention can also be applied to other imaging devices such as a video camera.

  In the above embodiment, the case where the present invention is applied to an electronic camera using a CCD as an image sensor has been described as an example. However, the present invention can be similarly applied to a case where another image sensor is used.

1 is a front perspective view of an electronic camera in which a shading data generation method according to the present invention is used (first embodiment). 1 is a rear perspective view of an electronic camera using a shading data generation method according to the present invention (first embodiment). 1 is a block diagram showing an electrical configuration of the electronic camera shown in FIG. Side view showing the state of the electronic camera in the shading data generation mode Flow chart showing the procedure of shading data generation processing Flow chart showing the procedure of shading correction processing Diagram showing changes in imaging data before and after shading correction Front perspective view of an electronic camera in which the shading data generation method according to the present invention is used Front perspective view of an electronic camera in which the shading data generation method according to the present invention is used Plan view showing the state of the electronic camera in the shading data generation mode Flow chart showing the procedure of shading data generation processing

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Electronic camera, 12 ... Camera body, 14 ... Shooting lens, 16 ... Viewfinder window, 18 ... Shutter button, 20 ... Strobe, 22 ... Power supply / mode switch, 24 ... Viewfinder eyepiece, 26 ... LCD monitor, 28 ... Zoom button, 30 ... cross button, 32 ... MENU / OK button, 34 ... DISP button, 36 ... BACK button, 38 ... strobe button, 110 ... central processing unit (CPU), 112 ... operation unit, 114 ... bus, 116 ... ROM, 118 ... EEPROM, 120 ... Memory (SDRAM), 122 ... VRAM, 124 ... Solid-state imaging device (CCD), 126 ... Timing generator (TG), 128 ... Analog processing unit (CDS / AMP), 130 ... A / D Converter 132 ... Image input controller 134 ... Image signal processing circuit 136 ... Deo encoder 140 ... AF detection circuit 142 ... AE / AWB detection circuit 144 ... Aperture drive unit 146 ... Lens drive unit 148 ... Compression / decompression circuit 150 ... Media controller 152 ... Storage medium (memory card) 154 ... Strobe control circuit, 156 ... Shading data generation circuit, 160 ... Diffuser, 200 ... Electronic camera, 202 ... Liquid crystal monitor, 204 ... Arm, 204A ... Arm body, 204B ... Vertical rotation axis, 204C ... Horizontal rotation axis, 206 ... Recess, 208 ... Recess

Claims (6)

A shading data generation method for generating shading data to be stored in the storage means in an electronic camera that performs shading correction on the image data obtained from the solid-state imaging device using the shading data stored in the storage means. And
When the mode is set to the shading data generation mode, when the mode is set to the shading data generation mode, the shooting is instructed in the state of the shading data generation mode and the means for setting the photographing lens to a predetermined focal length. Then, means for emitting strobe light from the strobe and exposing the solid-state imaging device at a predetermined shutter speed and aperture value, means for generating shading data from the image data obtained by the exposure, and Means for storing the shading data in the storage means in the electronic camera;
The mode of the electronic camera is set to the shading data generation mode, and the shading data is generated by photographing the diffusion plate installed at a predetermined distance from the light receiving surface of the solid-state imaging device. Shading data generation method. A shading data generation method for generating shading data to be stored in the storage means in an electronic camera that performs shading correction on the image data obtained from the solid-state imaging device using the shading data stored in the storage means. And
A movable monitor, means for setting the mode to a shading data generation mode, and when the mode is set to the shading data generation mode, the photographing lens is set to a predetermined focal length, and the monitor is set to a predetermined luminance. From a means for emitting light at a color temperature, a means for exposing the solid-state imaging device at a predetermined shutter speed and aperture value when photographing is instructed in the state of the shading data generation mode, and image data obtained by the exposure The electronic camera is provided with means for generating shading data and means for storing the generated shading data in the storage means,
Wherein with the electronic camera mode to the shading data generation mode, arranged to display surface before liver Nita is opposed to the solid-state imaging device at a predetermined distance from the light-receiving surface of the solid-state imaging device, said monitor A shading data generation method comprising: generating the shading data by photographing in a state where the solid-state imaging device is irradiated with light emitted from the display surface.   The shading data generation method according to claim 2, wherein the shading data is generated for each color temperature by changing a color temperature of light emitted from the light emitting surface of the monitor. 2. The shading data generation method according to claim 1, wherein the shading data is generated for each color temperature by changing a color temperature of the strobe light emitted from the strobe. The shading data generation method according to any one of claims 1 to 4, wherein the shading data is generated for each focal length by changing the focal length. The shading data generation method according to claim 1, wherein the shading data is generated for each aperture value by changing the aperture value.

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