JP2012039271A - Imaging apparatus and image reproduction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus and an image reproduction apparatus which are capable of improving visibility of an image display unit when luminance is high.SOLUTION: An imaging sensor 9 and an image processing unit 15 receive subject light and repeat generation of a display image signal (S31); detect the luminance of external light with an external light sensor 35 and determine whether the luminance of the external light is not lower than a predetermined luminance (S39); when determining the luminance of the external light is lower than the predetermined luminance, subject the display image signal to gamma correction with a gamma curve, generate a second display image signal, and display the second display image signal (S97); when determining the luminance of the external light is not lower than the predetermined luminance, subject the display image signal to gamma correction with a gamma curve having offset (S91), generate a second display image signal, and display the second display image signal (S93).

Description

  The present invention relates to an imaging device and an image reproduction device, and more particularly, to an imaging device and an image reproduction device having an image display unit that displays a captured image.

  2. Description of the Related Art There is known an imaging apparatus that includes an image display unit that displays an image on a display such as a liquid crystal display (LCD (Liquid Crystal Display)) and that can check a captured image. In such an imaging apparatus, when shooting is performed in a situation where the brightness of outside light is high, such as outdoors, there is a problem that the visibility of the captured image is reduced on the display unit and is difficult to confirm.

  In order to solve such a problem, Patent Document 1 proposes an imaging apparatus in which the luminance of the backlight of the LCD is increased when the ambient external light luminance is high. Patent Document 2 proposes a portable device that improves the visibility by raising the gradation characteristics of the intermediate gradation region when the ambient external light luminance is high.

JP-A-8-242398 JP 2005-323175 A

  As described above, various proposals have been made to improve the visibility of the image display unit when the external light luminance is high, but it is difficult to say that it is sufficient. In other words, the imaging device disclosed in Patent Document 1 has a limit in increasing the luminance of the backlight, and the portable device disclosed in Patent Document 2 cannot improve the gradation characteristics of the intermediate gradation region. There is a limit. For this reason, there is a problem that the effect of improving the visibility of the display unit is small under high brightness external light such as outdoors in fine weather.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an imaging device and an image reproduction device capable of improving the visibility of an image display unit at high luminance.

  In order to achieve the above object, an image pickup apparatus according to a first invention is an image pickup apparatus that picks up a subject and generates an image signal, receives the subject light, repeatedly generates a display image signal, and issues a shooting instruction. An imaging unit that receives and generates an image signal for recording, an external light luminance determination unit that detects the luminance of external light and determines whether the external light luminance is equal to or higher than a predetermined luminance, and a display generated by the imaging unit A display control unit that generates a second display image signal using a gamma curve with respect to the image signal for display, and a display unit that displays a live view image based on the second display image signal output from the display control unit And the display control unit determines that the gamma is applied to the display image signal generated by the imaging unit when the external light luminance determination unit determines that the external light luminance is equal to or higher than the predetermined luminance. Offset the curve Generating a second display image.

  An image pickup apparatus according to a second aspect of the present invention includes, in the first aspect, an image brightness determination unit that determines whether the display image has a predetermined brightness or more based on the display image signal. The display control unit is generated by the imaging unit when the external light luminance determined by the external light luminance determination unit is determined to be equal to or higher than the predetermined luminance and the display image is determined to be higher than the predetermined luminance by the image lightness determination unit. A second display image is created by offsetting the gamma curve with respect to the displayed display image signal.

According to a third aspect of the present invention, there is provided the imaging apparatus according to the second aspect, wherein the image brightness determination unit is configured such that a predetermined luminance or less exceeds a predetermined number in a histogram of luminance distribution of pixel signals constituting the display image. It is determined that the brightness is equal to or higher than the predetermined brightness.
According to a fourth aspect of the present invention, there is provided the imaging apparatus according to the second aspect, wherein the image brightness determination unit is predetermined when an average value of luminance distributions of pixel signals constituting the display image is equal to or lower than a predetermined luminance. It is determined that the brightness is greater than or equal to the brightness.

  An imaging apparatus according to a fifth invention includes a face detection unit that detects a face from an image signal output from the imaging unit and determines a face area in the second invention, and the image brightness determination unit includes: When the predetermined luminance or lower exceeds a predetermined number in the histogram of the luminance distribution of the pixel signal constituting the face area detected by the face detection portion in the display image, it is determined that the luminance is equal to or higher than the predetermined brightness.

  An imaging apparatus according to a sixth invention is the imaging apparatus according to the second invention, wherein the imaging apparatus includes an AF unit that sets a focus area based on an image signal output from the imaging unit and performs an AF operation. The image brightness determination unit includes: When the predetermined luminance or lower exceeds a predetermined number in the histogram of the luminance distribution of the pixel signal constituting the focus area set by the AF section in the display image, it is determined that the predetermined luminance or higher.

  According to a seventh aspect of the present invention, there is provided the imaging apparatus according to the first aspect, wherein the display unit includes a backlight unit, and the control unit performs the gamma curve with respect to the display image signal generated by the imaging unit. When the second display image is created by offsetting the display, the display control unit reduces the power supplied to the backlight unit.

  An image pickup apparatus according to an eighth aspect of the invention is an image pickup apparatus that picks up a subject and generates an image signal, receives the subject light, repeatedly generates a display image signal, receives a shooting instruction, and receives a recording instruction. A display control unit that creates a second display image signal using a gamma curve for the display image signal generated by the imaging unit, and a second output from the display control unit A display unit that displays a live view image based on the display image signal, and the display control unit is generated by the imaging unit when the current consumption of the display unit is determined to be a predetermined value or more. A second display image is created by offsetting the gamma curve with respect to the display image signal.

  According to a ninth aspect of the present invention, there is provided an image reproducing device for reproducing and displaying a recorded image signal, wherein the recording unit for recording the image signal and the luminance of the external light are detected and the external light luminance is a predetermined luminance. An external light luminance determination unit that determines whether or not the above is satisfied, a display control unit that generates a second display image signal using a gamma curve for the display image signal output from the recording unit, and the display control A display unit that displays a reproduced image based on a second display image signal output from the unit, and wherein the display control unit has determined that the external light luminance is greater than or equal to the predetermined luminance by the external light luminance determination unit In this case, a second display image is created by offsetting the gamma curve with respect to the display image signal output from the recording unit.

  An image reproduction apparatus according to a tenth invention includes, in the ninth invention, an image brightness determination unit that determines whether the display image has a predetermined brightness or more based on the display image signal. When the external light luminance determination unit determines that the external light luminance is equal to or higher than the predetermined luminance and the image lightness determination unit determines that the display image is equal to or higher than the predetermined lightness, the display control unit A second display image is created by offsetting the gamma curve with respect to the output display image signal.

According to an eleventh aspect of the present invention, in the image reproduction apparatus according to the tenth aspect, the image brightness determination unit includes a case where a predetermined luminance or less exceeds a predetermined number in a histogram of the luminance distribution of the pixel signal constituting the display image. Then, it is determined that the brightness is equal to or higher than a predetermined brightness.
The image reproduction apparatus according to a twelfth aspect of the present invention is the image reproduction apparatus according to the tenth aspect, wherein the image brightness determination unit is configured such that an average value of luminance distributions of pixel signals constituting the display image is equal to or less than a predetermined luminance. It is determined that the brightness is equal to or greater than a predetermined brightness.

  According to a thirteenth aspect of the present invention, in the tenth aspect of the invention, the image reproduction apparatus further includes a face determination recording unit that determines that a face is detected and a face area is determined at the time of shooting based on the image signal output from the recording unit. The image brightness determination unit has a predetermined brightness when a predetermined luminance or less exceeds a predetermined number in the histogram of the luminance distribution of the pixel signal constituting the face area determined by the face determination recording unit in the display image. It is determined as above.

  According to a fourteenth aspect of the present invention, in the tenth aspect of the present invention, the image reproduction apparatus includes a focus area recording unit that determines a focus area set at the time of shooting based on an image signal output from the recording unit. The determination unit determines that the brightness is equal to or higher than a predetermined brightness when a predetermined luminance or less exceeds a predetermined number in a histogram of the luminance distribution of the pixel signal constituting the focus area determined by the focus recording unit in the display image.

  According to a fifteenth aspect of the present invention, in the ninth aspect, the display section includes a backlight section, and the control section performs the above-described display image signal output from the recording section. When the second display image is created by offsetting the gamma curve, the display control unit reduces the power supplied to the backlight unit.

  According to a sixteenth aspect of the present invention, there is provided an image reproducing device for reproducing and displaying a recorded image signal, a recording unit for recording the image signal, and a gamma curve for the display image signal output from the recording unit. A display control unit that generates a second display image signal using the display control unit, and a display unit that displays a reproduction image based on the second display image signal output from the display control unit. The unit creates a second display image by offsetting the gamma curve with respect to the display image signal output from the recording unit when the current consumption of the display unit is determined to be a predetermined value or more. .

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device and image reproduction apparatus which can improve the visibility of an image display part at the time of high brightness | luminance can be provided.

1 is a block diagram illustrating an overall configuration mainly including an electric system of a camera according to a first embodiment of the present invention. It is a flowchart which shows the power-on operation | movement of the camera concerning 1st Embodiment of this invention. It is a flowchart which shows the live view operation | movement of the camera concerning 1st Embodiment of this invention. It is a flowchart which shows the reproduction | regeneration operation | movement of the camera concerning 1st Embodiment of this invention. It is a graph which shows the gamma curve in the camera concerning 1st Embodiment of this invention, and the gamma curve with an offset. It is a flowchart which shows the live view operation | movement of the camera concerning 2nd Embodiment of this invention. It is a flowchart which shows the reproduction | regeneration operation | movement of the camera concerning 2nd Embodiment of this invention. It is a graph which shows an example of the level of a pixel signal in the camera concerning a 2nd embodiment of the present invention. It is a flowchart which shows the live view operation | movement of the camera concerning 3rd Embodiment of this invention. It is a flowchart which shows the reproduction | regeneration operation | movement of the camera concerning 3rd Embodiment of this invention. It is a flowchart which shows the live view operation | movement of the camera concerning 4th Embodiment of this invention. It is a flowchart which shows the reproduction | regeneration operation | movement of the camera concerning 4th Embodiment of this invention. It is a flowchart which shows the live view operation | movement of the camera concerning 5th Embodiment of this invention. It is a flowchart which shows the reproduction | regeneration operation | movement of the camera concerning 5th Embodiment of this invention. It is a block diagram which shows the whole structure mainly consisting of the electric system of the camera concerning 6th Embodiment of this invention. It is a flowchart which shows the live view operation | movement of the camera concerning 6th Embodiment of this invention. It is a flowchart which shows the reproduction | regeneration operation | movement of the camera concerning 6th Embodiment of this invention.

  Hereinafter, a preferred embodiment will be described using a camera to which the present invention is applied according to the drawings. A camera according to a preferred embodiment of the present invention is a digital camera, and includes an imaging unit. The imaging unit converts a subject image into an image signal, and the subject image is converted into an image signal based on the converted image signal. Live view is displayed on the display unit on the back. The photographer determines the composition and shooting timing by observing the live view display. When the shutter is released, an image signal of a still image or a moving image is recorded on the recording medium. When the reproduction mode is selected, the image signal recorded on the recording medium can be read and the image can be reproduced and displayed on the display unit. When live view display or playback display is performed, the external light luminance is measured. When the external light luminance is bright, gamma correction is performed using a gamma curve with an offset when an image is displayed on the display unit.

  FIG. 1 is a block diagram showing an overall configuration mainly including an electric system of a camera according to the first embodiment of the present invention. The photographing lens 1 is composed of a plurality of optical lenses for forming a subject image, and is driven by the AF unit 3 for focus adjustment. The AF unit 3 extracts a high frequency component from an image signal output from an imaging sensor 9 described later, and adjusts the position of the photographing lens 1 so that the high frequency component becomes a peak. A plurality of focus areas of the AF unit 3 are prepared, and the AF unit 3 is selected such as an area where a human face is detected by the face detection unit 17 to be described later, an area where a subject on a short distance side exists, or the like. Focus is performed based on the image signal in the focus area.

  An aperture 5, a shutter 7, and an image sensor 9 are disposed on the optical path of the taking lens 1. The diaphragm 5 adjusts the amount of light of the subject light beam that has passed through the photographing lens 1, and the aperture amount of the diaphragm 5 is driven and controlled by the diaphragm driving mechanism. The shutter 7 opens and closes the subject light flux that has passed through the photographing lens 1, and the shutter opening time (shutter speed) is controlled by the shutter drive mechanism.

  The image sensor 9 photoelectrically converts the subject image formed by the photographing lens 1 and outputs an image signal. Needless to say, the imaging sensor 9 may be a two-dimensional solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

  The imaging sensor 9 is connected to the imaging circuit 11. The imaging circuit 11 reads an image signal from the imaging sensor 9, performs various processes such as amplification, and outputs the image signal to the A / D converter 13. The A / D converter 13 converts an image signal that is an analog signal into an image signal that is a digital signal.

  The output of the A / D conversion 13 is output to the image processing unit 15. The image processing unit 15 performs digital amplification (digital gain adjustment processing), color correction, gamma (γ) correction, contrast correction, black and white / color mode for the image signal A / D converted by the A / D conversion 13. Various image processing such as processing and live view display processing are performed. The image processing unit 15 uses these image processes to generate a display image signal for an image signal output from the imaging sensor 9 or an image signal read from a recording medium 25 described later. The gamma correction is performed on the display image signal so that the input gradation becomes the output gradation along the gamma curve stored in advance, and the image processing unit 15 thereby performs the second display. An image signal is generated. In this embodiment, the gamma curve includes a normal gamma curve and a gamma curve with an offset, and the image processing unit 5 executes gamma correction in accordance with an instruction from the system controller 41.

  The face detection unit 17 receives an image signal from the image processing unit 15 and detects whether or not a face is included in the subject image. If the face is included as a result of the detection, the position and size of the face are detected, and the detection result is output to the system controller 41 described later through the image processing unit 15.

  The buffer memory 19 receives an image signal from the image processing unit 15 and temporarily stores the image signal. The menu image recording unit 21 stores the menu image and outputs it to the buffer memory 19 in accordance with an instruction from the system controller 41. The menu image is a screen image for performing various settings such as a recording mode and white balance.

  The compression / decompression unit 23 receives an image signal from the buffer memory 19 and compresses the image signal using the JPEG method, the TIFF method, or the like. The image compression is not limited to the JPEG method or the TIFF method, and other compression methods can be applied. The recording medium 25 is a recording medium for recording a still image or moving image image signal compressed by the compression / decompression unit 23. When the image signal is recorded, information on the focus area when the AF unit 3 performs focusing is also recorded. Further, the image signal recorded on the recording medium 25 is read out and expanded by the compression / decompression unit 23.

  The liquid crystal controller 27 receives the image signal temporarily stored in the buffer memory 19 and the image signal recorded on the recording medium 25 and expanded by the compression / decompression unit 23. An EVF (Electronic View Finder) 29 is connected to the liquid crystal control unit 27 and displays a subject image based on an image signal. The EVF 29 can observe the liquid crystal screen by looking through the eyepiece.

  Similarly, the liquid crystal control unit 31 receives the image signal temporarily stored in the buffer memory 19 and the image signal recorded on the recording medium 25 and expanded by the compression / decompression unit 23. The TFT 33 is a large-screen liquid crystal panel connected to the liquid crystal control unit 31, and is disposed on the back surface of the camera. Unlike the EVF 29, the user can directly observe the screen without passing through the eyepiece.

  The external light sensor 35 is disposed in the vicinity of the TFT 33 and measures the luminance of external light. The operation unit 37 is an operation member for the user to instruct various operations with respect to the camera. The operation unit 37 includes various operation members such as a release button, a mode dial, a cross key, a confirmation key, a power switch, and a playback button. The operation unit 37 detects the operation states of the various operation members described above and outputs the detection results to the system controller 41.

  The system controller 41 includes the AF unit 3, aperture 5, shutter 7, imaging sensor 9, imaging circuit 11, A / D converter 13, image processing unit 15, menu image recording unit 21, compression / decompression unit 23, and recording medium 25. The liquid crystal control units 27 and 31, the external light sensor 35, and the operation unit 37 are connected. The system controller 41 executes processing according to a program stored in a non-volatile memory such as a flash memory, and controls the operation of the entire camera.

  Next, the operation in the present embodiment will be described with reference to the flowcharts shown in FIGS. These flowcharts are executed by the system controller 41 based on a program stored in the nonvolatile memory. Similarly, the system controller 41 executes the flowcharts in the second to sixth embodiments.

  The camera power-on flow shown in FIG. 2 is a main flow, which starts when a power supply battery is loaded in the camera. When the operation starts, it is first determined whether or not the power switch is on (S1). Here, the on / off state of the power switch in the operation unit 37 is detected and determined.

  If the result of determination in step S1 is that the power switch is not on, a sleep state is entered (S3). The sleep state is a state of a low power consumption mode in which processing other than detecting the operation state of the power switch by interrupt processing is not performed.

  If the power switch is turned on in the sleep state in step S3 or if the result of determination in step S1 is that the power switch is on, then the back panel is turned on and each device is turned on. (S5). Here, power is supplied to the TFT 33 and other circuits (devices) to start the operation. In the present embodiment, the TFT 33 and the EVF 29 are switched by a switching operation member in the operation unit 37, and one of the TFT 33 and the EVF 29 performs a display operation, and the other does not perform a display operation. However, it goes without saying that the TFT 33 and the EVF 29 may be displayed simultaneously.

  Subsequently, a live view operation is performed (S7). In the live view operation, the image signal acquired by the imaging sensor 9 is processed into an image signal for live view display by the image processing unit 15, and live view display is performed by the TFT 33 based on this image signal. The user determines the composition and the shutter timing by observing the live view display. In this live view operation, when the external light luminance is higher than the predetermined luminance, the gamma correction at the time of display on the TFT 33 is performed using a gamma curve with an offset. Detailed operation of the live view operation will be described later with reference to FIG.

  Once the live view operation has been performed, it is next determined whether or not the playback switch is on (S9). When the captured image recorded on the recording medium 25 is reproduced and displayed, the user operates the reproduction button. In this step, it is determined whether or not the reproduction switch linked to the reproduction button of the operation unit 37 is on.

  If the result of determination in step S9 is that the regeneration switch is on, regeneration operation is next carried out (S23). Here, the image signal recorded on the recording medium 25 is read, and the captured image is reproduced on the TFT 33. In this reproduction operation, when the external light luminance is higher than the predetermined luminance, a gamma curve with an offset is used for gamma correction at the time of display on the TFT 33. Detailed operation of this reproduction operation will be described later with reference to FIG.

  If the result of determination in step S9 is that the regeneration switch is not on, it is next determined whether or not the 1R switch is on (S11). When the user performs the shooting preparation operation, the release button in the operation unit 37 is half-pressed. Therefore, in this step, it is determined whether or not the 1R switch linked to the half-press operation of the release button is turned on. .

  If the result of determination in step S11 is that the 1R switch is on, AF operation is executed (S13). In the AF operation, only the high frequency component is extracted from the image signal based on the image signal acquired by the image sensor 9, and the focus position of the photographing lens 1 is adjusted by the AF unit 3 so that the high frequency component becomes a peak.

  Once the AF operation has been performed, it is next determined whether or not the 2R switch is on (S15). As a result of the shooting preparation operation, when the subject is in focus and the composition is intended by the user, the user further pushes the release button to execute the shooting operation. In this step, it is determined whether or not the 2R switch that is linked to the full-pressing operation of the release button is turned on.

  If the result of determination in step S15 is that the 2R switch is not on, processing returns to step S11. On the other hand, if the 2R switch is turned on as a result of the determination, the photographing operation is executed (S17). Here, the image signal acquired by the imaging sensor 9 is A / D converted, image-processed, image-compressed, and the compressed image signal is recorded on the recording medium 25.

  If the shooting operation in step S17 is completed, or if the 1R switch is not turned on as a result of the determination in step S11, or if the reproduction operation in step S23 is performed, then whether the power switch is turned on as in step S1. It is determined whether or not (S19). Here, the on / off state of the power switch in the operation unit 37 is detected and determined.

  If the result of determination in step S19 is that the power switch is on, processing returns to step S7. On the other hand, if the result of determination is that the power switch is off, power off processing is performed (S21). When the power-off process is performed, the process returns to step S3 and enters the sleep state.

  Next, the live view operation in step S7 will be described using the flowchart shown in FIG. When the live view operation is started, an image pickup operation is first performed (S31). Here, an image signal is acquired by the imaging sensor 9.

  Subsequently, an AF operation is performed (S33). Here, a high frequency component is extracted from the image signal based on the image signal acquired by the imaging sensor 9, and the photographing lens 1 is focused by the AF unit 3 so that the extracted high frequency component becomes a peak. .

  Once the AF operation is performed, a photometric operation is performed (S35). Here, the luminance of the subject is obtained based on the image signal acquired by the imaging sensor 9.

  Once the photometric operation is performed, image processing is next performed (S37). Here, based on the image signal acquired by the imaging sensor 9, the image processing unit 15 converts it into an image signal for live view display. In general, the number of pixels of the image sensor 9 is larger than the number of pixels necessary for live view display. Therefore, as image processing in this step, processing such as reducing the number of pixels is performed.

  Once image processing has been performed, it is next determined whether or not 100,000 lx (lux) or more has been detected by the external light sensor (S39). Here, photometry is performed by the external light sensor 35, and it is determined whether or not the photometric value is 100,000 lx or more. Note that the determination value 100,000 lx is a determination value for switching whether or not the gamma curve of the display TFT 33 is to have an offset as will be described later. Therefore, the determination value is appropriately designed according to the display characteristics of the TFT 33. It can be determined as a value.

  If the result of determination in step S39 is that the ambient light brightness by the ambient light sensor 35 is less than 100,000 lx, an image is displayed on the liquid crystal panel using the normal set value gamma curve (S97). In this step, the image signal is gamma-corrected in accordance with a gamma correction 61 that is normally performed, that is, as shown in FIG. The live view image is displayed on the TFT 33.

  On the other hand, as a result of the determination in step S39, when the external light luminance by the external light sensor 35 is 100,000 lx or more, the gamma curve is set to have an offset (S91). An image is displayed on the liquid crystal panel (S93). Here, as shown in FIG. 5, a gamma curve 62 with an offset (solid line in the figure) is set as the gamma curve, the image signal is gamma corrected according to the gamma curve 62, and live view image display is performed on the TFT 33. Do.

  Note that the gamma curve 62 with offset is raised on the dark side (left side of the horizontal axis in the drawing) with respect to the gamma curve 61 without offset. In the example shown in FIG. 5, the offset value is simply added to the gamma curve 61, and the high input value side is a saturated curve. However, the present invention is not limited to this. For example, only the offset value is added on the dark side, and gradually added to the gamma curve while decreasing the offset value, or added to the gamma curve while increasing the offset value. Alternatively, a gamma curve with an offset may be determined so that the high input value side is saturated.

  When an image is displayed on the liquid crystal panel (TFT 33), the luminance of the backlight of the liquid crystal panel is then reduced (S95). The liquid crystal control unit 31 reduces the luminance of the backlight of the TFT 33 to reduce power consumption. This is because gamma correction is performed using a gamma curve with an offset, and a dark portion in the subject image becomes brighter, so that it can be sufficiently visually recognized even if the luminance of the backlight is lowered.

  Thus, in the flow of the live view operation, when the outside light is too bright and it is difficult to see the screen of the TFT 33 as it is, the gamma curve is changed to have an offset and gamma correction is performed. For this reason, since the dark part of the subject image is brightened as a whole, it can be sufficiently observed even when the surroundings are too bright. In this case, the bright part of the subject image is originally saturated and expressed in white, but there is no sense of incongruity because the surroundings are bright.

  If the backlight is reduced in step S95, or if an image is displayed on the liquid crystal panel in S97, the flow returns to the original flow.

  Next, the reproduction operation in step S23 will be described using the flowchart shown in FIG. In the flow of the reproduction operation, first, the selected image is read and image processing is performed (S101). In the reproducing operation, the image signal of the selected image is read from the recording medium 25 using the latest recorded image or the like as the selected image, the decompression process is performed by the compression / decompression unit 23, and the image process is performed by the image processing unit 15.

  Once image reading and image processing have been carried out, it is next determined whether or not there is an external light luminance of 100,000 lx or more in the external light sensor as in step S39 (S103). It is determined whether or not the external light brightness near the TFT 33 is too bright during reproduction.

  As a result of the determination in step S103, if the external light luminance is not 100,000 lx or more, an image is displayed on the liquid crystal panel using the normal set value gamma curve as in step S97 (S167). Here, the image signal read from the recording medium 25 is gamma-corrected according to the gamma curve 61 shown in FIG.

  On the other hand, if the result of determination in step S103 is that the ambient light luminance is 100,000 lx or more, the gamma curve is set with an offset (S161), and an image is displayed on the liquid crystal panel with the set gamma curve (S163). ). Since the external light luminance is 100,000 lx or more, the vicinity of the TFT 33 is too bright, and it is difficult to observe the screen of the TFT 33 as it is. Therefore, as in the case of live view display, the gamma curve has an offset to make the screen easier to see. That is, the gamma correction of the image signal is performed according to the gamma curve 62 with an offset as shown in FIG. Since the dark part of the subject image is brightened as a whole, it can be sufficiently observed even when the periphery of the TFT 33 is too bright.

  Once the reproduced image is displayed on the liquid crystal panel (TFT 33), the luminance of the backlight of the liquid crystal panel is then reduced (S165) as in step S95. The liquid crystal control unit 31 reduces the luminance of the backlight of the TFT 33 to reduce power consumption.

  If the backlight luminance is reduced in step S165 or if an image is displayed in step S167, it is next determined whether or not switching of the display image on the rear liquid crystal is instructed (S171). In this embodiment, since the switching of the reproduction image is performed by operating the cross key or the like, in this step, it is determined by determining whether or not the cross key or the like has been operated.

  If the result of determination in step S171 is that there has been a display image switching instruction, processing returns to step S101, and the selected image is read in accordance with the switching instruction. On the other hand, if the result of determination is that there has been no instruction to switch the display image, it is next determined whether or not an operation to end the playback mode has been performed (S173). In this embodiment, the end of the playback mode is performed again by operating the playback button. Therefore, this step is performed based on whether or not the playback button has been operated.

  If the result of determination in step S173 is that playback mode termination operation has not been performed, processing returns to step S101 and playback mode continues. On the other hand, if the playback mode end operation has been performed, the playback mode end processing is performed, and then the process returns to the original flow.

  As described above, in the flow of the reproduction operation, as in the case of the live view operation, when the external light is too bright and it is difficult to see the screen of the TFT 33 as it is, the gamma curve is changed to have an offset. Gamma correction is performed. For this reason, since the dark part of the subject image is brightened as a whole, it can be sufficiently observed even when the surroundings are too bright. In this case, the bright part of the subject image is originally saturated and expressed in white, but there is no sense of incongruity because the surroundings are bright.

  As described above, in the first embodiment of the present invention, a display image signal generated based on an image signal from an imaging unit or a recording medium, or a gamma curve with an offset with respect to this display image signal. A second display image signal that has been gamma-corrected using the generated signal is generated, and when the external light luminance is brighter than a predetermined value, an image based on the second display image signal is displayed, and the external light luminance is If it is darker than a predetermined value, an image based on the display image signal is displayed. For this reason, even when the surroundings are too bright, the visibility in the image display unit can be improved.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, when the external light luminance is high, the gamma curve is changed to have an offset, but in the second embodiment, in addition to the condition that the external light luminance is high, the image A histogram is obtained, and the gamma curve is changed to have an offset when there are many pixels whose luminance for each pixel is darker than a predetermined value.

  Since the configuration of the electric circuit in the present embodiment is the same as the block diagram shown in FIG. 1 in the first embodiment, detailed description thereof is omitted. The camera power-on operation is also the same as that shown in the flowchart of FIG. However, since the flowcharts of the live view operation and the reproduction operation are different from those in the first embodiment, differences will be mainly described.

  In the live view operation flow shown in FIG. 6, the processes in steps S31 to S39 and steps S91 to S97 are the same as the live view operation flow in the first embodiment shown in FIG. For this reason, the same step number is assigned to steps for performing the same processing, and detailed description thereof is omitted.

  The live view operation flow is entered, and the imaging operation (S31), AF operation (S33), photometry operation (S35), and image processing (S37) are performed. As a result of the determination in step S39, the external light sensor detects 100,000 lx. When the above is detected, a histogram of the liquid crystal panel display image is calculated (S41). Here, with respect to the display image signal generated based on the image signal acquired by the imaging sensor 9, a histogram is obtained based on the data for each pixel. In the histogram, as shown in FIG. 8, the horizontal axis indicates the pixel position, and the vertical axis indicates the signal output of each pixel, that is, the input gradation.

  Once the histogram is calculated, it is next determined whether or not there are 50% or more pixels in the image with gradation 135 or lower from the histogram (S43). In this embodiment, since the input gradation (signal output) of each pixel is 8 bits, the value of each pixel is between the maximum value 255 and the minimum value 0. Here, 135 in the middle is used as a reference, and it is determined whether the ratio of pixels darker than this determination value is 50% or more. Note that the gradations 135 and 50% are examples, and may be determined as appropriate in consideration of the characteristics of the TFT 33.

  If the result of determination in step S43 is that there are 50% or more pixels of gradation 135 or lower in the image, the gamma curve is set to have an offset (S91) as in the first embodiment, and the set gamma curve is set. Then, an image is displayed on the liquid crystal panel (S93), and the luminance of the backlight of the liquid crystal panel is reduced (S95). In step S39, it is determined that the external light luminance is high, and in step S43, it is determined that there are more than half of the pixels darker than the predetermined. Therefore, as in the first embodiment, the gamma curve has an offset. By changing the image signal and performing gamma correction on the image signal, the screen is easy to view even when the external light has high luminance.

  On the other hand, if the result of determination in step S39 is that the ambient light luminance does not exceed 100,000 lx, or the result of determination in step S43 is that there are no 50% or more pixels with gradation 135 or lower, the case of the first embodiment Similarly to the above, an image is displayed on the liquid crystal panel using the normal set value gamma curve (S97). In this case, even if the external light is not high-intensity, and even if it is high-intensity, there are few dark parts in the subject image as seen from the histogram of the display image. It will not be difficult to see.

  If the luminance of the backlight of the liquid crystal panel is reduced in step S95, or if an image is displayed in step S97, the original flow is restored.

  Next, the reproduction operation in the present embodiment will be described with reference to the flowchart shown in FIG. Of the flow of the reproduction operation shown in FIG. 7, the processes in steps S101 to S103 and steps S161 to S173 are the same as the flow of the reproduction operation in the first embodiment shown in FIG. 4. The steps for performing the same processing are given the same step numbers and will not be described in detail.

  A reproduction operation flow is entered, the selected image is read out, image processing is performed (S101), and it is determined whether or not 100,000 lx or more is detected by the external light sensor (S103). If the external light sensor detects 100,000 lx or more as a result of this determination, next, a histogram of the liquid crystal panel display image is calculated (S111). Here, for the display image signal generated based on the image signal read from the recording medium 25, a histogram is obtained based on the data for each pixel. In the histogram, as shown in FIG. 8, the horizontal axis indicates the pixel position, and the vertical axis indicates the signal output (input gradation) of each pixel.

  Once the histogram is calculated, next, as in step S43 (see FIG. 6), it is determined from the histogram whether or not there are 50% or more pixels of gradation 135 or less in the image (S113). In the present embodiment, as in the case of live view display, since the input gradation (signal output) of each pixel is 8 bits during playback display, the value of each pixel is the highest value 255 and the lowest value. It is determined whether or not the ratio of pixels that are in the middle between the values 0 and 135 in the middle is darker than this judgment value is 50% or more. Even in the reproducing operation, the gradations 135 and 50% are exemplifications, and may be determined as appropriate in consideration of the characteristics of the TFT 33.

  If the result of determination in step S113 is that there are no pixels of gradation 135 or lower in the image of 50% or more, or if the result of determination in step S103 is that the ambient light luminance is not 100,000 lx or more, the same as in step S97. Then, an image is displayed on the liquid crystal panel using the normal set value gamma curve (S167). Here, the image signal read from the recording medium 25 is gamma-corrected according to the gamma curve 61 shown in FIG.

  On the other hand, if the result of determination in step S113 is that there are more than 50% of pixels in the image with a gradation of 135 or less, the gamma curve is set with an offset (S161), and the image is displayed on the liquid crystal panel with the set gamma curve. Display is performed (S163). Since the brightness of outside light is 100,000 lx or more and the dark part of the reproduced image is more than half, the vicinity of the TFT 33 is too bright although the reproduced image is dark, and it is difficult to observe the screen of the TFT 33 as it is. As in the case of live view display, the gamma curve has an offset to make the screen easier to see.

  Once the reproduced image is displayed on the liquid crystal panel, the luminance of the backlight of the liquid crystal panel is then reduced as in step S95 (S165). The liquid crystal control unit 31 reduces the luminance of the backlight of the TFT 33 to reduce power consumption.

  If the backlight brightness is reduced in step S165 or if an image is displayed in step S167, it is next determined whether or not to switch the display image on the rear liquid crystal (S171). When the display image is switched, the process returns to step S101. On the other hand, if the display image is not switched, it is next determined whether or not a reproduction mode end operation has been performed (S173). As a result of the determination, if the end operation has not been performed, the process returns to step S101. On the other hand, if the end operation has been performed, the playback operation end process is performed, and the process returns to the original flow.

  As described above, in the second embodiment of the present invention, in the histogram of the luminance distribution of the pixel signal constituting the display image, when the number of pixels having a predetermined luminance or less exceeds a predetermined number, the lightness is determined to be a predetermined value or higher. . For this reason, accurate determination can be performed according to the luminance distribution of each pixel, and the visibility of the image display unit can be further improved at high luminance.

  Next, a third embodiment of the present invention will be described using FIG. 9 and FIG. In the second embodiment, in addition to the condition that the external light luminance is high, an image histogram is obtained, and the gamma curve is changed to have an offset when there are many pixels whose luminance is darker than a predetermined value for each pixel. I was trying to do it. On the other hand, in the third embodiment, in addition to the condition that the external light luminance is high, the average value of the histogram of the image is obtained, and when this average value is darker than the predetermined value, the gamma curve is offset. I am trying to change it.

  Since the configuration of the electric circuit in the present embodiment is the same as the block diagram shown in FIG. 1 in the first embodiment, detailed description thereof is omitted. The camera power-on operation is also the same as that shown in the flowchart of FIG. However, since the flowcharts of the live view operation and the reproduction operation are different from those of the first and second embodiments, differences will be mainly described.

  Of the flow of the live view operation shown in FIG. 9, the processes in steps S31 to S39 and steps S91 to S97 are the same as the flow of the live view operation in the first embodiment shown in FIG. For this reason, the same step number is assigned to steps for performing the same processing, and detailed description thereof is omitted.

  The live view operation flow is entered, and the imaging operation (S31), AF operation (S33), photometry operation (S35), and image processing (S37) are performed. As a result of the determination in step S39, the external light sensor detects 100,000 lx. If the above is detected, next, the histogram of a liquid crystal panel display image is calculated similarly to step S41 (refer FIG. 6) (S51). Here, the histogram is obtained in the same manner as the graph shown in FIG.

  Once the histogram is calculated, the average value of the input gradation is calculated from the histogram (S53). Here, the average value is calculated by dividing the total added value of the input gradations (signal output) of all the pixels in the target region by the total number of pixels.

  Once the average value of the input gradation is calculated, it is next determined whether or not the average value of the histogram is equal to or lower than the gradation 135 (S55). In this embodiment, since the input gradation (signal output) of each pixel is 8 bits, the value of each pixel is between the maximum value 255 and the minimum value 0. Here, 135 in the middle is used as a reference, and it is determined whether or not the average value of the histogram is smaller than this determination value. Note that the gradation 135 is an example, and may be appropriately determined in consideration of the characteristics of the TFT 33.

  As a result of the determination in step S55, if the average value of the histogram is equal to or lower than the gradation 135, the gamma curve is set with an offset (S91) as in the first and second embodiments, and the set gamma is set. The image is displayed on the liquid crystal panel at the curve (S93), and the luminance of the backlight of the liquid crystal panel is reduced (S95).

  On the other hand, if the result of determination in step S39 is that the ambient light luminance does not exceed 100,000 lx, or the result of determination in step S55 is that the average value is greater than the gradation 135, the first and second embodiments will As in the case, the image is displayed on the liquid crystal panel with the normal set value gamma curve (S97). In this case, even if the external light is not high-intensity, and even if it is high-intensity, there are few dark parts in the subject image as seen from the histogram of the display image. It will not be difficult to see.

  If the luminance of the backlight of the liquid crystal panel is reduced in step S95, or if an image is displayed in step S97, the original flow is restored.

  Next, the reproduction operation in the present embodiment will be described with reference to the flowchart shown in FIG. Of the flow of the reproduction operation shown in FIG. 10, the processes in steps S101 to S103 and steps S161 to S173 are the same as the flow of the reproduction operation in the first embodiment shown in FIG. The steps for performing the same processing are given the same step numbers and will not be described in detail.

  A reproduction operation flow is entered, the selected image is read out, image processing is performed (S101), and it is determined whether or not 100,000 lx or more has been detected by the external light sensor (S103). If the result of this determination is that the ambient light sensor detects 100,000 lx or more, next, as in step S111 (see FIG. 7), a histogram of the liquid crystal panel display image is calculated (S121).

  Once the histogram is calculated, next, the average value of the gradation is calculated from the histogram in the same manner as in step S53 (see FIG. 9) (S123). Once the average value of the histogram is obtained, next, as in step S55, it is determined whether or not the average value is equal to or lower than the gradation 135 (S125).

  As a result of the determination in step S125, if the average value of the histogram is larger than the gradation 135, or if the result of determination in step S103 is that the external light luminance is not 100,000 lx or more, the same as in step S97, An image is displayed on the liquid crystal panel using the set value gamma curve (S167). Here, the image signal read from the recording medium 25 is gamma-corrected according to the gamma curve 61 shown in FIG.

  On the other hand, if the result of determination in step S125 is that the average value of the histogram is less than or equal to gradation 135, the gamma curve is set with an offset (S161), and an image is displayed on the liquid crystal panel using the set gamma curve. (S163). In this case, the gamma curve has an offset to make the screen easier to see.

  When the reproduced image is displayed on the liquid crystal panel (TFT 33), next, the luminance of the backlight of the liquid crystal panel is reduced as in step S95 (S165). The liquid crystal control unit 31 reduces the luminance of the backlight of the TFT 33 to reduce power consumption.

  If the backlight brightness is reduced in step S165 or if an image is displayed in step S167, it is next determined whether or not to switch the display image on the rear liquid crystal (S171). If no switching is performed, the process returns to step S101. On the other hand, if the display image is switched as a result of the determination, it is next determined whether or not a reproduction mode end operation has been performed (S173). As a result of the determination, if the end operation has not been performed, the process returns to step S101. On the other hand, if the end operation has been performed, the playback operation end process is performed and the process returns to the original flow.

  As described above, in the third embodiment of the present invention, the average value of the gradation of the display image is obtained in the histogram of the luminance distribution of the pixel signal constituting the display image, and the average value is equal to or greater than the predetermined value. In some cases, the brightness is determined to be greater than a predetermined value. For this reason, accurate determination can be performed according to the average of the luminance distribution of each pixel, and the visibility of the image display unit can be further improved at high luminance.

  Next, a fourth embodiment of the present invention will be described using FIG. 11 and FIG. In the third embodiment, in addition to the condition that the external light luminance is high, the histogram of the image of the entire screen is obtained, and the gamma curve has an offset when the average value of gradation is darker than a predetermined value. I was going to change to. On the other hand, in the fourth embodiment, in addition to the condition that the external light luminance is high, a histogram of the area where the face is recognized is calculated, and pixels with gradation of 135 or less are imaged in this face recognition area. The gamma curve is offset when the image is darker than 50%.

  Since the configuration of the electric circuit in the present embodiment is the same as the block diagram shown in FIG. 1 in the first embodiment, detailed description thereof is omitted. The camera power-on operation is also the same as that shown in the flowchart of FIG. However, since the flowcharts of the live view operation and the reproduction operation are different from those in the first to third embodiments, differences will be mainly described.

  In the live view operation flow shown in FIG. 11, the processes in steps S31 to S39 and steps S91 to S97 are the same as the live view operation flow in the first embodiment shown in FIG. For this reason, the same step number is assigned to steps for performing the same processing, and detailed description thereof is omitted.

  In the live view operation flow, steps S31 to S39 are the same as the flowcharts shown in FIG. 3, FIG. 6, and FIG. If the result of determination in step S39 is that the ambient light sensor detects 100,000 lx or more, it is next determined whether or not there is face recognition (S61). Based on the image signal processed by the image processing unit 15, the face detection unit 17 detects whether a face exists in the subject image, and if a face exists, detects the position and size. Therefore, in this step 61, the determination is made based on the detection result by the face detection unit 17.

If the result of determination in step S61 is face recognition, a face recognition area histogram is then calculated (S63). Here, for the face recognition area, a histogram is calculated in the same manner as the histogram shown in FIG.

  Once the histogram is calculated for the face recognition area, it is next determined from the histogram whether or not there are 50% or more pixels of gradation 135 or less in the image (S65). Here, a pixel having a gradation of 135 or less is detected in the histogram in the face recognition area calculated in step S63, and it is determined whether this is 50% or more of the pixels in the face recognition area. The meaning of the gradation 135 is the same as that in step S113 in the second embodiment (the same applies to third to fifth embodiments described later). In the present embodiment, the gradations 135 and 50% are merely examples, and may be determined as appropriate according to the characteristics of the TFT 33.

  If the result of determination in step S65 is that there are no pixels of gradation 135 or lower in the image of 50% or more, or the result of determination in step S39 is that the external light sensor does not exceed 100,000 lx, the normal setting is made. An image is displayed on the liquid crystal panel using the value gamma curve (S97).

  On the other hand, if the result of determination in step S65 is that there are 50% or more of pixels with gradation 135 or lower, steps S91, S93, and S95 for performing gamma correction and the like with an offset gamma curve are executed. Since the processing in the steps is the same as the processing in FIGS. 3, 6, and 9, detailed description thereof is omitted. When the process in step S95 or S97 is performed, the process returns to the original flow.

  Next, the reproduction operation in the present embodiment will be described using the flowchart shown in FIG. In the flow of the reproduction operation, steps S101 to S103 are the same as the flowcharts shown in FIGS. 4, 7, and 10, and thus the description thereof is omitted. If the external light sensor detects 100,000 lx or more as a result of the determination in step S103, it is next determined whether or not there is face recognition (S131). In the shooting operation in step S17 (see FIG. 2), when the face recognition result is recorded together with the image signal recording, the recording result may be used. When such a face recognition result is not recorded, the face detection unit 17 may perform face recognition based on the image signal read from the recording medium 25.

  If the result of determination in step S131 is face recognition, a face recognition area histogram is then calculated (S133). Here, the histogram of the face recognition area is calculated in the same manner as in FIG. 8, using the image signal in the area determined as the face recognition area in step S131 among the image signals read from the recording medium 25. .

  When the histogram of the face recognition area is calculated, next, as in step S65 (see FIG. 11), it is determined whether or not pixels with gradation 135 or lower are 50% or more in the image of the face recognition area from the histogram. Is performed (S135). If the result of this determination is that there are 50% or more pixels of gradation 135 or lower in the area, steps S161 to S165 are executed. Since these processes are the same as the flowcharts shown in FIGS. 4, 7, and 10, the description thereof will be omitted.

  On the other hand, if the result of determination in step S135 is that there are no more than 50% of pixels in the area within the area, or if the result of determination in step S131 is that face recognition has not been performed, or the result of determination in step S103. If the ambient light sensor does not detect 100,000 lx or more, an image is displayed on the liquid crystal panel using the normal set value gamma curve (S167).

  If the backlight brightness is reduced in step S165, or if an image is displayed on the liquid crystal panel using the normal set value gamma curve in step S167, then the determination in steps S171 and S173 is performed. Since these determinations are the same as those in the flowcharts shown in FIGS. 4, 7, and 10, the description thereof is omitted. If the result of determination in step S173 is that there is a playback mode end operation, the playback operation processing ends and the flow returns to the original flow.

  As described above, in the fourth embodiment of the present invention, a predetermined number or less is a predetermined luminance or less in the histogram of the luminance distribution of the pixel signal constituting the face area detected by the face detection unit 17 in the display image. If it exceeds the predetermined value, it is determined that the brightness is equal to or greater than the predetermined brightness. In this case, the gamma curve is offset, and the gamma correction of the image signal is performed using the offset gamma curve. For this reason, an accurate determination can be performed on the face recognition area, and the visibility of the image display unit can be further improved at high luminance. In general, a person is often the main subject, and according to the present embodiment, it is easy to observe the face portion of the person.

  In the present embodiment, it is determined whether or not there are 50% or more of pixels with gradation 135 or lower in the face recognition area. However, the present invention is not limited to this, and it is of course possible to determine whether or not the average gradation of the face recognition area is equal to or less than a predetermined value (for example, gradation 135).

  Next, a fifth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, in addition to the condition that the external light luminance is high, a histogram of the face recognition area is obtained, and the gamma curve is offset when there are many pixels with gradations of 135 or less and there are 50% or more in darkness. I was going to change to. On the other hand, in the fifth embodiment, in addition to the condition that the external light luminance is high, a histogram of the focus area is calculated, and it is assumed that there are 50% or more of pixels with gradation 135 or less in the focus area. The gamma curve is offset when it is dark.

  Since the configuration of the electric circuit in the present embodiment is the same as the block diagram shown in FIG. 1 in the first embodiment, detailed description thereof is omitted. The camera power-on operation is also the same as that shown in the flowchart of FIG. However, since the flowcharts of the live view operation and the reproduction operation are different from those in the first to fourth embodiments, differences will be mainly described.

  Of the flow of the live view operation shown in FIG. 13, the processes in steps S31 to S39 and steps S91 to S97 are the same as the flow of the live view operation in the first embodiment shown in FIG. For this reason, the same step number is assigned to steps for performing the same processing, and detailed description thereof is omitted.

  When entering the flow of the live view operation, steps S31 to S39 are the same as the flowcharts shown in FIGS. 3, 6, 9, and 11, and the description thereof will be omitted. If the result of determination in step S39 is that the ambient light sensor detects 100,000 lx or more, then a focus area histogram is calculated (S71).

  As for the focus area, in a camera having only one focus area, a histogram is calculated based on the image signal of the focus area. In the case of a camera provided with a plurality of focus areas, in step S71, a histogram is calculated based on the image signal of the focus area adopted for focusing. Note that when there are a plurality of focus areas, the object used for focusing is, for example, the closest subject or the area where the face is recognized.

  Once the focus area histogram is calculated, it is next determined from the histogram whether or not there are 50% or more pixels in the image with gradation 135 or lower (S73). Here, it is determined using the histogram calculated in step S71 whether or not 50% or more of the pixels in the focus area have gradation 135 or lower in the image.

  If the result of determination in step S73 is that there are no pixels of gradation 135 or lower in the image of 50% or more, or the result of determination in step S39 is that there are not 100,000 lx or more in the ambient light sensor, the normal set value An image is displayed on the liquid crystal panel using the gamma curve (S97).

  On the other hand, if the result of determination in step S73 is that there are more than 50% of pixels in the image with a gradation of 135 or less, steps S91, S93, and S95 are executed. Since it is the same as the processing in FIG. 6, FIG. 9, and FIG. When the process in step S95 or S97 is performed, the process returns to the original flow.

  Next, the reproduction operation in this embodiment will be described using the flowchart shown in FIG. In the flow of the reproduction operation, steps S101 to S103 are the same as the flowcharts shown in FIGS. 4, 7, and 10, and thus the description thereof is omitted. If the result of determination in step S103 is that the ambient light sensor detects 100,000 lx or more, then a focus area histogram is calculated (S141).

  The focus area in step S141 is determined by recording information on the area in which the AF unit 3 has focused during the shooting operation in step S17 (see FIG. 2) together with the image signal and using the information at this time. . When the focus area is determined, a histogram is calculated using the image signal in this area, as in FIG.

  Once the focus area histogram has been calculated, it is next determined from the histogram whether or not there are 50% or more pixels in the image with gradation 135 or lower (S143). Here, it is determined using the histogram calculated in step S141 whether or not 50% or more of the pixels in the focus area have gradation 135 or lower in the image.

  If the result of determination in step S143 is that there are not 50% or more of the pixels with gradation 135 or lower in the image in the focus area, or as a result of determination in step S103, the ambient light sensor did not detect 100,000 lx or more. In this case, an image is displayed on the liquid crystal panel using the normal set value gamma curve (S167).

  On the other hand, if the result of determination in step S143 is that there are 50% or more of the pixels of gradation 135 or less in the image in the focus area, steps S161 to S165 are executed. Since these processes are the same as the flowcharts shown in FIGS. 4, 7, 10, and 12, description thereof will be omitted.

  If the backlight brightness is reduced in step S165, or if an image is displayed on the liquid crystal panel using the normal set value gamma curve in step S167, then the determination in steps S171 and S173 is performed. Since these determinations are the same as those in the flowcharts shown in FIGS. 4, 7, 10, and 12, description thereof will be omitted. If the result of determination in step S173 is that there is a playback mode end operation, the playback operation processing ends and the flow returns to the original flow.

  As described above, in the fifth embodiment of the present invention, the predetermined number or less is lower than the predetermined luminance in the histogram of the luminance distribution of the pixel signal constituting the focus area set by the AF unit 3 in the display image. If it exceeds, it is determined that the brightness is equal to or greater than the predetermined brightness. In this case, gamma correction of the image signal is performed using a gamma curve with an offset. For this reason, an accurate determination can be performed with respect to the focus area, and the visibility of the image display unit can be further improved at high luminance. In general, there are many cases where a main subject exists in an area set as a focus area, and according to the present embodiment, it becomes easy to observe a portion of the main subject.

  In the present embodiment, it is determined whether or not there are 50% or more of pixels with gradation 135 or lower in the focus area. However, the present invention is not limited to this, and it is of course possible to determine whether or not the average gradation of the focus area is a predetermined value (for example, gradation 135) or less.

  Next, a sixth embodiment of the present invention will be described with reference to FIGS. In the first to fifth embodiments, the example in which the TFT 33 is used as the display unit has been described. In contrast, the sixth embodiment is an example in which an organic EL (also referred to as an organic light-emitting diode or OLED (Organic light-emitting diode)) is used as the display unit.

  FIG. 15 is a block diagram showing an overall configuration mainly including the electrical system of the camera according to the present embodiment. Compared with the circuit configuration in the first embodiment shown in FIG. 1, the circuit configuration in the present embodiment includes the liquid crystal control units 27 and 29, the EVF 29, and the TFT 33 in the first embodiment. The present embodiment is different in that an organic EL control unit 51 and an organic EL 53 are provided. Therefore, these differences will be described in detail, and description of common elements will be omitted. In the block diagram of FIG. 15, the power supply battery 55 and the power supply control unit 57 are depicted, but these are also provided in the block diagram of FIG. 1, and are omitted for convenience. It is.

  The organic EL control unit 51 is connected to the buffer memory 19 and the recording medium 25, and the live view image and menu image image signal temporarily stored in the buffer memory 19 and the captured image read from the recording medium 25 are displayed. An image signal is input and control for displaying an image on the organic EL 53 is performed. Similar to the TFT 33, the organic EL 53 is disposed on the back surface of the camera or the like so that the user can directly observe the image without passing through the eyepiece. In this embodiment, an EVF is not provided, but an EVF using liquid crystal may be provided as in the first embodiment, or an EVF may be configured using an organic EL.

  The power battery 55 is a battery that can be loaded into the camera body, and is connected to the power controller 57. The power control unit 57 controls power supplied from the power battery 55 and supplies power to each element such as the organic EL control unit 51 and the organic EL 53 in the camera. The power control unit 57 is connected to the system controller 41 and performs power control according to instructions to the system controller 41. Further, the power supply control unit 57 can detect the amount of power consumption supplied to the organic EL 53 and the like.

  Next, the operation in this embodiment will be described with reference to the flowcharts shown in FIGS. Here, the camera power-on operation is the same as the flowchart of the first embodiment shown in FIG. Since the flowchart of the live view operation and the reproduction operation is different from that of the first embodiment, the difference will be mainly described.

  First, the live view operation will be described with reference to FIG. Since the first step S31 to step S37 are the same as those in the flowchart of the first embodiment shown in FIG. 3, detailed description will be omitted. Once image processing has been performed in step S37, image display is then performed on the organic EL panel using the normal set value gamma curve (S38). Here, first, a live view image is displayed on the organic EL 53. Here, as shown in FIG. 5, a gamma curve 61 without offset (broken line in the figure) is set as the gamma curve, the image signal is gamma-corrected according to the gamma curve 61, and live view image display is performed on the organic EL 53. I do. When live view display is performed on the organic EL 53, it is next determined whether or not 100,000 lx or more is detected by the external light sensor (S39).

  If the external light sensor detects 100,000 lx or more as a result of the determination in step S39, it is next determined whether or not the consumption current of the organic EL is equal to or less than a specified value (S81). In the second to fifth embodiments, the histogram of the display image is calculated, and based on this histogram, it is determined whether there are many dark portions in the subject image. In this embodiment, Without determining the histogram, it is determined whether there are many dark portions in the subject image based on the current consumption of the organic EL. The organic EL has many bright portions in the subject image, and the current consumption increases when the screen is bright. On the other hand, the current consumption decreases when the screen is dark and there are many dark portions in the subject image. Therefore, in the present embodiment, the power consumption control unit 57 detects the consumption current of the organic EL, and the brightness of the screen of the organic EL 53 is determined based on the detected consumption current. Therefore, the specified value may be appropriately determined as a design value in consideration of the characteristics of the organic EL 53.

  If the result of determination in step S81 is that the consumption current of the organic EL is less than or equal to the specified value, then the gamma curve is set with an offset (S91), and an image is displayed on the organic EL panel with the set gamma curve. Is displayed (S99). Here, as shown in FIG. 5, an offset gamma curve 62 (solid line in the figure) is set as the gamma curve, and the image signal is gamma-corrected according to the gamma curve 62 to display the live view image on the organic EL 53. Do.

  When an image is displayed on the organic EL panel in step S99, or if the result of determination in step S81 is that the consumption current of the organic EL is greater than a specified value, or the result of determination in step S39 is 100,000 lx by the external light sensor. If the above is not detected, the process returns to the original flow.

  Next, the reproducing operation will be described with reference to FIG. Since the first step S101 in the flow of the reproduction operation is the same as the flowchart of the first embodiment shown in FIG. 4, detailed description thereof is omitted. Once the selected image is read and processed in step S101, the image is then displayed on the organic EL panel using the normal set value gamma curve (S102). Here, similarly to step S38, a gamma curve 61 without offset is set, and the image signal of the captured image read from the recording medium 25 is gamma-corrected according to the gamma curve 61 and displayed on the organic EL 53 as a reproduced image. When an image is displayed on the organic EL panel, it is determined whether or not 100,000 lx or more is detected by the external light sensor (S103).

  As a result of the determination in step S103, if the ambient light sensor detects 100,000 lx or more, next, as in step S81, it is determined whether or not the consumption current of the organic EL is equal to or less than a specified value (S151). As described above, since the current consumption of the organic EL depends on the brightness of the screen, in this step, the power consumption control unit 57 detects the current consumption of the organic EL, and based on the detected current consumption, the organic EL The brightness of the EL53 screen is determined.

  If the result of determination in step S151 is that the consumption current of the organic EL is less than or equal to the specified value, then the gamma curve is set with an offset (S161), and an image is displayed on the organic EL panel with the set gamma curve. Is displayed (S163). Here, as shown in FIG. 5, an offset gamma curve 62 (solid line in the figure) is set as the gamma curve, the image signal is gamma-corrected according to the gamma curve 62, and the reproduced image is displayed on the organic EL 53. .

  In step S164, when an image is displayed on the organic EL panel, or if the result of determination in step S151 is that the consumption current of the organic EL is greater than a specified value, or the result of determination in step S103 is 100,000 lx at the external light sensor. If the above is not detected, it is next determined whether or not switching of the display image of the rear organic EL has been instructed (S172). Since the reproduction image is switched by operating the cross key or the like in this embodiment as well, in this step, it is determined by determining whether or not the cross key or the like has been operated.

  If the result of determination in step S172 is that there has been a display image switching instruction, processing returns to step S101. On the other hand, if the result of determination is that there has been no instruction to switch the display image, it is next determined whether or not an operation to end the playback mode has been performed (S173). Since the end of the playback mode is performed again by operating the playback button in this embodiment, this step is performed based on whether or not the playback button has been operated. On the other hand, if the result of this determination is that there has been a playback mode end operation, the flow returns to the original flow.

  As described above, in the sixth embodiment, an organic EL is employed as a display unit for displaying a live view image or a reproduced image, and when the consumption current of the organic EL is less than a specified value, the gamma curve is offset, Gamma correction is performed. For this reason, also in this embodiment, even when the surroundings are too bright, the visibility in the image display unit can be improved. In the present embodiment, the brightness of the screen can be detected by detecting the current consumption of the organic EL without calculating the histogram, so that the processing is easy.

  In the present embodiment, the EVF 29 is omitted. Of course, the EVF 29 may be provided together with the organic EL 53 so that an image can be observed through the viewfinder.

  As described above, in each embodiment of the present invention, the brightness of external light is detected to determine whether the external light brightness is equal to or higher than the predetermined brightness, and the external light brightness is determined to be equal to or higher than the predetermined brightness. Is configured to generate and display a second display image by offsetting the gamma curve with respect to the display image signal. For this reason, it becomes possible to improve the visibility of the image display unit at high luminance.

  In each embodiment of the present invention, gamma correction is performed on the TFT 33 and the organic EL 53 using a gamma curve with an offset when the external light luminance is high. However, the present invention is not limited to this, and gamma correction may be similarly performed on the EVF 29. Thereby, the gamma correction in the image processing unit 15 can be made common, and the image processing is simplified.

  Further, in each embodiment of the present invention, an example in which the present invention is applied to a camera having both a photographing function and a display function has been described. However, the present invention is not limited to this, and it is needless to say that the present invention may be applied to an image display apparatus that does not have a photographing function and has only a display function.

  In each embodiment of the present invention, a digital camera has been described as an apparatus for photographing. However, the camera may be a digital single lens reflex camera or a compact digital camera, such as a video camera or a movie camera. It may be a camera for moving images, or may be a camera built in a mobile phone, a personal digital assistant (PDA), a game device, or the like.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, you may delete some components of all the components shown by embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 ... Shooting lens, 3 ... AF part, 5 ... Aperture, 7 ... Shutter, 9 ... Imaging sensor, 11 ... Imaging circuit, 13 ... A / D conversion, 15 ... Image processing unit, 17 ... Face detection unit, 19 ... Buffer memory, 21 ... Menu image recording unit, 23 ... Compression / decompression unit, 25 ... Recording medium, 27 ... Liquid crystal control unit, 29 ... EVF, 31 ... Liquid crystal control unit, 33 ... TFT, 35 ... External light sensor, 37 ... Operating unit, 41 ... System controller, 51 ... Organic EL control unit 53 ... Organic EL, 55 ... Power supply battery, 57 ... Power supply control unit, 61 ... Gamma curve, 62 ... Gamma curve

Claims (16)

In an imaging device that images a subject and generates an image signal,
An imaging unit that receives a subject light and repeatedly generates a display image signal and receives a shooting instruction to generate a recording image signal;
An external light luminance determination unit that detects the luminance of external light and determines whether the external light luminance is equal to or higher than a predetermined luminance;
A display control unit that generates a second display image signal using a gamma curve with respect to the display image signal generated by the imaging unit;
A display unit for displaying a live view image based on the second display image signal output from the display control unit;
Have
The display control unit offsets the gamma curve from the display image signal generated by the imaging unit when the external light luminance determination unit determines that the external light luminance is equal to or higher than the predetermined luminance. An image pickup apparatus that generates two display images. An image brightness determination unit for determining whether the display image has a predetermined brightness or more based on the display image signal;
In the case where the external light luminance determined by the external light luminance determination unit is determined to be equal to or higher than the predetermined luminance and the display image is determined to be equal to or higher than the predetermined luminance by the image lightness determination unit, the display control unit The imaging apparatus according to claim 1, wherein the second display image is created by offsetting the gamma curve with respect to the generated display image signal.   The image brightness determination unit determines that the brightness is equal to or higher than a predetermined brightness when a predetermined brightness or lower exceeds a predetermined number in a histogram of brightness distribution of pixel signals constituting the display image. Imaging device.   The image brightness determination unit determines that the average value of the luminance distribution of pixel signals constituting the display image is equal to or higher than a predetermined brightness when the average value is equal to or lower than a predetermined luminance. Imaging device. A face detection unit for detecting a face from an image signal output by the imaging unit and determining a face region;
The image brightness determination unit determines that the brightness is equal to or greater than a predetermined brightness when a predetermined luminance or less exceeds a predetermined number in a histogram of luminance distribution of pixel signals constituting the face area detected by the face detection unit in the display image. The imaging apparatus according to claim 2, wherein the determination is performed. An AF unit for setting a focus area based on an image signal output from the imaging unit and performing an AF operation;
The image brightness determination unit determines that the brightness is equal to or greater than a predetermined brightness when a predetermined brightness or less exceeds a predetermined number in a histogram of the brightness distribution of pixel signals constituting the focus area set by the AF section in the display image. The imaging apparatus according to claim 2, wherein: The display unit has a backlight unit,
When the control unit creates the second display image by offsetting the gamma curve with respect to the display image signal generated by the imaging unit, the display control unit supplies power to the backlight unit. The imaging device according to claim 1, wherein the imaging device is reduced. In an imaging device that images a subject and generates an image signal,
An imaging unit that receives a subject light and repeatedly generates a display image signal and receives a shooting instruction to generate a recording image signal;
A display control unit that creates a second display image signal using a gamma curve for the display image signal generated by the imaging unit;
A display unit for displaying a live view image based on the second display image signal output from the display control unit;
Have
The display control unit offsets the gamma curve with respect to the display image signal generated by the imaging unit and determines the second display image when the current consumption of the display unit is determined to be a predetermined value or more. An imaging apparatus characterized by creating an image. In an image reproducing apparatus for reproducing and displaying a recorded image signal,
A recording unit for recording the image signal;
An external light luminance determination unit that detects the luminance of external light and determines whether the external light luminance is equal to or higher than a predetermined luminance;
A display control unit that creates a second display image signal using a gamma curve for the display image signal output from the recording unit;
A display unit for displaying a reproduced image based on the second display image signal output from the display control unit;
With
When the external light luminance determination unit determines that the external light luminance is equal to or higher than the predetermined luminance, the display control unit offsets the gamma curve from the display image signal output from the recording unit, An image reproducing apparatus for generating a display image. An image brightness determination unit for determining whether the display image has a predetermined brightness or more based on the display image signal;
When the external light luminance determination unit determines that the external light luminance is equal to or higher than the predetermined luminance and the image lightness determination unit determines that the display image is equal to or higher than the predetermined lightness, the display control unit 10. The image reproduction apparatus according to claim 9, wherein the second display image is created by offsetting the gamma curve with respect to the output display image signal.   The image brightness determination unit determines that the brightness is equal to or higher than a predetermined brightness when a predetermined brightness or less exceeds a predetermined number in a histogram of brightness distribution of pixel signals constituting the display image. Image playback device.   11. The image according to claim 10, wherein the image brightness determination unit determines that the brightness is equal to or higher than a predetermined brightness when an average value of brightness distributions of pixel signals constituting the display image is equal to or lower than a predetermined brightness. Playback device. A face determination recording unit that determines that a face is detected and a face area is determined at the time of shooting based on an image signal output from the recording unit;
The image brightness determination unit is equal to or higher than a predetermined brightness when a predetermined luminance or less exceeds a predetermined number in a histogram of luminance distribution of pixel signals constituting the face area determined by the face determination recording unit in the display image. The image reproduction device according to claim 10, wherein the image reproduction device is determined. A focus area recording unit that determines a focus area set at the time of shooting based on an image signal output from the recording unit;
The image brightness determination unit determines that the brightness is equal to or higher than a predetermined brightness when a predetermined luminance or less exceeds a predetermined number in a histogram of luminance distribution of pixel signals constituting the focus area determined by the focus recording unit in the display image. The image reproduction apparatus according to claim 10, wherein the determination is made. The display unit has a backlight unit,
When the control unit creates the second display image by offsetting the gamma curve with respect to the display image signal output from the recording unit, the display control unit supplies the backlight unit with the display image signal. The image reproducing apparatus according to claim 9, wherein power is reduced. In an image reproducing apparatus for reproducing and displaying a recorded image signal,
A recording unit for recording the image signal;
A display control unit that creates a second display image signal using a gamma curve for the display image signal output from the recording unit;
A display unit for displaying a reproduced image based on the second display image signal output from the display control unit;
Have
The display control unit offsets the gamma curve with respect to the display image signal output by the recording unit when the current consumption of the display unit is determined to be equal to or greater than a predetermined value. An image reproduction apparatus characterized by creating