JP2000115627A - Digital camera having exposure meter function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital camera capable of executing photometry similar to a single exposure meter and being substituted for the exposure meter. SOLUTION: This digital camera is provided with an image pickup sensor 6, a first arithmetic means 20d for computing the luminance of an object based on image data obtained through the image pickup sensor and an input means 14 capable of inputting the data of at least one of exposure time, a stop value and film sensitivity. Based on the object luminance computed by the first arithmetic means and the data inputted by the input means, a second arithmetic means 20e computes an appropriate exposure conditions. The result is displayed at a display means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera, and more particularly, to a digital camera having an exposure meter function.

[0002]

2. Description of the Related Art Digital cameras have low resolution and low gradation, and are often inferior in image quality to silver halide photographs using silver halide films. Therefore, a digital camera is often used in combination with a silver halide camera, and for checking a subject or the like when photographing with the silver halide camera.

[0003]

When taking a photograph with a silver halide single-lens reflex camera or the like, photometry may be performed using a single exposure meter in order to obtain a more appropriate exposure. In such a case, in addition to the silver halide single-lens reflex camera and the digital camera, it is necessary to bring an exposure meter and go to the shooting site, which has resulted in an increase in shooting equipment and weight.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a digital camera which can perform photometry similar to a single exposure meter and can be used as an exposure meter.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been made with a focus on the fact that a digital camera has an image pickup circuit therein, so that photometry of a subject is possible. is there.

That is, an object of the present invention is to provide an image sensor, first calculating means for calculating the brightness of a subject based on image data obtained through the image sensor, exposure time, aperture value, and film sensitivity. Second means for calculating an appropriate exposure condition based on input means capable of inputting at least one of the data, subject brightness calculated by the first calculating means, and data input by the input means. A digital camera having an exposure meter function, comprising: a calculating unit; and a display unit for displaying the exposure condition calculated by the second calculating unit.

According to this digital camera, first, the brightness of the subject is calculated by the first calculating means based on the image data obtained through the image sensor, and the calculated brightness is input by the input means. From the data of at least one of exposure time, aperture value, and film sensitivity, an appropriate exposure condition is calculated by the second calculating means.

As is well known, subject brightness (hereinafter referred to as BV value), exposure time or shutter speed (hereinafter referred to as TV value) as parameters for obtaining proper exposure,
Aperture value (hereinafter referred to as AV value), film sensitivity (hereinafter referred to as AV value)
SV value), EV value (Exposure Value)
There is a relationship EV = BV + SV = AV + TV between e). By input means, for example, SV value and TV
When a value is input, the second calculating means calculates an AV value or an EV value for obtaining a proper exposure from the above equation.

Then, the result is displayed on the display means.

In the case where there is provided image processing means for performing image processing on the image data under the exposure conditions, and display means for displaying the image-processed image data, pseudo processing is performed under the set exposure conditions. The displayed image is displayed on the display unit, so that the image image can be confirmed.

[0011]

FIG. 1 is a block diagram showing a main configuration of a digital camera according to an embodiment of the present invention.
FIG. 2 is a rear view of the digital camera.

The digital camera 1 has a photographic lens 3 mounted on the front of a camera body 2, and the photographic lens 3 is provided with a photographic lens unit 4.

An aperture 5 is disposed behind the taking lens unit 4 in the optical path direction, and C
An image sensor 6 made of a CD is arranged. Note that 7
Is an eyepiece.

On the back of the camera body 2, there is provided a display section 8 comprising a liquid crystal display for displaying an image obtained based on the output of the image sensor 6, and the display section 8 has a preview before photographing. Images, captured images, and reproduced images are displayed. In the light meter mode, the display unit 8 displays the calculated exposure condition, and further displays a simulation image when it is assumed that the image was captured under the exposure condition.

Further, a memory card 72 as a storage medium for storing image data is removably mounted on the camera body 2. A shutter button 10 is provided on the upper surface of the camera body 2.

Further, on the right side of the rear surface of the camera body 2, a "camera photographing mode" in which the digital camera 1 performs normal photographing, a "exposure meter mode" in which the digital camera 1 functions as an exposure meter, and a "camera reproducing" for reproducing photographed images. A mode setting slide switch serving also as a power switch for setting the mode to any one of the “mode” and the “power off mode” is provided. Two switches 1 are provided above the mode setting switch 11 for frame-forwarding the recorded image in the direction in which the frame number increases (in the order of photographing) and in the direction in which the frame number decreases.
2 and 13 are provided.

On the left side of the display unit 8, an ISO / TIME key 14 operated in the exposure meter mode is provided. This ISO / TIME key 14 is used to set the SV value, T
When the V value is input, the setting is switched. Each time the key is pressed, the film sensitivity and the exposure time are alternately switched. In each setting, by operating two select switches 15 and 16 provided below the key, the ISO value as the SV value or the T value as the TV value is operated.
The IME value is sent from a small value to a large value or vice versa.

Further, the select switches 15, 16
An EV / Fno key 17 is provided below the lens, and the F value (F / F) of the lens as the calculated EV value or AV value is provided.
No) can be selectively switched and displayed.

Below the display section 8, a photometric range for the image data is set for the entire image (hereinafter referred to as average photometry) or in a spot area at the center of the image (hereinafter referred to as spot photometry). A photometric range changeover switch 18 for changing the setting is provided, and an ENTER key 19 for determining a setting condition or an input value is provided beside the switch 18.

In FIG. 1, reference numeral 20 denotes a camera control CPU, which controls each part of the camera body 2. Specifically, the camera control C based on the light amount data measured by the image sensor 6
The PU 20 calculates the exposure control data, controls the optical stop 5 via the stop driver 21 based on the calculated data, and controls the optical stop 5 via the timing generator 22 so that the exposure amount of the image sensor 6 becomes appropriate. The charge accumulation time (exposure time) is controlled.

A camera operation switch 23 is connected to the camera control CPU 20. The camera operation switch 23 includes the shutter button 10, the mode setting switch 11, the ISO / TIME key 14, the EV / Fno key 17, the light metering range switch 18, and the ENTER key 1.
9 and so on.

Further, in the exposure meter mode, the camera control CPU 20 also functions as a calculation means for calculating a BV value and calculating an appropriate exposure condition. This will be described later.

The image sensor 6 includes R (red), G
An all-pixel readout type area sensor in which primary color transmission filters (green) and B (blue) are arranged in a checkered pattern in pixel units, and optical images of a subject taken in from the imaging lens 3 are R, G, and B The image signal is photoelectrically converted into an image signal of a color component (a signal composed of a signal sequence of pixel signals received by each pixel) and output.

The timing generator 22 generates and outputs a drive control signal for the image sensor 13 based on a reference clock transmitted from the camera control CPU 20. The timing generator 22 generates clock signals such as integration start / end (exposure start / end) timing signals, readout control signals (horizontal synchronizing signal, vertical synchronizing signal, transfer signal, etc.) of the light receiving signal of each pixel, and the like. Output to the image sensor 13 via the driver.

The output of the image sensor 6 is subjected to signal processing by a CDS (correlated double sampling) circuit 61, an AGC (auto gain control) circuit 62, and an A / D converter 63. The CDS circuit 61 reduces the noise of the image signal, and the AGC circuit 62 adjusts the level of the image signal by adjusting the gain. The A / D converter 63 is an AGC circuit 6
It converts the analog signal normalized by 2 into a 10-bit digital signal.

An image processing unit 40 performs image processing on the output of the A / D converter 133 to form an image file.
It is controlled by the image processing CPU.

The signal from the A / D converter 63 taken into the image processing unit 40 is written into the image memory 71 in synchronization with the reading from the image sensor 6, and thereafter, the data in the image memory 71 is accessed. Processing of each block is performed.

In the image processing section 40, the average value calculation block 41 is used for the entire area of the image data in the photographing mode, and in the exposure meter mode, according to the above-mentioned average photometry or spot photometry. The average value of each area is calculated for each.

The pixel interpolation block 42 is a block for performing pixel interpolation with a predetermined interpolation pattern. In this embodiment, each pixel of R, G, and B is masked by a respective filter pattern and then has pixels up to a high band. For G, the median (intermediate value) filter uses the middle 2 of the surrounding 4 pixels.
Replace with the average of the values and average interpolate for R and B,
Get each output.

The color balance control block 43 determines the values of R and R for which pixel interpolation has been performed by the pixel interpolation block 42.
The G and B outputs are independently subjected to gain correction to perform R, G, and B color correction. About color balance,
Camera control C for the average of each of the R, G, and B outputs
R / G and B / G are calculated by the PU 20 to obtain R and B correction gains.

The gamma correction block 44 performs non-linear conversion on each of the R, G, and B outputs whose color balance has been normalized, and performs gradation conversion suitable for the display unit 8. The gamma-corrected image data is stored in the image memory 71.

The video encoder 45 includes the image memory 7
1 is called and the NTSC / PA
Encoded to L and displayed on the display unit 8. At the time of the preview, the image is updated at a predetermined frame cycle and is displayed on the display unit 8 at a moving image rate. On the other hand, after photographing, the photographed image is displayed on the display unit 8, and after a predetermined time, the image returns to the preview state again.

The image compression block 46 performs a compression process by retrieving image data from the image memory 71 with respect to the captured image obtained from the image sensor 6, and the captured image is stored in the memory via the memory card driver 47 after being compressed. It is recorded on the card 72.

The simulation processing block 48 performs simulated image processing on image data photographed by a digital camera and stored in an image memory under the exposure conditions calculated in the exposure meter mode. The image-processed data is supplied to the video encoder 45.
Is displayed on the display unit together with the exposure conditions.

FIG. 3 is a block diagram when the digital camera 1 functions as an exposure meter. In FIG. 3, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The camera control CPU 20 includes a Y matrix operation unit 20a, an SS (shutter speed) value operation / aperture value operation unit 20b, a camera sensitivity storage unit 20c, a BV
It comprises a value calculation unit 20d and a photometric value calculation unit 20e.

The Y matrix operation section 20a converts each of the RGB average values calculated by the average value calculation block 41 into a luminance signal (Y signal). Then, based on the calculation result, the SS value calculation / aperture value calculation unit 20b calculates an appropriate AV value and TV value, and the exposure time and the aperture of the image sensor 6 are feedback-controlled based on the calculated AV value and TV value. A diaphragm encoder 5a is incorporated in the diaphragm spring,
An accurate AV value in an actual operating state can be obtained.

The BV value calculator 20d calculates the SS value.
The TV value calculated by the aperture value calculation unit 20b, the AV value obtained by the aperture encoder 5a, and the camera sensitivity storage unit 20
The BV value is calculated from the inherent camera sensitivity (SV value) corresponding to the film sensitivity stored in advance in c.

Since there is a relationship of EV = BV + SV = AV + TV (1) among the BV value, TV value, AV value, SV value and EV value, the BV value can be obtained. It should be noted that the BV value calculator 20d is provided with a Y matrix calculator 20a.
(Appropriate exposure determination signal) is received, and based on this signal, it is also determined whether or not the imaging system at the time of photometry is in an appropriate operation range.

The photometric value calculation section 20e is provided with an ISO / TIME
The SV value (ISO sensitivity) and the TV value set and input in advance through the key 14 and the BV obtained by the BV value calculation unit 20d
Based on the values, the EV value and the AV value are calculated from the above equation (1).

FIG. 4 shows the state of the display unit 8 in each mode when the digital camera 1 is set to a desired mode by operating the mode setting switch 11.

FIG. 4A shows a display in the exposure meter mode, and the calculated AV value (F value) or EV is displayed on the display unit 8.
The value, the set SV value, the set TV value, and the analog F value are displayed. Also, a simulation image subjected to image processing under these exposure conditions is displayed.

FIG. 4B shows a display in the photographing mode.
A preview image or a captured image is displayed.

FIG. 4C shows a display in the reproduction mode.
The image called from the memory card 72 is a frame number,
It is displayed along with the shooting date.

Next, the operation of the digital camera 1 shown in FIGS. 1 to 3 will be described.

<Shooting Mode, Reproduction Mode> Shooting Lens 3
The optical image incident from the lens unit 4 is formed on the image sensor 6. The imaging sensor 6 photoelectrically converts the optical image and outputs an analog image signal. This image signal corresponds to the above-mentioned C
The signal is processed by the DS 61, the AGC 62, and the A / D converter 63, and is subjected to predetermined image processing by a pixel interpolation block 42, a color balance control block 43, and a gamma correction block 44. Is displayed. This operation is repeated at a predetermined frame cycle.

When the shutter button 10 is half-pressed,
For the image data at that time, the average value calculation block 4
At 1, an average value is calculated for each of R, G, and B. Each of the calculated RGB average values is converted into a luminance signal (Y signal) by the Y matrix operation unit 20a,
The value is input to the value calculation / aperture value calculation unit 20b, and the calculation unit calculates an appropriate AV value and TV value. Based on this, the exposure time and the aperture of the image sensor 6 are feedback-controlled via the timing generator 22 and the aperture driver 21, respectively.

When the shutter button 10 is fully pressed,
The optical image is captured by the image sensor 6 with the set exposure time and aperture. The image data from the image sensor 6 is signal-processed by the CDS 61, the AGC 62, and the A / D converter 63, and then written to the image memory 71.
Pixel interpolation block 42, color balance control block 4
3. After being subjected to predetermined processing in the gamma correction block 44 and stored in the image memory 71 again, it is called from the image memory 71 and displayed on the display unit 8 as a photographed image via the video encoder 45. At the same time, the image is compressed by the image compression block 46 and then recorded on the memory card 72 via the memory card driver 47.

In the playback mode, the memory card 7
The captured image recorded in 2 is displayed on the display unit 8 via the video encoder 45.

<Exposure Meter Mode> In the exposure meter mode, first, the ISO / TIME key 14 and the select switch 15,
The user sets the intended SV value and TV value in the silver halide photograph by using the button 16 and inputs them by pressing the ENTER key 19. The measurement range changeover switch 18 selects whether to use average photometry or spot photometry.

The display section 8 displays a preview image as in the case of the above-described shooting mode.

When the shutter button 10 is half-pressed,
For the image data at that time, the average value calculation block 4
At 1, an average value is calculated for each of R, G, and B. The calculation of the average value is performed in a predetermined range according to the average photometry or the spot photometry. Each of the calculated average values of RGB is converted into a luminance signal (Y signal) by a Y matrix calculation unit 20a, and then input to an SS value calculation / aperture value calculation unit 20b. And the TV value are calculated. Based on this, the exposure time and the aperture of the image sensor 6 are feedback-controlled via the timing generator 22 and the aperture driver 21, respectively.

When the shutter button 10 is fully pressed,
The optical image is captured by the image sensor 6 with the set exposure time and aperture. On the other hand, the TV value is also input to the BV value calculation unit 20d and the aperture value encoder 5
The accurate AV value according to a is input to the BV value calculation unit 20d.

The BV value calculator 20d calculates the TV value and the AV
The SV value stored in the camera sensitivity storage unit 20c is added to the value to calculate a BV value. The BV value calculation unit 20d calculates Y
From the output of the matrix operation unit 20a, it is determined whether or not the imaging system at the time of photometry is within a proper operation range. If the imaging system is within the proper operation range, the obtained BV value is output to the photometry value calculation unit 20e. If not within the range, an error is output to the photometric value calculation unit 20e.

The photometric value calculator 20e is provided with a BV value calculator 20.
The BV value calculated by d, the SV value input in advance, and the TV
Using the values, the EV value and the AV value are calculated from the above equation (1). Then, these EV value and AV value are displayed on the display unit 8 via the video encoder 45 and according to the setting mode of the EV / Fno key 17. When an error is output from the BV value calculation unit 20d, the fact is displayed on the display unit 8.

At the same time, the output of the photometric value calculation section 20e is also input to the simulation processing block 48. The simulation processing block 48 calls up the captured image data stored in the image memory 71, reprocesses the image under the set exposure condition, and displays the image on the display unit 8 via the video encoder 45. Thereby, the user can confirm the image at the time of taking the silver halide photograph. In the case of an error, it is preferable to display an incorrect image corresponding to the error in order to facilitate recognition of the error.

FIG. 5 shows various display states of the display section 8 in the exposure meter mode.

FIG. 9A shows a state in which the F value display is selected by the EV / Fno key 17 and the average photometry is selected by the measurement range switch 18, and the F value is displayed together with the set SV value and TV value. It is displayed, and the F value in analog is also displayed.

FIG. 5B shows a state in which the F value display is selected by the EV / Fno key 17 and the spot metering is selected by the measurement range changeover switch 18. In addition to the display of FIG. A photometry area is shown in the center of the image.

FIG. 5 (c) shows the EV / Fno key 17
This is the state when the value display is selected and the average photometry is selected with the measurement range changeover switch 18, and the EV value is displayed instead of the F value in the display of FIG.

FIG. 5D shows a display state when proper photometry is not performed, and the character "ERROR" is displayed instead of the F value shown in FIG. 5A.

In the above embodiment, the SV value and the TV value are input in order to obtain a proper exposure condition.
What is necessary is just to input at least one of a value, a TV value, and an AV value. For example, by inputting an SV value, a combination of a TV value and an AV value for achieving proper exposure may be displayed.

Although the aperture 5 of the digital camera 1 is made variable to calculate the BV value, the aperture may be fixed and only the exposure time of the image sensor 6 may be variably controlled.

The simulation processing block 48
According to the above, the image is pseudo-processed under the calculated exposure condition and is displayed on the display unit 8. However, the image obtained by the digital camera may be displayed without the pseudo process, or the image may be displayed. It does not have to be displayed.

Although the display unit for displaying the calculated exposure condition is also used as the display unit 8 for displaying the digital camera image, a dedicated display unit for displaying the exposure condition may be provided.

[0066]

As described above, according to the present invention, the brightness of the subject is calculated based on the image data obtained through the image sensor, and the calculated brightness, the input exposure time, and the aperture value are calculated. Value, and at least one of the film sensitivity data, the appropriate exposure condition is calculated and displayed, so it has the same function as a single exposure meter and can be used as a high value digital camera. I can do it.
For this reason, even when photometry is performed using a light meter at the time of shooting with a silver halide camera, it is sufficient to bring only a digital camera, which can contribute to reduction of shooting equipment.

When an image processing means for processing image data under the set exposure condition and a display means for displaying the image processed image data are provided, the image data is processed under the set exposure condition. The displayed image is displayed on the display unit, so that the image can be confirmed, and more reliable silver halide photography can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a main configuration of a digital camera according to an embodiment of the present invention.

FIG. 2 is a rear view of the digital camera.

FIG. 3 is a block diagram illustrating an exposure calculation function of the digital camera in FIG. 1;

FIG. 4 is a rear view showing a display state of a display unit in each mode of the digital camera in FIG. 1;

FIG. 5 is a rear view showing each display state of the digital camera in FIG. 1 in a light meter mode.

[Explanation of symbols]

1 Digital camera 2 Camera body 3 Photography lens 5 Aperture 6 Aperture 6 ··· Image sensor 8 ············· Display unit (display means) 11 ····· Mode setting switch 14 ····· ISO / TIME key (input means) 17 ··· ... EV / Fno key 18... Metering range switch 20... Camera control CPU 20d... BV value calculation unit (first calculation means) 20e ... Photometric value calculation section (second calculation means) 40... Image processing section 41... Average value calculation block 48... Simulation processing Block (image processing means)

Continued on the front page F term (reference) 2H002 AB01 CC01 CC21 DB01 DB06 DB19 DB23 EB00 FB02 FB23 FB24 FB25 FB30 FB51 FB52 FB53 FB57 FB71 GA00 GA33 GA68 JA07 5C022 AA00 AA11 AB04 AB06 AB17 AC03 AC13 AC32 AC33 AC42 AC69

Claims (2)

[Claims] 1. An image sensor based on image data obtained through the image sensor.
First calculating means for calculating the brightness of the subject, input means capable of inputting at least one of data of exposure time, aperture value, and film sensitivity; subject brightness calculated by the first calculating means;
Based on the data input by the input means,
A digital camera having a light meter function, comprising: second calculating means for calculating an appropriate exposure condition; and display means for displaying the exposure condition calculated by the second calculating means. 2. The digital camera having an exposure meter function according to claim 1, further comprising: an image processing unit for performing image processing on the image data under the exposure condition; and a display unit for displaying the image processed image data. .