JPH01221994A - Electronic still camera - Google Patents

Abstract

PURPOSE:To certainly obtain well corrected pictures by performing picture recording plural times by changing a detected color temperature in steps when the photographing mode, in which the white balance is continuously changed, is selected. CONSTITUTION:In case the white balance continuously changing photographing mode is selected, correct signals which change the amplification factors GB and GR of a process amplifier 22 in steps are outputted from a microcomputer 27 in addition to the automatic adjustment of the white balance at the color temperature detected by means of a color temperature sensor and color-corrected picture recording is performed plural times. Therefore, the picture recording with a properly adjusted white balance is included in the plural times of picture recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic still camera incorporating a white balance adjustment device. It is something.

[Conventional technology]

Generally, electronic still cameras have a built-in automatic mill balance adjustment device. This automatic white balance adjustment device uses a color temperature sensor that detects the color temperature of the light source illuminating the subject, and a color correction that corrects the primary color signal output from the image sensor according to the detected color temperature. It consists of a circuit.

According to such an automatic white balance adjustment device, even if a subject is illuminated by a light source with uneven color temperature, such as a fluorescent lamp, a color-corrected video signal will be recorded on the still video floppy. As a result, images with natural color balance can be obtained during image playback.

Automatic white balance adjustment devices are broadly classified into TTL type and external light type depending on the light receiving method of the color temperature sensor. TT
With the L method, the light itself from the shooting screen is used as the input light for color temperature detection, so the white balance can be adjusted to follow the shooting angle of view without being affected by light sources outside the shooting screen. Also, good adjustment function can be obtained even under backlight conditions. However, this TTL method detects color temperature based on light from a limited area of the photographic screen, and therefore has the disadvantage that the color balance of the main subject is easily influenced by the color of the background.

On the other hand, with the external light method, the color temperature is detected using not only the light from the photographic screen but also light from a wide range of surrounding areas as input light, so the above-mentioned drawbacks of the TTL method can be solved. If the light incident on the color temperature sensor is different from the light illuminating the subject, white balance adjustment becomes inaccurate, and it is also susceptible to backlighting.

[Problem to be solved by the invention]

As mentioned above, conventionally used automatic white balance adjustment devices, whether using external light method or TTL method, each have their advantages and disadvantages, and depending on the shooting scene, it may not be possible to obtain an image with well-corrected color balance. There are many cases.

The present invention was made taking these circumstances into consideration, and T
It is an object of the present invention to provide an electronic still camera that can reliably obtain an image with well-corrected color balance even if an automatic white balance adjustment device of either the TL method or the external light method is used.

[Means to solve the problem]

In order to achieve the above object, the present invention not only has a normal shooting mode in which one image is recorded by correcting the primary color signal using a correction value corresponding to the color temperature detected by a color temperature sensor, but also a mode corresponding to the color temperature. In addition to the above correction value, the primary color signals output from the image sensor are adjusted with other correction values that increase or decrease this correction value, and each video is produced with different color corrections performed by a single release operation. This allows shooting even in a continuously variable white balance shooting mode in which images are recorded multiple times based on a signal.

The above object also includes a correction width manual means for inputting a correction width ΔM for increasing or decreasing the correction value M0 corresponding to the color temperature obtained by the color temperature detection sensor, and a correction width manual means for inputting a correction width ΔM corresponding to the color temperature obtained by the color temperature detection sensor, and a number of times N of image recording repeated by one release operation. recording number input means for inputting the number of recordings; and the correction values M0 and M0±nΔM.
This can also be achieved by providing a control means for recording an image N times while correcting the primary color signal based on (n=1.2°...).

[Effect]

According to the above configuration, when a single release operation is performed under the continuously variable white balance shooting mode, in addition to the correction value corresponding to the detected color temperature, another correction value that is an addition or subtraction of this correction value is generated. However, the primary color signals are adjusted and each of these video signals automatically causes multiple image recordings. Therefore, the plurality of image recordings includes image recording in which the white balance has been properly adjusted, making it possible to obtain a reproduced image with good color balance.

Furthermore, the correction width ΔM for increasing/decreasing the correction value corresponding to the detected color temperature and the number of times N of image recording performed by - times of release operations may be set in advance, but these values may be set in advance. By providing a correction width input means and a recording number input means so as to be able to freely change the white balance, it is possible to freely adjust the white balance in consideration of the shooting scene and the like.

An embodiment of the present invention will be described below with reference to the drawings.

〔Example〕

In FIG. 2 showing the external appearance of an electronic still camera using the present invention, on the front side of the main body 2 of this electronic still camera, there is a photographing lens 11 and a color that receives light from the photographing screen and its surroundings in an external light manner. A light receiving window 14 for a temperature sensor is provided. A diffuser plate is used for this light receiving window 14, and the light receiving window 1
Diffused external light enters the sensor part 13 located at the fourth rear.

A release button 41, a liquid crystal panel 5 for displaying various photographic information, and an operation panel 6 are provided on the upper surface of the grip section 3, which is connected to the main body section 2.

The operation panel 6 includes a mode setting button 7, shooting number setting buttons 8B and 8R1, and a correction step width setting button 9.
is provided. As described in detail later, the mode setting button 7 has two modes: a normal shooting mode in which one shot is taken with standard white balance adjustment when the release button 4 is pressed once, and a normal shooting mode in which one shot is taken with standard white balance adjustment. This mode is for selecting one of the continuously variable white balance shooting modes in which shooting is repeated multiple times while changing the degree of shooting.

In addition, the number of shots setting buttons 8B and 8R are operated to set the number of shots to be taken while changing the degree of standard white balance adjustment when the white balance is continuously variable. Ru. The correction step width setting button 9 is used when changing the correction width for white balance adjustment under the continuously variable white balance shooting mode.

This electronic still camera is equipped with a single-lens reflex camera type finder device 15 including a movable mirror, and can observe a subject image as an optical image through a finder eyepiece frame 16.

FIG. 1 shows the electrical configuration used in the electronic still camera. A CCD 20 for capturing a color image is arranged behind the photographing lens 11, and the finder device 1
When the movable mirror 5 is raised, a subject image is formed on the photocathode of the CCD 20 by the photographing lens 11.

A preamplifier 21 is connected to the CCD 20, and the CC
The primary color signals B, G, and R of the blue, green, and red components output from the D20 are amplified and output to the process amplifier 22 at the next stage.

The process amplifier 22 amplifies the primary color signals B, G, and R from the preamplifier 21 with amplification factors C, , C, respectively.

G11 amplifies the signals and inputs them to the matrix circuit 23.゛Although the amplification factor G6 for the green component primary color signal G is constant, the primary color signal B.

The amplification factors Gtr and G* for R are adjusted depending on the color temperature of the light source illuminating the subject.

~ The matrix circuit 23 performs gamma correction on the primary color signal supplied from the process amplifier 22.

Perform matrix calculations. A color encoder 24 is connected to the matrix circuit 23, and the color encoder 24 outputs the signal supplied from the matrix circuit 23 as an NTSC format video signal. The video signal thus obtained is magnetically recorded on a still video floppy by the recording circuit 25.

The sensor part 13 includes a blue sensor and a red sensor, and detects the ratio of blue light and red light contained in external light. A color temperature detection circuit 26 is connected to the sensor part 13, and the color temperature corresponding to the detection signal from the sensor part 13 is expressed as a mired value (M9 when the color temperature value is in Kelvin, M-10"). The mired value thus detected is input to the microcomputer 27, and the microcomputer 27 sends a correction signal set corresponding to this mired value to the D/A converters 29m, 29m. This allows the amplification factors Cm and G1 of the process amplifier 22 for the primary color signals B and H to be adjusted.

The microcomputer 27 includes a mode setting button 7 and a shooting number setting button 8B shown in FIG.

8R1 is further connected to a key matrix circuit 28 for detecting the operating state of the correction step width setting button 9, and data is input to the microcomputer 27 by operating these buttons. Also, microcomputer 2
7 automatically adjusts the correction signal supplied to the process amplifier 22 in accordance with the data input from the key matrix circuit 28. Furthermore, drive pulses from the microcomputer 27 are also supplied to the CCD driver 30 for driving the C0D20, and during continuous shooting, the drive pulses from the microcomputer 27 drive the C0D.
D20 is driven at regular time intervals and repeats imaging each time.

Regarding the operation of an electronic still camera configured in this way,
This will be explained with reference to the time chart shown in FIG.

When the mode setting button 7 is set to the normal shooting mode and the release button 4 is operated, the color temperature detection circuit 26 detects the standard milled temperature that is used as a reference when adjusting the white balance in response to the detection signal from the sensor part 13. The value M0 is output to the microcomputer 27. The microcomputer 27 receives the primary color signal B associated with this standard mired value M0.

The standard amplification factor B-, Re of R is converted to A/D converter 29-.
It is supplied to the process amplifier 22 via 29R. Therefore, in this case, the primary color signal B from the preamplifier 21 is generated by one release operation.

G and R are the amplification factors Gyo (=B
O), cG, c* (=RO), and one image recording is performed using this video signal.

On the other hand, when it is expected that the automatic white balance adjustment device alone will not be able to properly correct the color balance, such as when photographing a subject in a room with fluorescent lights and near a window illuminated by sunlight. , set the mode setting button 7 to continuously variable white balance shooting mode, and use the correction step width setting button 9 to set the standard milled value M0.
Input the correction step width ΔM when changing stepwise. Furthermore, set the number of times nIl to take pictures while decreasing the standard mired value M0 (in the direction of increasing the color temperature) using the number of shots setting button 8B, and take pictures while increasing the standard mired value M0 (in the direction of decreasing the color temperature). Number of times nl
Set the number of shots using the number of shots setting button 8R.

In this way, mode setting button 7, number of shots setting button 8B
, 8R, data from the correction step width setting button 9 is input to the microcomputer 27, and when the release button 4 is operated once in this state, the total number of shots N ( ”' nl
+nR+1) is calculated, N times of imaging are performed consecutively. These N times of photography are carried out using the CCD from the microcomputer 27 while the movable mirror is in the raised state.
This is executed by supplying a drive pulse to the driver 30.

While the photographing is repeated N times in this way, the microcomputer 27 informs the amplification factor Cm of the process amplifier 22.
, Gi are outputted. That is, while the photographing is repeated N times, the microcomputer 27 adjusts the millimeter correction Mi (-Mg + (i
ns ) ·ΔM) is supplied to the process amplifier 22 . Therefore, the process amplifier 22 is
The amplification factors C, , GR for the primary color signals B, R are changed stepwise for each photograph. As a result, in addition to color correction photography corresponding to the standard mired value M0, color correction n corresponding to a mired value that is lower than the standard mired value M0 by an integer multiple of the correction step width ΔM.

Furthermore, n1 images of color correction are performed corresponding to a mired value that is higher than the standard mired value M0 by an integer multiple of the correction step width ΔM.

Of course, it is also possible to set one of the number setting buttons 8B and 8R to "O" to perform nm and nR imaging of only the standard Mired value M0 and those with higher or lower Mired values. It is possible.

The illustrated embodiment has been described above, but when the white balance continuous variable mode is set as described above, C
Instead of repeating imaging N times with CD20, 1
The photoelectric signal obtained from the CCD 20 by the imaging is temporarily stored in the frame memory, and when this data is repeatedly read out N times, the amplification factor Gs of the process amplifier 22 is
Image recording may be performed by adjusting G* stepwise.

〔Effect of the invention〕

As described above, according to the electronic still camera using the present invention, when the continuously variable white balance shooting mode is selected, in addition to automatic white balance adjustment based on the color temperature detected by the color temperature sensor, Since image recording is performed multiple times while changing the color temperature in stages, it is possible to reliably obtain an image with well-corrected color balance without missing a photo opportunity.

In addition, by providing a correction width input means and a recording number input means, in the white balance automatic variable shooting mode, the correction width ΔM that increases or decreases the color temperature M0 detected by the color temperature sensor and different color corrections are provided. Since the number of times N of image recording is performed can be arbitrarily set, it is possible to freely adjust the white balance according to the photographer's intention while using a conventional automatic white balance adjustment device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the electrical configuration of an embodiment of an electronic still camera of the present invention. FIG. 2 is a perspective view showing an embodiment of the electronic still camera of the present invention. FIG. 3 is a flowchart showing the photographing process of the electronic still camera shown in FIG. 2...Main unit 7...Mode setting buttons 8B, 8R...Number of shots setting button 9...Correction step width setting button 11...Photographing lens 13...Sensor part 27...Microcomputer 28... key matrix circuit.

Claims (2)

[Claims] (1) The color temperature is detected from the shooting screen or light from the surroundings including the shooting screen, and the primary color signal output from the image sensor is adjusted with a correction value corresponding to the color temperature to record an image using a color-corrected video signal. In an electronic still camera configured to perform In addition to the correction value corresponding to the color temperature, the primary color signal is adjusted with another correction value that increases or decreases this correction value, and images are recorded multiple times using each video signal that has undergone different color corrections. An electronic still camera characterized by having a continuously variable white balance shooting mode. (2) The color temperature is detected from the shooting screen or light from the surroundings including the shooting screen, and the primary color signal output from the image sensor is adjusted with a correction value M_0 corresponding to the color temperature to produce an image using a color-corrected video signal. In an electronic still camera configured to perform recording, a correction width input means for inputting a correction width ΔM for increasing or subtracting the correction value M_0, and a recording unit for inputting the number N of image recording to be repeatedly performed by one release operation. a number of times input means, the correction value M_0 and the adjusted correction value M_0;
1. An electronic still camera comprising: control means for recording images N times using video signals obtained by color-correcting primary color signals for each of ±nΔM (n=1, 2, . . . ).