JPS59183590A - Electronic still camera storing white balance information - Google Patents

Abstract

PURPOSE:To attain excellent picture reproduction by storing white balance information on each screen to reproduce a picture signal subject to color modulation outputted from an image pickup element of an electronic still camera. CONSTITUTION:A white balance information detector 22 is provided near the image pickup element 2 and constituted, e.g., by three photo diodes. A filter transmitting R,G,B spectrums only is adhered on the surface of the photo diodes, this output represents the intensity of R,G,B light when the camera picks up an object without color and is converted into required information by a code generator 20 as the white balance information. The output of the code generator 20 is stored in a memory 5 by changing over a switch 21 at a time other than the time when the picture signal is recorded in the memory by a synchronizing signal generator 18 and a control circuit 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic still camera that is capable of reproducing good images even under different lighting conditions during photography.

In a patent application titled "Child Still Camera" dated the same date as the present application, the inventors convert two-dimensional image information into an image signal using an image sensor, convert this image signal from AD to
We have proposed an electronic still camera that stores converted digital image information in a removable storage means. Since this electronic still camera digitally processes image signals, high-quality still images can be obtained without signal deterioration during signal processing, and since digital image data is stored in memory such as semiconductor memory, a rotation mechanism is not required. In addition to reducing power consumption, making the camera body more compact, and improving reliability, various signal processing is performed by the playback device, which increases the degree of freedom in signal processing and allows processing of playback images. Better than a camera. Of course, the present invention can also be applied to an electronic still camera using a memory such as a magnetic disk, which requires a mechanism section. Figure 1 shows the basic circuit configuration of this electronic still camera.
1 is an optical lens that forms an optical image of a subject; 2 is an image sensor that photoelectrically converts the optical image (two-dimensional image information) formed on the light receiving surface by the optical lens 1 and outputs it as an analog image signal; Generally known ones include image pickup tubes such as Sachicon, Vidicon, Branbicon, Cosbicon, and New Cosbifun, and solid-state image pickup devices such as CCD, MOS, and CPD. A color filter 2a is attached to the light receiving surface of the image sensor 2 so that a color image can be obtained. The image sensor 2 outputs an analog image signal in response to a drive signal from a driver 3, and this image signal is converted into a digital signal at high speed by an A/D converter 4. In this case, the quantization level is determined by the required image quality,
A typical television image requires about 8 bits. The sampling rate is generally based on the color subcarrier (
A sampling rate of 2 to 4 times 3.58 MI(z) is required, but this is not necessarily the case in electronic still cameras where the imaging section has a temporary storage function.

The image signal digitally converted by the A/D converter 4 is stored in the memory 5iC. As this memory 5,
Anything that can store digital signals stably
, N-MO8RAMSC-MOS RAM, CC
In addition to semiconductor memories such as D memory, magnetic bubble elements, magnetic disks, magnetic tapes, etc. are used. Writing and reading of image signals to and from the memory 5 is performed by a driver circuit 6.
controlled by The memory 5 is, for example, in the form of a cassette, which is replaceable and can be attached to and removed from the camera at a predetermined position on the camera body.

On the other hand, the digital image signal output from the A/D converter 4 is directly or once stored in the memory 5 and then converted into an analog image signal by the D/A converter 7. sent to
Here, the image is displayed on a monitor CRT.

In this case, the selector switch 8 is set by the driver 6 by external operation.
Contacts a and b are switched by a switching signal from. In addition, the output of the image sensor 2 is directly connected to the changeover switch 8 (contact a).
It is also possible to visualize the image using the electronic finder 9 via the electronic viewfinder 9. In this case, since the output of the image sensor 2 is modulated by the color filter 2a, when the image is displayed directly on the electronic viewfinder 9, it is different from a normal black and white image, but it is possible to know what is being displayed. .

Note that 10 is a battery that serves as a power source for each of the circuit elements described above.

FIG. 2 is a block line of one embodiment of the playback device, in which the memory 5 is removed from the camera and the playback W4 (shown surrounded by a broken line).
is set in the specified position.

In the playback machine, the microcomputer 12 reads the image data recorded in the memory 5 according to the software in the ROMI 31 in the memory 13 containing a built-in program for playback, and uses the RAMI 32 in the memory 13 as a work area. Process data. Processed data is written to the field memory 14 according to instructions from the microcomputer 12, and this field memo IJ14
Except when accessed by the V1 microcomputer 12, it is always driven by the television rate drive circuit 5, and its output is displayed as an image on the monitor 17 via the D/A converter 16. As a result, the recorded video gradually appears on the monitor 16.

In the Tamaki electronic still camera, a three-color color filter 2a for color separation is attached to the light-receiving surface of the image sensor 2 that converts two-dimensional image information into an image signal. The signal is color-modulated and output as an analog image signal containing color information, and then converted into a p-digital signal by the A/D converter 4 and stored in the memory 5. Color separation can be performed by digitally processing image signals in this manner.

By the way, in order to perform the above-mentioned signal reproduction well, a process called white balance is necessary. Normal television cameras and electronic still cameras have a color separation circuit inside the camera, and when an achromatic subject such as white, gray, or black is photographed, the color separation circuit separates the output of the image sensor into colors. For example, if the signals are separated into three signals, R, G, and B, then in the white balance circuit, R
, G, and H so that the amplitudes of R and H match the amplitude of the G signal. This ensures that the camera's output maintains good color reproduction.

However, in the electronic still camera shown in FIG. 1, the image signal output from the image sensor 2 is simply A/D converted and stored in the memory 5, so white balance processing cannot be performed within the camera.

The invention was made in view of the above points, and a circuit for detecting all the information for white balance is provided in the camera part, and the white balance information detected by this is recorded in the memory, and the playback device records it in the memory. White balance processing is performed within the playback device based on the white balance information obtained.

The present invention will be explained below based on the drawings.

FIG. 3 shows an embodiment of an electronic still camera in which information for performing white balance processing can be obtained, and the same reference numbers as in FIG. 1 indicate the same parts.

In the figure, reference numeral 22 denotes a white balance information detector provided near the image sensor 2, which is composed of, for example, three photodiodes.

A filter is pasted on the surface of this photodiode that passes only the R, G, and B light spectra, and when the camera photographs an achromatic object, the output is R, G, and B.
The strength of each party, G and B, is shown, and this is converted into required information by the code generator 20 as white balance information. The output of the code generator 20 is the synchronization signal generator 18
, the control circuit 19 records the image signal in the memory by switching the switch 21 at a time other than when the image signal is recorded in the memory 5. The following methods can be considered as methods for recording this information.

(1) Utilization of free space in memory: For example, when using an image sensor with a horizontal prime number of 385, the normal scanning line is often composed of 512 bytes for ease of signal processing, but this causes waste. A large memory area can be used to store white balance information.

(2) Scanning lines - Utilization of misfires: The image sensor information is scanned with 525 scanning lines, of which the first few and last few scan lines are displayed on the monitor screen of the playback machine. is not displayed. Therefore, it is possible to store white balance information in the area corresponding to this scanning line portion. (3) Utilization of horizontal or vertical retrace section: Mechanical disks, magnetic tapes, etc. are used as memory for electronic still cameras. If a memory having a drive mechanism is used, these memory media operate even during the retrace period, so white balance information can be stored in a portion of the memory medium corresponding to the retrace period.

The reproducing apparatus has the same configuration as that shown in FIG. 2, but during signal processing, for example, R and G after color separation processing.

B signal swing lll1i! Based on the signal amplitude of all G, R
Microcomputer software was added to adjust the amplitude of the 9B signal to change the amplification degree of the R and B signals based on the white balance data stored in the memory, and to maintain the white balance of the reproduced signal reproduced in the field memory.

Furthermore, FIG. 4 shows another method of obtaining this white balance information, in which the same reference numbers as in FIG. 1 indicate the same parts.

23 in the figure is a color temperature conversion filter turret. This is a filter that converts the color temperature of incident light and sends it to the image sensor.
Filter glasses 23a (only one filter glass is shown in the figure) are arranged.

When using an electronic still camera, first, an achromatic subject is photographed. At this time, the electronic viewfinder 9
Although the output varies depending on the configuration of the color filter 2a, it receives a predetermined brightness modulation by the color filter 2a. However, if the color temperature of the incident light differs, the white balance will be disrupted and the brightness modulation will no longer be a predetermined modulation.

While observing this with the electronic finder 9, the filter of the color conversion filter turret of the filter turret 23 is selected so as to approximate the predetermined brightness modulation. This will give you a rough idea of the white balance, but the white balance is not necessarily perfect.

Therefore, in order to eliminate this slight imperfection, a portion (for example, one line) of the modulated waveform of the image signal at this time is recorded in a memory. The recording location, etc. is the same as the method described above.

In the reproducing apparatus, a microcomputer calculates information for determining R and H gains for white balance from the information recorded in the memory. This calculation method differs depending on the configuration VC of the color filter 2a attached to the image sensor, but it can be uniquely determined by calculation.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the electronic still camera that is the subject of the invention, Fig. 2 is a schematic diagram of the playback device, Fig. 3 is a schematic diagram of the electronic still camera according to the invention, and Fig. 4 is a schematic diagram of the electronic still camera according to the invention. FIG. 2 is a block diagram of the playback machine shown with a memory set. DESCRIPTION OF SYMBOLS 1... Optical lens, 2... Image pickup element, 2a... Color filter, 3... Driver, 4-=A/D converter, 5.13... Memory, 6... Driver, 7 -D
/ A converter, 8.21... changeover switch, 9.
...Electronic finder, 10...Battery, 12...
Microcomputer, 14--Field memory,
15...TV rate drive circuit, 16...D/
A converter, l゛7... Monitor, 18... Synchronous signal generator, 19... Control circuit, 20... Coat generator, 22... Detector, 23... Color'tfA
Degree conversion filter target patent applicant Japan Broadcasting Association Konishi Rokuho Shin Kogyo Co., Ltd. Representative Patent Attorney Hiroo Tsuchi Suzuki

Claims (3)

[Claims] (1) Light from the subject is incident on the image sensor through an optical lens and color filter, the color-modulated image signal output from the image sensor is directly A-D converted, and the converted digital information is attached and detached. In the electronic still camera, white balance information for reproducing the color-modulated image signal is stored in the storage means for each screen. Electronic still camera. (2) The electronic still camera according to claim 1, wherein information obtained by analyzing a signal output from a detector or an image sensor that detects information on the color temperature of incident light is used as the white balance information. . (3) The electronic still camera according to claim 1, wherein the white balance information is stored in a memory area of one scanning line in the storage means that is not used for image output signals.