JP3103980B2 - Still video camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a still video camera, and more particularly, to a still video camera configured to record in a memory a digital image signal obtained by A / D converting an analog image signal output from an image sensor.

[0002]

[Prior art]

In recent years, instead of a conventional film camera, a still video camera has been developed in which an optical image signal from a subject is converted into an electric image signal by an image sensor and the electric image signal is stored in a memory corresponding to a film. The image signal stored in the memory is reproduced and viewed on a monitor,
Or to make a hard copy on a printer.

A magnetic disk is generally used as a memory of such a still video camera. In this case, for example, an optical image signal obtained by passing through an optical lens is photoelectrically converted by an image pickup device such as a CCD. The electric image signal obtained by the conversion is subjected to analog processing such as color separation, gamma correction, line-sequencing, FM modulation, and the like, and then electromagnetically converted using a magnetic head or the like, and magnetically recorded on a magnetic disk.

At the time of reproduction, a magnetic signal recorded on a magnetic disk is electromagnetically converted, analog processed, and displayed on a monitor.

However, such a method of magnetically recording an analog signal on a magnetic disk requires analog processing of the signal and electromagnetic conversion, so that the signal is liable to be deteriorated. The necessity of the rotary drive mechanism inevitably increases the size and cost, and, apart from business use, causes a delay in the spread of consumer use.

In view of this point, the present applicant has proposed a digital signal obtained by A / D-converting an electric image signal obtained by an image sensor into a semiconductor memory (Japanese Patent Application Laid-Open No. 59-1984). According to Japanese Patent Application Laid-Open No. 183582), it is possible to prevent signal deterioration due to analog processing and to eliminate the need for a drive mechanism as in the case of a magnetic disk. .

[0007]

[Problems to be solved by the invention]

By the way, in a still video camera having a configuration in which digital image data is recorded in a semiconductor memory as described above, if recording is performed in a memory without performing a process such as color separation (see FIG. 9), the digital video data is recorded on a magnetic disk. The circuit configuration is simplified as compared with a still video camera of the analog recording type (see FIG. 10), and the camera can be further downsized and the cost can be further reduced in combination with the effect of omitting the drive mechanism of the magnetic disk.

However, since the dynamic range of the CCD output signal is 70 dB or more, the number of bits at the time of A / D conversion needs to be about 12 bits or more in order to secure the resolution.
Since an A / D converter is required, gamma correction is performed before A / D conversion to compress the dynamic range of the CCD output signal to about 50 dB, thereby achieving an A / D converter of 8
You need to be able to use something about a bit,
It is better not to omit the gamma correction circuit.

As described above, in the digital recording still video camera, the signal processing is omitted as much as possible and the recording is performed in the memory, so that the circuit configuration on the camera side can be simplified (however, the burden on the reproducing side is reduced). However, it is difficult to judge from the image recording alone that the photographing conditions such as the type of the color filter in the single-panel color still video camera are different. Although no major problems occur when using a playback device, for example, when a memory in which images captured by a plurality of types of still video cameras having different color filters are recorded is to be reproduced by a common playback device, desired color separation is performed. And other problems occur.

The present invention has been made in view of the above problems, and in a still video camera for recording a digital image signal, a signal processing circuit is omitted as much as possible, and even when shooting conditions are different, an intended image is reproduced. An object is to enable signal processing.

[0011]

[Means for Solving the Problems]

Therefore, in the invention according to claim 1, a digital image obtained by converting an optical image of a subject obtained by an optical lens into an electric image signal by an image pickup device and A / D converting the electric image signal by an A / D converter. In a still video camera configured to store a signal in a memory, the memory is detachably provided to a camera body, and the digital image signal and information for white balance adjustment including color temperature information of a subject are stored in the camera. The recording is performed in different areas of the memory.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described.

FIG. 1 shows a system configuration of a still video camera according to an embodiment.

Here, an optical system 1 including a lens, an aperture, a shutter, an optical low-pass filter, an infrared cut film, and the like.
An image sensor 3 such as a CCD or a MOS controlled by a drive circuit 2 and a drive timing generation circuit 7
The analog image signal is converted into an electric image signal by the analog processing circuit 4, and then A / D converted by the A / D converter 5. The converted digital image signal is recorded in the memory 6. It has become so.

The memory 6 may be a memory card, a magneto-optical disk, a DAT or the like capable of recording a digital signal, such as a memory card detachable from a still video camera and configured as a card in a semiconductor memory.

Here, the analog processing circuit 4 converts an electric image signal output from the image sensor 3 into a baseband signal by a sample-and-hold circuit such as a CDS (correlation double sampling) circuit, and converts the signal into an A / D converter. 5 to output the signal.

When only the sample and hold as described above is performed and no other signal processing is performed, the signal can be converted into a digital signal by using an A / D converter 5 of 12 bits or more. The configuration is simplified.

However, if the data is recorded in the memory with 12 bits, there is a problem that the memory capacity required for image recording is increased. In this case, for example, the gamma correction is performed before or after the A / D converter 5. The data amount may be reduced by performing signal compression processing as described above.

If the output signal of the image sensor 3 is subjected to gamma correction in analog before the A / D converter 5, the dynamic range can be reduced from 70 dB or more to about 50 dB.
An 8-bit A / D converter can be used.

Further, as shown in FIG. 3, if an A / D converter having an A / D conversion characteristic with a gamma characteristic is used, the A / D conversion and the gamma correction can be performed at the same time. Can be simplified.

Since the conversion timing by the A / D converter 5 is sampled at the same frequency as the signal reading clock of the image sensor or a fraction of the integer, all clocks required by the A / D converter 5 are 3 from the drive timing generation circuit 7.

Here, in the still video camera of the present embodiment, a digital image signal is recorded in a memory without performing signal processing such as color separation and line sequentialization. A process circuit 11 for performing signal processing such as separation is provided. A digital image signal processed by the process circuit 11 is converted into an analog signal by a D / A converter 12 and output as a television signal (or D). / A process the signal converted by the process circuit).

Therefore, it is necessary to simultaneously record data necessary for performing signal processing such as color separation during reproduction in a predetermined memory area as shown in FIG. 7 when an image is recorded.

For example, in the case where the A / D conversion value of the output signal of the image sensor 3 is recorded almost as it is as described above, where the pixel number is in the memory, in other words, the data for one screen is If it is not known at the time of reproduction which area is recorded at the time of reproduction, reproduction may not be possible. For example, as shown in FIG. 4, a screen number (photographing order) indicates at which address the four corners of one screen are stored. May be stored in a predetermined area of the memory, and data may be read by referring to the address at the time of reproduction.

There is also a method in which one screen is sequentially recorded as one pixel row, and the addresses of the first pixel and the last pixel are stored in a predetermined area. In this case, only the first address may be stored, and the first pixel of the next screen may be located immediately after the last pixel.

With this configuration, even when a recording method is adopted in which a plurality of image data are packed and stored in address order without dividing the memory area into pixel units, it is easy to access when reproducing. Become.

As in the present embodiment, a color filter is provided in order to take out a color signal from the single-chip image sensor 3. However, if the color arrangement in the color filter is not known, color separation processing is performed during reproduction. 5 (R, G, B filters) and FIG. 6 (green, green) so that the arrangement of the color filters in the used still video camera can be understood.
The minimum unit of the color filter array (or a code that can refer to the filter array) as shown in magenta, cyan, and yellow filters is stored in a memory corresponding to each screen. The arrangement of the color filters is read from the memory 6, and the color separation processing is performed according to the arrangement.

As described above, if the data indicating the arrangement of the color filters is stored in the memory 6, even if there is a mixture of still pictures taken by a still video camera having different arrangements of the color filters, the reproduction device Since this can be determined on the side, a common reproducing apparatus can be used between a plurality of types of still video cameras having different filter arrangements.

In a video camera, white balance adjustment is generally performed. However, in the still video camera of the present embodiment, the white balance adjustment is not performed, and the still image is recorded in the memory 6.
It is necessary to adjust the white balance on the playback device side.

For this reason, the information necessary for the adjustment includes, for example, the color temperature of the subject detected by the sensor, or the signal level or reference level of each RGB color if the camera is equipped with a sensor corresponding to the three primary colors of RGB. The information such as the deviation is recorded in the memory 6 at the same time as the photographing, and is read into this information on the reproducing apparatus side so that the white balance adjustment can be performed well.

Other photographing conditions stored in the memory 6 together with photographing include, for example, the spectral characteristics of the color filters,
Number of pixels (total number of pixels, number of active pixels) of image sensor 3, spectral characteristics of infrared cut filter. Examples include the spectral characteristics of the optical system, shooting time and date.

Here, instead of directly recording the characteristic values of the infrared cut filter and the color filter, the manufacturer's name, model number, thickness, etc. may be recorded.

When storing the spectral characteristics of an optical system such as an optical lens or a quartz plate, the spectral characteristics recorded in the memory are read out, and the three primary color signals are corrected based on the spectral characteristics. good.

Further, based on the shooting date and time data corresponding to the image recorded in the memory, the predicted shooting environment is reflected in the color reproduction, for example, in the evening, the red of the reproduced image is increased. In this case, the weather may be estimated from the shooting time and the color temperature recorded for white balance adjustment and reflected in the color reproduction.

Further, information such as a photographing place and weather may be recorded in a memory in association with an image by a photographer's operation.

On the other hand, the photographing conditions are recorded in the memory together with the image data as described above, and the following measures are taken in recording the image data so that more efficient signal processing or saving of the recording capacity is performed. It is desirable to do.

Normally, when image data is recorded in the memory, it is recorded in the order of pixels as shown in FIG. 8. For example, in the case of having R, G, B color filters, pixels of the red R filter, green G
If the pixels of the filter and the pixels of the blue B filter are collectively recorded in the memory for each of the three primary colors,
Correlation between adjacent pixels of the same color appears, so that the compression process can be performed more efficiently.

In a normal image pickup device, there are approximately 40 × 500 (20K) pixels for optical black (OB) serving as a black reference. However, it is not necessary to record all the pixels. By recording only one pixel for the object, or by recording only one pixel for the OB in one image,
It is also possible to save memory capacity.

Here, when only one OB pixel is recorded for one scanning line, only one OB pixel is sampled from one scanning line, or one OB pixel in one scanning line ( In the case of recording only one OB pixel data per image by taking an average of about 40 pixels) and taking the average value as OB pixel data for each scanning line, an average of the entire data is taken. I do.

Further, it is also possible to record one pixel for each scanning line when the variation in the signal level of the OB pixels is large, and to record one pixel for each image when the variation is small.

[0041]

【The invention's effect】

According to the first aspect of the present invention, in a still video camera configured to record a digital image signal in a memory, white balance adjustment information including color temperature information of a subject is read from the memory on the playback device side, and the white balance adjustment is performed. Since the balance adjustment can be performed, the still video camera can record the digital image signal in the memory without performing the white balance adjustment. There is an effect that white balance adjustment can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a still video camera according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a playback device in the embodiment.

FIG. 3 is a diagram showing conversion characteristics of an A / D converter.

FIG. 4 is a diagram showing characteristics when recording a recording location of image data.

FIG. 5 is a color filter distribution diagram showing a minimum unit when recording the type of a color filter.

FIG. 6 is a color filter distribution diagram showing a minimum unit when recording the type of a color filter.

FIG. 7 is a diagram showing a recording area of a photographing condition in a memory.

FIG. 8 is a recording processing state diagram showing a state of recording for each filter color.

FIG. 9 is a block diagram showing a conventional example of a digital recording still video camera.

FIG. 10 is a block diagram showing a conventional example of an analog recording still video camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical system 2 ... Drive circuit 3 ... Image sensor 4 ... Analog processing circuit 5 ... A / D converter 6 ... Memory 7 ... Drive timing generation circuit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Katsuya Nagaishi, Inventor 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Co., Ltd. Examiner Yosuke Kikata (56) References JP-A-59-183592 (JP, A) JP-A Sho 60-12880 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/225-5/247 H04N 5/76-5/956 H04N 9/79-9/898

Claims (1)

(57) [Claims] An image pickup device converts an optical image of a subject obtained by an optical lens into an electric image signal, and converts the electric image signal into a digital image signal by an A / D converter. In a still video camera configured to store, the memory is detachably provided to a camera body, and the digital image signal and information for white balance adjustment including color temperature information of a subject are stored in different memories. A still video camera characterized by recording in each area.