JP2002125241A - Still video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a still video camera adopting a digital recording system that can reduce a storage capacity of a semiconductor memory required when a digital image signal is stored in the semiconductor memory. SOLUTION: The still video camera is configured such that an imaging device applies photoelectric conversion to an optical image of an object obtained through an optical lens to obtain an image signal, and signal processing is applied to the image signal and compression processing is applied to the above image signal for each color on the basis of the correlation among adjacent pixels and then the memory stores the processed image signal. Thus, the still video camera can efficiently conduct the compression processing and save the storage capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a still video camera, which converts an analog image signal output from an image pickup device into an analog video signal.
The present invention relates to a still video camera configured to record a digital image signal obtained by the / D conversion in a memory.

[0002]

2. Description of the Related Art In recent years, in place of a conventional film camera, a still video having a structure 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. 2. Description of the Related Art A camera has been developed, and an electric image signal stored in a memory is reproduced and viewed on a monitor or hard-copyed by a printer.

[0003] 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 through an optical lens is photoelectrically converted by an image pickup device such as a CCD. The electrical image signal obtained by the conversion is subjected to analog processing such as color separation, gamma correction, line-sequentialization, and FM modulation, and then electromagnetically converted using a magnetic head or the like, and magnetically recorded on a magnetic disk.

[0004] 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 and electromagnetic conversion of the signal, 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, a digital signal obtained by A / D conversion of an electric image signal obtained by an image pickup device is stored in a semiconductor memory by the present applicant (Japanese Patent Application Laid-Open No. 59-1984). No. 183,582),
According to this, signal deterioration due to analog processing can be prevented, and a drive mechanism as in the case of a magnetic disk is not required, so that a camera and a reproducing device can be reduced in size and weight and cost can be reduced.

[0007]

By the way, in a still video camera configured to record digital image data in a semiconductor memory as described above, if the digital video data is recorded in the memory without performing a process such as color separation. (See FIG. 9), the circuit configuration is simplified as compared with a still video camera of the type that records analog data on a magnetic disk (see FIG. 10), and the camera is further reduced in size and cost in combination with the effect of omitting the drive mechanism of the magnetic disk. Down can be planned.

However, since the dynamic range of the output signal of the CCD 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, a gamma correction is performed before A / D conversion to compress the dynamic range of the CCD output signal to about 50 dB. It is necessary to be able to use it, and 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. It is difficult to judge from the image recording alone that the photographing conditions such as the type of the color filter in the color still video camera are different. Therefore, when a dedicated reproducing device is used with one type of camera, no major problem occurs. For example, if a memory in which images captured by a plurality of types of still video cameras having different color filters are respectively recorded is to be reproduced by a common reproducing device, a problem such that desired color separation is not performed occurs.

In a digital recording still video camera, it is important to reduce the storage capacity when storing digital image data in a semiconductor memory. The present invention has been made for the purpose of reducing such storage capacity.

[0011]

According to the first aspect of the present invention, an image signal obtained by photoelectrically converting an optical image of a subject obtained by an optical lens by an image pickup device is subjected to signal processing, and stored in a memory. A still video camera configured to be stored, wherein the image signal is subjected to a compression process for each color based on a correlation between adjacent pixels, and stored in the memory.

[0012]

Embodiments of the present invention will be described below.

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

Here, an optical image signal from an optical system 1 including a lens, an aperture, a shutter, an optical low-pass filter, an infrared cut filter, and the like is controlled by a drive circuit 2 and a drive timing generation circuit 7 by a CCD. And MOS
The analog image signal is converted into an electric image signal by an image sensor 3, the analog image signal is subjected to signal processing by an analog processing circuit 4, and then subjected to A / D conversion by an A / D converter 5. The data is recorded in the memory 6.

The memory 6 may be any memory card, a magneto-optical disk, a DAT, or the like which can record a digital signal such as a memory card detachable from a still video camera.

Here, in the analog processing circuit 4, C
The electrical image signal output from the image sensor 3 is converted into a baseband signal by a sample and hold circuit such as a DS (correlation double sampling) circuit, and the signal is output to the A / D converter 5.

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. The 8-bit device can be used as the device 5.

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

The conversion timing by the A / D converter 5 is as follows.
Since sampling is performed at the same frequency as the signal reading clock of the image sensor or a fraction of an integer thereof, all the clocks necessary for the A / D converter 5 are supplied from the drive timing generation circuit 7 of the image sensor 3.

Here, in the still video camera of the present embodiment, since the digital image signal is recorded in the memory without performing signal processing such as color separation and line sequentialization, the color is recorded on the reproduction device side as shown in FIG. 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 / A converted signals are processed by a process circuit).

Therefore, data necessary for performing signal processing such as color separation at the time of reproduction is stored in an image when an image is recorded.
As shown in (1), it is necessary to simultaneously record the information in a predetermined memory area in advance.

For example, in the case where the A / D converted 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 not stored. If it is not known which area is recorded at the time of reproduction, reproduction may not be possible. For example, as shown in FIG. 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.

In this way, even when the recording method is such that a plurality of image data are packed and stored in the order of addresses without dividing the memory area into image units, it is easy to access when reproducing. Become.

As in the present embodiment, a color filter is provided to extract 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) so that the arrangement of the color filters in the used still video camera can be understood.
And the minimum unit of the color filter array (or a code that can refer to the filter array) as shown in FIG. 6 (green, magenta, cyan, and yellow filters) is stored in a memory corresponding to each screen, The arrangement of the color filters of the still video camera from which the image was captured is read from the memory 6, and the color separation processing is performed according to the arrangement.

If the data indicating the arrangement of the color filters is stored in the memory 6 in this manner, even if the data obtained by the still video cameras having different arrangements of the color filters are mixed, 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, but in the still video camera of the present embodiment, the white balance adjustment is performed without performing such white balance adjustment. Need to do.

For this reason, information necessary for the adjustment includes, for example, the color temperature of the subject detected by the sensor, or RGB information.
RG if the camera has sensors corresponding to the three primary colors
Information such as the signal level of each color B and the deviation from the reference level is recorded in the memory 6 at the same time as the photographing, and the reproducing apparatus reads this information so that the white balance adjustment is properly performed.

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

Here, information necessary for the color separation processing is as follows:
For the spectral characteristics of infrared cut filters and color filters, do not directly record the characteristic values.
The model number, thickness, etc. may be recorded.

When the spectral characteristics of an optical system such as an optical lens and a quartz plate are stored, 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 photographing date / time data corresponding to the image recorded in the memory, the predicted photographing 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 pixel order as shown in FIG.
In a device provided with G and B color filters, pixels of a red R filter, pixels of a green G filter, and pixels of a blue B filter are collectively recorded in the memory for each of the three primary colors. The correlation between adjacent pixels appears, and the compression process can be performed more efficiently.

In a normal image pickup device, the number of optical black (OB) pixels serving as a black reference is 40 × 500 (2
0K), but it is not necessary to record all of them. For example, only one OB pixel is recorded per scanning line, or only one OB pixel is recorded in one image. As a result, the memory capacity can be saved.

Here, one OB pixel is set for one scanning line.
When only pixels are recorded, only one OB pixel is sampled from one scanning line, or the average of OB pixels (about 40 pixels) in one scanning line is calculated and the average value is calculated for one scanning line. When only one OB pixel data is recorded per image as OB pixel data for each line, an average of the whole is recorded.

Further, it is possible to record one pixel per one scanning line when the variation of the signal level of the OB pixel is large, and to record one pixel per one image when the variation is small.

[0041]

According to the first aspect of the invention, compression processing is performed based on the correlation between adjacent pixels of the same color, and digital image signals for each color are collectively recorded in the memory.
The compression process can be performed efficiently, and the storage capacity can be saved.

[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

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // H04N 101: 00 H04N 9/79 G (72) Inventor Masaaki Tsuchida 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Katsuya Nagaishi Inventor Katsuya Nagaishi 2970, Ishikawa-cho, Hachioji-shi, Tokyo F-term (reference) 2K054 AA01 5B057 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC01 CE11 CH12 5C022 AA13 AC42 AC54 AC55 5C055A06 BA03 BA06 CA07 EA02 EA05 EA06 EA17 EA18 FA01 5C065 AA03 BB02 BB03 CC01 CC08 DD01 EE05 EE06 EE07 GG27

Claims (2)

[Claims] An image signal obtained by subjecting a light image of a subject obtained by an optical lens to photoelectric conversion by an image pickup device,
A still video camera configured to perform signal processing and store in a memory, wherein the image signal is subjected to compression processing for each color based on a correlation between adjacent pixels, and stored in the memory. A still video camera characterized in that: 2. The still video camera according to claim 1, wherein said memory is a memory detachable from a camera body, and said camera body is configured so that said memory is detachable.