JPH0338986A - Still video camera - Google Patents

Abstract

PURPOSE:To execute initial signal processing even when pictures are reproduced by providing a signal processing circuit, which is omitted on a camera side, on a reproducing machine side and to make operation corresponding to the reproducing of picture records under various photographic conditions by recording the photographic condition to a memory together with the pictures. CONSTITUTION:An optical picture signal from optics 1 is converted to an electric picture signal by an image pickup element 3 and signal processing is executed to this analog picture signal by an analog processing circuit 4. Afterwards, A/D conversion is executed to this analog picture signal by an A/D converter 5 and after the conversion, a digital picture signal is recorded to a memory 6. At such a time, the photographic condition is recorded to the memory together with the record of the digital picture signal. Thus, when the photographic condition to be required for executing the various kinds of signal processing on the reproducing side is recorded, it is possible to prevent that the initial processing can not be executed by the lack of information in case the signal processing is executed on the reproducing side with circuit configuration omitted on the camera side. Then, more suitable reproducing can be executed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a still video camera, which is configured to record in a memory a digital image signal obtained by A/D converting an analog image signal output from an image sensor. Use a still video camera.

<Conventional technology> In recent years, in place of conventional film cameras, optical image signals from a subject are converted into electrical image signals using an image sensor.
A still video camera has been developed that stores the electrical image signals in a memory equivalent to film, and the electrical image signals stored in the memory can be played back and viewed on a monitor or printed as hard copies using a printer. ing.

A magnetic disk is generally used as memory for such still video cameras, and in this case, for example, an optical image signal obtained by passing through an optical lens is photoelectrically converted by an image sensor such as a CCD, and the image is converted into an image by the conversion. Color separation of the electrical image signals obtained.

After performing analog processing such as gamma correction, line sequentialization, and FM modulation, the data is subjected to electromagnetic conversion using a magnetic head or the like and magnetically recorded on a magnetic disk.

Furthermore, during playback, magnetic signals recorded on a magnetic disk are electromagnetically converted, processed into analog signals, and displayed on a monitor.

However, this method of magnetically recording analog signals on magnetic disks tends to cause rounding and signal deterioration, which requires analog signal processing and electromagnetic conversion.
Since both the camera and the player require a rotating drive mechanism for the magnetic disk, they inevitably become larger and more expensive, which is a cause of delay in their widespread use for consumer use as well as for business use.

In view of this, the applicant has proposed a system in which a digital signal obtained by A/D converting an electrical image signal obtained by an image sensor is stored in a semiconductor memory (
According to this, it is possible to prevent signal deterioration due to analog processing, and
Since there is no need for a drive mechanism like in the case of magnetic disks, cameras and playback devices can be made smaller and lighter, and cost reductions can be achieved.

<Problems to be Solved by the Invention> By the way, in a still video camera configured to record digital image data in a semiconductor memory as described above, it is possible to configure the still video camera to record digital image data in the memory without performing any processing such as color separation. (See Figure 9) Compared to a still video camera that records analog data on a magnetic disk (see Figure 10), the circuit configuration is simplified, and this combined with the effect of omitting the magnetic disk drive mechanism allows for further miniaturization of the camera. Cost reduction can be achieved.

However, the dynamic range of the CCD output signal is 70d.
Since there are more than B, the number of bits during A/D conversion needs to be about 12 bits or more to ensure resolution, and an expensive A/D converter is required.
By compressing the dynamic range of the COD output signal to about 50 dB by applying gamma correction before A/D conversion, it is necessary to make it possible to use about 8 bits as an A/D converter. It is better not to omit it.

In this way, in a digital recording still video camera, by configuring the camera to record in memory without signal processing as much as possible, the circuit configuration on the camera side can be simplified (
However, the burden on the playback side increases. ) However, it is difficult to judge from image recording alone that the shooting conditions such as the type of color filter in a single-chip color still video camera are different, so it is difficult to determine from image recording alone that a dedicated playback device is used with a Class 111 camera. Although this does not cause any major problems when used, for example, if you try to play back on a common playback device a memory containing images taken with multiple types of still video cameras with different color filters, the expected color separation may not be performed. Problems such as not being available may occur.

The present invention has been made in view of the above-mentioned problems, and it is possible to omit signal processing circuits as much as possible in a still video camera that records digital image signals, and to perform desired signal processing during playback even under different shooting conditions. The purpose is to do so.

<Means for Solving the Problems> Therefore, in the present invention, an optical image signal of a subject obtained by an optical lens is converted into an electrical image signal by an image sensor, and further A/D converted by an A/D converter. In a still video camera configured to store digital image signals in a memory, the camera is configured to record photographing conditions in the memory along with recording the digital image signals.

<Operation> According to this configuration, since the shooting conditions are recorded together with the digital image signal, if the shooting conditions necessary for performing various signal processing on the playback side are recorded, the omitted circuit configuration on the camera side can be used. When performing signal processing on the reproduction side, it is possible to avoid the inability to perform the intended processing due to lack of information, and it is also possible to perform more appropriate reproduction.

<Example> The present invention will be explained in detail below.

FIG. 1 shows the system configuration of a still video camera in one embodiment. Here, the lens.

An optical image signal from an optical system 1 consisting of an aperture, a shutter, an optical low-pass filter, an infrared cut filter, etc. is transmitted to an image sensor such as a CCD or MOS, which is controlled by a drive circuit 2 and a drive tie generation circuit 7. 3, the analog image signal is converted into an electrical image signal by an analog processing circuit 4, and then converted into an electrical image signal by an A/D converter 5.
The digital image signal is D-converted and the converted digital image signal is recorded in the memory 6.

The memory 6 may be any device capable of recording digital signals, such as a memory card in which a semiconductor memory is structured in the form of a card and can be attached to and detached from a still video camera, a magneto-optical disk, or a DAT.

Here, in the analog processing circuit 4, the electrical image signal outputted from the image sensor 3 is converted into a baseband signal by a sample hold circuit such as a CD5 (correlated double sampling) circuit, and the baseband signal is sent to the A/D converter 5. Output a signal.

Here, when performing only sample and hold as described above and no other signal processing, it is possible to convert to a digital signal using a 12-bit or more A/D converter 5, and in this case, the quantity also increases. The circuit configuration is simplified. however,! If 2 bits are recorded in the memory as they are, there is a problem that the memory capacity required for image recording will increase. You can reduce the amount of data by performing compression processing.

Furthermore, by applying analog gamma correction to the output signal of the image sensor 3 before the A/D converter 5, the dynamic range can be compressed from 70 dB or more to about 50 dB. 8-bit data can be used as Furthermore, as shown in Figure 3, by using an A/D converter that has gamma characteristics in its A/D conversion characteristics, A/D conversion and gamma correction can be performed simultaneously, simplifying the circuit configuration. can be converted into

The conversion timing by the A/D converter 5 is sampled at a frequency that is the same as the signal readout clock of the image sensor or an integer fraction thereof, so all necessary locking in the A/D converter 5 is done by driving the image sensor 3. It is supplied from the timing generation circuit 7.

Here, in the still video camera of this embodiment, since digital image signals are recorded in the memory without signal processing such as color separation or line sequentialization, color separation and other processing are performed on the playback device side as shown in Fig. 2. A process circuit 11 is provided which performs signal processing, and the 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 The converted signal is then processed by the processing circuit).Therefore, when the image is recorded, the data necessary to perform signal processing such as color separation during playback is processed as shown in Figure 7. It is necessary to simultaneously record them in a predetermined memory area in advance.

For example, as described above, A/, D of the output signal of the image sensor 3
With devices that record converted values almost as-is, there is a possibility that playback will not be possible if you do not know where and what pixel is in the memory, or in other words, which area is recorded from one screen of data at the time of playback. For example, the fourth
As shown in the figure, the addresses at which the four corners of one screen are stored are stored in a predetermined area of memory in correspondence with the screen number (shooting order), and during playback, these addresses are referenced and the data is Alternatively, one screen may be recorded in sequence as one pixel column, and the addresses of the first pixel and the last pixel may be 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 placed immediately after the last pixel. In this way, even if a recording method is adopted in which the memory N area is not divided into image units but stores a plurality of image data in the order of addresses, access during playback becomes easy.

Furthermore, as in this embodiment, a color filter is provided in order to extract color signals from the single-chip image sensor 3, but if the color arrangement in this color filter is not known, color separation processing cannot be performed during reproduction. In order to understand the color filter arrangement in the still video camera used, the color filter arrangement as shown in Fig. 5 (R, G, B filters) and Fig. 6 (green, magenta, cyan, yellow filter) is shown. The minimum unit (or code that can be used to refer to the filter array) is stored in memory in correspondence with each screen, and during playback, the color filter array of the still video camera that was shot is read from the memory 6, and the colors are displayed according to this array. Allow the heat treatment to take place. If data indicating the color filter arrangement is stored in the memory 6 in this way, even if there are still video cameras with different color filter arrangements, the playback device will be able to store this data. This makes it possible to use a common playback device for multiple types of still video cameras with different filter arrangements.

In addition, white balance is generally adjusted in video cameras, but the still video camera of this example records in the memory 6 without performing such white balance adjustment, so it is necessary to adjust white balance on the playback device side. There is. For this reason, the information necessary for adjustment includes, for example, the color temperature of the subject detected by the sensor, or, if the camera is equipped with a sensor that supports the three primary colors of RGB, the signal level of each RGB color and the deviation from the reference level. This information is recorded in a memory 6 at the same time as photographing, and is read into this information on the playback device side so that white balance adjustment can be performed satisfactorily.

In addition, the photographing conditions to be stored in the memory 6 along with the photographing include, for example, the spectral characteristics of the color filter, the number of pixels (total number of pixels, effective number of pixels) of the image sensor 3, the spectral characteristics of the infrared cut filter, the optical Spectral characteristics of the system, imaging time,
Examples include dates.

Here, for the spectral characteristics of the infrared cut filter and color filter, instead of directly recording the characteristic values, the manufacturer's name, model number, thickness, etc. may be recorded. Furthermore, when storing the spectral characteristics of an optical system such as an optical lens or a crystal plate, the spectral characteristics recorded in the memory may be read out and the three primary color signals may be corrected based on the spectral characteristics. Furthermore, based on the data of the shooting date and time corresponding to the image recorded in the memory, the predicted shooting environment may be reflected in the color reproduction, for example, by increasing the red of the reproduced image in the evening. 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 the shooting location and weather may be recorded in the memory in association with the image by the photographer's operation.

On the other hand, in addition to recording the photographing conditions in the memory together with the image data as described above, it is also possible to carry out more efficient signal processing or save storage capacity by taking the following measures when recording the image data. desirable.

Normally, when image data is recorded in a memory, it is recorded in pixels as shown in FIG.
3 pixels each for green G filter and 3 pixels for blue B filter
If pixels are collectively recorded in memory for each primary color, a correlation will emerge between adjacent pixels of the same color, making compression processing more efficient.

In addition, in a normal image sensor, the number of pixels for optical black (OB), which is the black reference, is 40 x 500 (20K).
However, it is not necessary to record everything, so for example, you can record only one OBB pixel per scanning line, or record only one OBB pixel in one image, and store it in memory. It is also possible to save capacity. Here, when recording only one OBB pixel for one scanning line, record one OBB pixel from one scanning line.
Or, take the average of OBB pixels (about 40 pixels) in one scanning line and use the average value as OB pixel data for each scanning line, and one OB pixel data per image. If you want to record the differences, take the overall average and record it. Furthermore, when the signal level variation of OBB pixels is large,
It is also possible to record pixels, and when the variation is small, to record one pixel for each image.

<Effects of the Invention> As explained above, according to the present invention, in a still video camera configured to record a digital image signal in a memory, since the shooting conditions are recorded in the memory together with the image, the camera side does not have to be omitted. When a signal processing circuit is provided on the playback device for playback, the desired signal processing can be performed even if devices with different shooting conditions such as color filters are mixed, simplifying the circuit configuration of the still video camera. This has the effect of being able to support playback of recorded images under different shooting conditions.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a still video camera in an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a playback device in the same embodiment, and FIG. 3 shows the conversion characteristics of an A/D converter. Figure 4 is a diagram showing the characteristics when recording the recording location of image data, and Figures 5 and 6 are color filter distribution diagrams showing the minimum unit when recording the type of color filter. , Fig. 7 is a diagram showing the recording area of photographing conditions in the memory, Fig. 8 is a recording processing state diagram showing the recording state for each filter color, and Fig. 9 shows a conventional example of a digital recording type still video camera. FIG. 10 is a block diagram showing a conventional example of an analog recording type still video camera.

Claims (1)

[Claims] A still configured to convert an optical image signal of a subject obtained by an optical lens into an electrical image signal by an image sensor, and further store the digital image signal obtained by A/D conversion by an A/D converter in a memory. 1. A still video camera characterized in that the video camera is configured to record photographing conditions in the memory together with recording digital image signals.