JP2934074B2 - Electronic still camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic still camera which converts an image signal into a digital signal and records the digital signal.

[0002]

2. Description of the Related Art In addition to an electronic still camera using a magnetic sheet as a recording medium, recently, an electronic still camera using a memory card having a built-in IC memory as a recording medium has been provided. In an electronic still camera using a magnetic sheet as a recording medium, it is necessary to rotate the magnetic sheet at a high speed during recording / reproducing. On the other hand, when a memory card is used as a recording medium, it is necessary to rotate the magnetic sheet with the memory card during recording / reproducing. It is only necessary to electrically exchange image data, which not only simplifies the configuration of the camera and the playback device, but also improves the image quality.

[0003] In an electronic still camera for performing color imaging, it is necessary to separate image signals output in chronological order from a solid-state imaging device for each color, and then perform correction processing such as white balance adjustment and gamma correction. After these correction processes, the image signal is usually converted into a luminance signal and a color difference signal (or color signal). Further, when recording image data on a memory card, it is necessary to convert an analog image signal into a digital image signal, but until now, before performing color separation or after performing color separation, the correction processing is performed. The A / D conversion was performed before the execution.

[0004]

As described above, in the A / D converter that performs A / D conversion before performing color separation, an A / D converter is used to A / D convert a series of image signals in time series. Although there is an advantage that only one is required, all subsequent correction processing also requires digital processing, and input data for white balance adjustment and gamma correction must be prepared as digital values, resulting in a circuit configuration It cannot be simplified. In addition, considering the signal band of the analog image signal output from the CCD image sensor, the analog image signal is digitally converted by a 10-bit or more A / D converter in order to perform white balance adjustment and gamma correction digitally. And the A / D converter itself becomes quite expensive. After color separation, A /
In the case of performing D conversion, an A / D converter is required for each color channel, which is disadvantageous in that the circuit configuration is complicated and the cost is reduced.

The present invention has been made in view of the above background, and simplifies the circuit configuration by performing analog processing for correction processing such as white balance adjustment and gamma correction, and enabling A / D conversion on a single channel. It is an object to provide an electronic still camera.

[0006]

In order to achieve the above object, the present invention provides an image signal obtained in time series from a solid-state image sensor.
Signal on the front of the solid-state image sensor.
Based on the sampling pulse generated corresponding to the
To separate the image signal for each color
Correct processing is performed, and the image signal after the correction processing is
It is configured to perform resampling processing to return to the image signal.
It is. Image signal after correction processing by resampling processing
Signal is converted back to a time-series image signal, which is
Digitally converted to digital image signal by D converter
It is.

[0007] The A / D converter outputs a digital image signal which is a series in time series, and performs digital signal processing for generating a luminance signal and a color difference signal based on the digital image signal. And when the digital signal processing, the time series of the digital image signal, the line identification of the color information corresponding to the filter array of color filters incorporated in front of the solid-state image sensor
After the color information is confirmed, the digital image signal is stored in the memory.
Digitally recorded. In the identification of the color information, according to the present invention, the image signal from the solid-state imaging device is separated for each color.
Sampling pulses used to come, or correction
Used later to return the image signal to a time-series image signal again.
The color obtained by delaying the resampling pulse
An identification pulse is used. This eliminates the need for a delay circuit or counter, which was conventionally required to generate a color identification pulse from a horizontal synchronization signal or horizontal drive pulse, and also allows the phase of the color identification signal to fluctuate due to the effects of ambient temperature. Thus, the color information can be reliably identified.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 schematically showing the electric configuration of an electronic still camera according to the present invention, a subject image is formed on a photoelectric surface of a CCD image sensor 2 by a lens 3. C
A color filter 4 is incorporated in the front of the CD image sensor 2. As shown in FIG. 2, the color filter 4 has a red transmission filter 4R, a green transmission filter 4G, and a blue transmission filter 4B arranged in correspondence with the pixel arrangement of the CCD image sensor 2. The green transmission filter 4G is a CCD image sensor. The red transmission filter 4R and the blue transmission filter 4B are arranged in a stripe pattern in the vertical scanning direction of the sensor 2 and in a checkered pattern for each row. The CCD image sensor 2 receives drive pulses such as a field shift pulse, a vertical transfer pulse, and a horizontal transfer pulse supplied from the CCD driver 5 and converts an optical image formed on the photoelectric surface into an electric image signal. Output.

The image signals output as analog quantities from the CCD image sensor 2 are output in the order of horizontal scanning under the filter arrangement of FIG. 2, so that the green image data is output as shown in FIG. G ₁ , red image data R
₁ , green image data G ₂ , blue image data B ₁ , green image data G ₃ , red image data R ₂ ,... An image signal composed of these image data is separated by a preamplifier and a color separation circuit 6 into image data for each color. For this color separation, the timing generator 8 outputs the image data G _n , R _n , B _n shown in FIG.
Is supplied to the preamplifier and the color separation circuit 6 in synchronism with the readout cycle.

The image data separated for each color by the preamplifier and the color separation circuit 6 is processed by an analog processing circuit 9.
Performs well-known white balance adjustment and gamma correction. For this reason, a photometric circuit 9a and a white balance (WB) detecting circuit 9b are connected to the analog processing circuit 9, from which analog data for correction is input. These correction processes are performed for each color channel by analog processing, and the corrected image data is supplied to the resampling circuit 10. The resampling circuit 10 receives image data separated for each color as shown in FIG. 3 and outputs them as a series of time-series image signals as shown in FIG. Therefore, the resampling pulse shown by the timing pulse generator 8 is supplied to the resampling circuit 10. The resampling pulse is generated in synchronization with the sampling pulse supplied to the preamplifier and the color separation circuit 6 and at a timing in which the processing time in the analog processing circuit 9 is considered.
Note that the image data for each color channel G _n, R _n, B _n
Is a resampling circuit 1 so that false color noise does not occur.
Although the color filters 4 are arranged in time series again in the order of the filter arrangement of the color filters 4, the arrangement order of the image data G _n , R _n , and B _n by the resampling circuit 10 does not necessarily have to be the filter arrangement of the color filters 4. Is also good.

The image signal that has been time-serialized again by the resampling circuit 10 is digitally converted by the A / D converter 14. Image signal after digital conversion is inputted to the digital processing circuit 15, the luminance signal is produced by the image data G _n, also the image data G _n and the image data R _n, the color difference signals from the image data B _n is produced. In the process of producing the color difference signal, a series of digitized image data G _n , R
It is necessary to accurately identify what color each of _n and _Bn corresponds to the image data. For this reason, the resampling pulse supplied to the resampling circuit 10 is also supplied to the digital processing circuit 15.

The digital processing circuit 15 delays the resampling pulse by ΔT, and uses the pulse used when resampling the red image data R _n as a red identification pulse. Since the delay time ΔT is determined according to the conversion processing time of the A / D converter 14,
It is possible to reliably associate the color information of the image data at the time of resampling with the color information of the image data at the time of digital processing. Further, since the resampling pulse is synchronized with the sampling pulse supplied to the preamplifier and the color separation circuit 6, even if the clock pulse generation cycle of the timing pulse generator 8 slightly fluctuates due to the influence of the ambient temperature, the resampling pulse is generated. Since the resampling pulse fluctuates in exactly the same manner, the color information of the image data can be accurately collated by using the red identification pulse obtained as described above. In order to generate the red identification pulse from the sampling pulse supplied to the preamplifier and the color separation circuit 6 instead of the resampling pulse, the required processing time in the analog processing circuit 9 and the resampling circuit 10 is further reduced by the delay time. What is necessary is just to add to (DELTA) T.

The digital processing circuit 15 confirms that the color information of the image data is appropriate, and the luminance signal and the color difference signal obtained by the digital processing are input to the memory controller 16 as time-series digital image signals. The memory controller 16 temporarily stores the digital image signal as image data for each pixel in the frame memory 17.
Write to. Thereafter, the memory controller 16 reads out the image data from the frame memory 17, performs a data compression process or an encoding process in response to a command from the system controller 18, writes the image data in a predetermined address area of the memory card 20, and writes one frame. Recording of the still image for the minute is completed. If the color information is not properly collated by the digital processing circuit 15, a warning is displayed after the data is written to the frame memory 17 to urge re-recording, or the image data written to the frame memory 17. Prompts you to select whether to delete or save.

According to the above circuit configuration, the image signal obtained from the CCD image sensor 2 by one recording operation is separated into analog image signals for each color by the preamplifier and the color separation circuit 6, and then the analog processing circuit At 9, analog correction processing such as white balance adjustment and gamma correction is performed. Therefore, the analog processing circuit 9 includes a photometry circuit 9a and a WB detection circuit 9b which are conventionally used.
All you have to do is input the analog data from. The analog image signal corrected for each color channel by the analog processing circuit 9 is again converted to a series of time-series image signals by the resampling circuit 10, and then digitally converted by the A / D converter 14. This eliminates the need for providing the A / D converter 14 for each color channel, and simplifies the circuit configuration. Further, since the compression processing of the signal band can be easily performed by the analog processing circuit 9, A
The / D converter 14 has a generally widely used 8
Bits can be used, and costs can be kept low.

The digital image signal from the A / D converter 14 is converted by a digital processing circuit 15 into an image signal of a predetermined format consisting of a luminance signal and a color difference signal. At this time, the digital processing circuit 15 delays the resampling pulse by the time ΔT required for the digital conversion process, and uses the resampling pulse used when resampling the red image data R _n as a red discrimination pulse. identification pulse and checks whether consistent with the phase of the red image data R _n in the digital image signal. By this confirmation, the digital processing circuit 15
Thus, a luminance signal and a color difference signal can be accurately generated, and appropriate image data can be written in the memory card 20.

Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to an electronic still camera that converts image data into a luminance signal and a color difference signal and records the image data. The present invention can also be applied to a case where the three-color image data is recorded as it is. In matching and checking the color information, a blue identification pulse may be used instead of the red identification pulse, and the filter arrangement of the color filter 4 is not limited to that shown in FIG.

[0017]

As described above, according to the electronic still camera of the present invention, the image signals output in time series are separated for each color, and the analog correction processing is performed. A / D conversion is performed by converting the image signal into a simple image signal.
There is no need to provide a converter, and the circuit configuration can be simplified. Further, based on the sampling pulse used for color separation of the time-series image signal or the re-sampling pulse used in the re-sampling processing for converting the image signal separated for each color into a time-series image signal, Since the color information is identified, the color identification can be performed more reliably and the circuit configuration can be simplified as compared with the conventional method of performing color identification by delaying the horizontal synchronization signal etc. in time, This greatly contributes to the cost reduction of electronic still cameras.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an electronic still camera using the present invention.

FIG. 2 is a schematic diagram showing an example of a filter array used in the electronic still camera of the present invention.

FIG. 3 is a time chart showing a form of image data output from some circuit blocks shown in FIG. 1;

[Explanation of symbols]

 2 CCD image sensor 4 Color filter 6 Preamplifier and color separation circuit 8 Timing pulse generator 9 Analog processing circuit 10 Resampling circuit 14 A / D converter 15 Digital processing circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-274588 (JP, A) JP-A-1-190190 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 9/64-9/898 H04N 9/04-9/097

Claims (1)

(57) [Claims] 1. A solid-state imaging device that photoelectrically converts an optically formed image and outputs it as a time-series image signal, and a filter arrangement of a color filter built in a front surface of the solid-state imaging device. Based on the generated sampling pulse
Can, a color separating means for outputting the image signals being output time-sequentially separated into the image signals of each color, and a signal correction means performs correction processing on each of the separated image signals for each color, Resampling generated corresponding to the filter array
Resampling means for converting an image signal for each color after correction processing into a time-series image signal based on a sampling pulse , an A / D converter for digitally converting the image signal from the resampling means,
Color sense that delays any of the sampling pulses for a certain time
Digit obtained from the A / D converter by another pulse
Color identification means for identifying the color information of the
The digital image after the color information has been identified by the identification means
An electronic still camera, comprising: recording means for digitally recording an image signal in a memory .