JPH0564225A - Electronic still camera - Google Patents

Abstract

PURPOSE:To simplify the circuit configuration of an electronic still camera by digitizing a picture signal and recording it. CONSTITUTION:A preamplifier and color separation circuit 6 separates a picture signal outputted by a time group from a CCD image sensor 2 every color. White balance adjustment and a gamma correction are performed for the picture signal separated every color in an analog processing circuit 9. After the picture signal separated every color is again converted into the picture signal of the time series by a resampling circuit 10, the signal is digitized by an A/D converter 14. In a digital processing circuit 15, a resampling pulse supplied to a resampling circuit 12 is supplied and is used for the discrimination of color information of the time series picture signal.

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 it.

[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 an IC memory as a recording medium has been provided. In an electronic still camera that uses a magnetic sheet as a recording medium, it is necessary to rotate the magnetic sheet at a high speed during recording / playback, whereas in a device that uses a memory card as the recording medium, the recording / playback between the memory card and the memory card is performed. It is only necessary to electrically exchange the image data, and not only the structure of the camera and the reproducing device can be simplified, but also the image quality can be improved.

By the way, in an electronic still camera for performing color image pickup, it is necessary to separate the image signals output from the solid-state image pickup device in time series for each color, and then perform correction processing such as white balance adjustment and gamma correction. After performing these correction processes, the image signal is usually converted into a luminance signal and a color difference signal (or a color signal). In addition, when recording image data in a memory card, it is necessary to convert an analog image signal into a digital image signal. Up to now, the correction processing is performed before color separation or after color separation. A / D conversion was performed before the conversion.

[0004]

In the case of performing A / D conversion before performing color separation as described above, since A / D conversion is performed on a series of image signals in time series, an A / D converter is used. 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. Moreover, considering the signal band of the analog image signal output from the CCD image sensor, in order to digitally process white balance adjustment and gamma correction, the analog image signal is digitally converted by an A / D converter of 10 bits or more. Need, and the A / D converter itself is rather expensive. Also, after color separation, A /
In the case of D conversion, an A / D converter is required for each color channel, which again complicates the circuit configuration and is disadvantageous in achieving low cost.

The present invention has been made in consideration of the above background, and the correction processing such as white balance adjustment and gamma correction is analog-processed, and single-channel A / D conversion is possible to simplify the circuit configuration. An object is to provide an electronic still camera.

[0006]

In order to achieve the above object, the present invention provides a solid-state image sensor for photoelectrically converting an optically formed image and outputting it as a time-series image signal, and a solid-state image sensor. The color separation means for performing sampling corresponding to the filter array of the color filter incorporated in the front surface of the color filter, separating the image signals output in time series into image signals for each color and outputting the image signals, and for each color. A signal correction unit that performs a correction process on each of the separated image signals, a resampling unit that returns the image signal for each color after the correction process to a time-series image signal, and an output signal from the resampling unit is digital. An A / D converter for conversion is used.

Further, according to the above configuration, the A / D converter outputs a series of digital image signals in time series, and the digital signal processing for producing a luminance signal and a color difference signal is performed based on the digital image signals. At the time of this digital signal processing, for time-series digital image signals, it is desirable to identify the color information corresponding to the filter array of the color filter incorporated in the front surface of the solid-state image sensor, but in identifying this color information, In the present invention, the sampling pulse used in the color separation means or the resampling pulse used in the resampling means is used. This eliminates the need for delay circuits and counters that were required in the past to generate the color identification signal from the horizontal sync signal and horizontal drive pulse, and the phase of the color identification signal fluctuates due to the effects of ambient temperature. In addition, it is possible to reliably identify the color information.

[0008]

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

The image signals output from the CCD image sensor 2 as analog amounts 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 , ... The image signal composed of these image data is separated into image data for each color by the preamplifier and color separation circuit 6. For this color separation, the timing generator 8 causes the image data G _n , R _n , B _n shown in FIG.
The sampling pulse synchronized with the read cycle of is supplied to the preamplifier and color separation circuit 6.

For the image data separated for each color by the preamplifier and color separation circuit 6, the analog processing circuit 9
Performs well-known white balance adjustment and gamma correction. Therefore, the photometric circuit 9a and the white balance (WB) detection circuit 9b are connected to the analog processing circuit 9, and analog data for correction is input from these circuits. These correction processes are performed for each color channel by analog processing, and the corrected image data are supplied to the resampling circuit 10. The resampling circuit 10 receives the image data separated for each color as shown in FIG. 3, and outputs these as a series of time-series image signals as shown in FIG. Therefore, the resampling circuit 10 is supplied with the resampling pulse shown from the timing pulse generator 8. The resampling pulse is generated in synchronization with the sampling pulse supplied to the preamplifier and color separation circuit 6 and at a timing considering the processing time in the analog processing circuit 9.
The image data G _n , R _n , B _n for each color channel
Is a resampling circuit 1 so that false color noise does not occur.
0 is again arranged in time series in the order of the filter array of the color filter 4, but the resampling circuit 10 does not necessarily have to arrange the image data G _n , R _n , B _n in the filter array of the color filter 4. Good.

The image signal that has been time-series 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 this color difference signal, a series of digitized image data G _n , R
It is necessary to accurately identify what color each of _n and B _n corresponds to image data. Therefore, 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 the red discrimination 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 period of the timing pulse generator 8 fluctuates to some extent due to the influence of the ambient temperature, the resampling pulse is regarded as the sampling pulse. Since the resampling pulse changes 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 addition, in order to generate the red color discrimination pulse from the sampling pulse supplied to the preamplifier and the color separation circuit 6 instead of the resampling pulse, the processing time required in the analog processing circuit 9 and the resampling circuit 10 is set to the delay time. It may be added to ΔT.

It is confirmed by the digital processing circuit 15 that the color information of the image data is proper, and the luminance signal and the color difference signals obtained by the digital processing are input to the memory controller 16 as time series digital image signals. The memory controller 16 temporarily uses the digital image signal as image data for each pixel to create a frame memory 17
Write in. After that, the memory controller 16 reads the image data from the frame memory 17, receives a command from the system controller 18 and performs data compression processing and encoding processing, and writes the image data in a predetermined address area of the memory card 20 for one frame. Recording of the minute still image ends. When the color information is not properly collated by the digital processing circuit 15, a warning is displayed after the data is written in the frame memory 17 to prompt re-recording or the image data written in the frame memory 17 is displayed. Prompt the operation 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 the 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 the photometry circuit 9a and the WB detection circuit 9b which have been 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 converted again into a series of time-series image signals by the resampling circuit 10, and then digitally converted by the A / D converter 14. As a result, it is not necessary to provide the A / D converter 14 for each color channel, and the circuit configuration is simplified. Further, since the analog processing circuit 9 can easily perform the compression processing of the signal band, A
The / D converter 14 is generally widely used 8
Bits can be used, and cost 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 composed 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 the red image data R _n is resampled as a red identification 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
In this case, the luminance signal and the color difference signal can be accurately generated, and proper image data can be written in the memory card 20.

The present invention has been described above with reference to the illustrated embodiment, but the present invention is not limited to an electronic still camera for converting image data into a luminance signal and a color difference signal and recording the same. For example, R, G, B It is also possible to apply to the one that directly records the three-color image data. Further, in checking and confirming the color information, the blue identification pulse may be used instead of the red identification pulse, and the filter array 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 analog correction processing is performed, and then the resampling means again performs time series. Since it is configured to perform A / D conversion with various image signals, A / D conversion is performed for each color channel.
It is not necessary to provide a converter, and the circuit configuration can be simplified. Further, the image signal based on the sampling pulse used when color-separating the time-series image signal or the resampling pulse used at the resampling process for converting the image signal separated for each color into the time-series image signal. Since the color information is identified, compared to the conventional method of performing color identification by delaying the horizontal synchronizing signal and the like in time, reliable color identification is possible and the circuit configuration is simplified. It greatly contributes to the cost reduction of electronic still cameras.

[Brief description of 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 view showing an example of a filter array used in the electronic still camera of the present invention.

FIG. 3 is a time chart showing an aspect of image data output from some circuit blocks shown in FIG.

[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

Claims (2)

[Claims] 1. A solid-state image sensor for photoelectrically converting an image formed optically and outputting it as a time-series image signal, and a filter array of color filters incorporated in the front surface of the solid-state image sensor. A color separation unit that performs sampling and separates and outputs the image signals that are output in time series into image signals for each color, and a signal correction unit that performs correction processing on each of the image signals separated for each color. And a resampling means for returning the corrected image signal for each color to a time-series image signal, and an A / D converter for digitally converting the output signal from the resampling means. Electronic still camera. 2. A solid-state image sensor for photoelectrically converting an image formed optically and outputting it as a time-series image signal, and a filter array of color filters incorporated in the front surface of the solid-state image sensor. Color separation means for separating and outputting the image signals output in time series into image signals for each color based on the generated sampling pulse, and correction processing for each of the image signals separated for each color. A signal correcting means for performing the correction, a resampling means for returning the image signal for each color after the correction processing to a time series image signal based on the resampling pulse generated corresponding to the filter array, and the resampling means. A / D converter for digitally converting the image signal of the above, and a digital converter obtained from the A / D converter in synchronization with the sampling pulse or the resampling pulse. An electronic still camera, comprising: a color identification unit for identifying color information of the image signal.