JPH04319893A - Digital electronic still camera and its operating method - Google Patents

Abstract

PURPOSE:To enhance the resolution, while holding the interchangeability with a conventional electronic still camera by thinning out luminance image data and color image data, respectively and recording the image data in a recording medium. CONSTITUTION:A CCD 12 for outputting an analog video signal for showing an image of an object to be photographed is an element consisting of, for instance, vertical 488 picture elements and horizontal 1536 picture elements and has about 800,000 picture elements. Also, this camera is provided with thinning-out circuits 20, 21 for thinning out luminance picture element data Y and color image data Cb, Cr to image data of a prescribed number of picture elements. In such a state, data of a 800,000-picture element portion obtained from this CCD 12 are thinned out so as to become data of a 400,000-picture element portion by the thinning-out circuits 20, 21. Also, all these data are given to a memory card 23, and all the data of the 400,000-picture element portion are recorded in the memory card 23. Accordingly, many data of the part in which data of a frequency component of a high band is cut are obtained and an image of high resolution is obtained.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a digital electronic still camera and method of operating the same.

0002

2. Description of the Related Art Current digital electronic still cameras use a CCD with approximately 400,000 pixels as a means for photographing a subject. The analog video signal obtained from this CCD is converted into digital image data, subjected to Y/C processing and data compression, and recorded on a recording medium such as a memory card.

0003

[Problems to be Solved by the Invention] A CCD with 400,000 pixels cannot be said to have a sufficiently high resolution. Moreover, the imaging lens
Since high frequency components are reduced due to the influence of optical filters, the resolution is further reduced.

[0004] In recent years, the number of pixels in CCDs has increased, and CCDs with high resolutions of 800,000 pixels or more have become available. Therefore, in order to obtain high-resolution images, 80
It is conceivable to use a CCD with about 10,000 pixels.

However, if the number of pixels of the CCD is increased from 400,000 pixels to 800,000 pixels, 800,000 pixels of Y/C pixel data will be obtained, so the number of frames recorded on the memory card will be reduced. Problems arise, such as the capacity of the display frame memory being reduced to 1/2, and the capacity of the frame memory for the display system being twice that of the conventional one, making it impossible to maintain compatibility with conventional digital electronic still cameras.

An object of the present invention is to enable high resolution while maintaining compatibility with conventional electronic still cameras.

[0007]

[Means for Solving the Problems] The present invention performs Y/C processing and data compression processing on image data obtained from a solid-state electronic image sensor having a predetermined number of pixels in the vertical and horizontal directions, and records the data on a recording medium. In a digital electronic still camera, a single-chip color solid-state electronic image sensor having a horizontal pixel number that is an integer multiple of the above predetermined horizontal pixel number and a vertical pixel number that is the same as the above-mentioned predetermined vertical pixel number; A Y/C processing means that generates brightness image data and color image data from image data obtained from a solid-state electronic image sensor, each of the brightness image data and color image data obtained from the Y/C processing means is horizontally fraction of an integer
a thinning circuit for thinning out the data, a means for data compressing the luminance image data and color image data obtained from the thinning circuit;
The present invention is also characterized by comprising means for recording compressed image data on a recording medium.

[0008] The operating method of the digital electronic still camera according to the present invention provides Y/
In a digital electronic still camera that performs C processing and data compression processing and records on a recording medium, the number of horizontal pixels is an integral multiple of the predetermined number of horizontal pixels, and the number of vertical pixels is the same as the predetermined number of vertical pixels. A single-chip color solid-state electronic imaging device is provided, and brightness image data and color image data are generated from image data obtained from the single-chip color solid-state electronic imaging device, and each of the generated brightness image data and color image data is 1/1 of the above integer in the horizontal direction about
The image data obtained by the above-mentioned thinning process is compressed, and the compressed image data is recorded on a recording medium.

The present invention is also applicable to digital electronic still cameras that perform monochrome photography. This invention is
In a digital electronic still camera capable of monochrome and color photography in which image data obtained from a solid-state electronic image sensor having a predetermined number of pixels in the vertical and horizontal directions is subjected to data compression processing and recorded on a recording medium, the predetermined horizontal direction is A solid-state electronic image sensor having a horizontal pixel number that is an integral multiple of the number of pixels and a vertical pixel number that is the same as the predetermined vertical pixel number, and image data obtained from the solid-state electronic image sensor is horizontally divided by the above-mentioned integer. a thinning circuit for thinning out data, a means for compressing image data obtained from the thinning circuit;
The present invention is also characterized by comprising means for recording compressed image data on a recording medium.

0010

[Operation] A digital electronic still that performs Y/C processing and data compression processing on image data obtained from a solid-state electronic image sensor having a predetermined number of pixels in the vertical and horizontal directions (for example, 400,000 pixels) and records it on a recording medium. - According to the present invention, the camera has a horizontal pixel number that is an integral multiple (for example, twice) of the predetermined horizontal pixel number and a vertical pixel number that is the same as the predetermined vertical pixel number (for example, 80
A single-plate color solid-state electronic image sensor (of 10,000 pixels) is provided.

Luminance image data and color image data are generated from image data obtained from the single-plate color solid-state electronic image sensor. The generated luminance image data and color image data are each thinned out in the horizontal direction by a fraction of the above-mentioned integer (for example, 1/2). Then, the image data obtained by the above thinning process is compressed,
The compressed image data is recorded on a recording medium (for example, a memory card).

[0012] Although a solid-state electronic image pickup device is used in which the number of pixels in the horizontal direction is an integer multiple of that of conventional devices, the image data obtained from it is thinned out to an integer fraction, so that the final image obtained is The number of data pixels is the same as the conventional one. Therefore, it is possible to record the same number of frames of images on a recording medium as with a conventional digital electronic still camera, and it is also possible to use a display memory with the same capacity as the conventional one.

[0013]

[Effects of the Invention] As described above, it is possible to record the same number of frames of images on a recording medium as a conventional digital electronic still camera, and it is also possible to use a display memory with the same capacity as the conventional digital electronic still camera. Therefore, the digital electronic still camera according to the present invention can maintain compatibility with conventional cameras.

Moreover, since the present invention uses a solid-state electronic image pickup device whose number of pixels in the horizontal direction is an integral multiple of that of the conventional device, the image data obtained is more sensitive to high frequency regions than the image data obtained from the conventional device. has a larger amount of information. Therefore, higher quality images can be realized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, and is a block diagram showing the electrical configuration of a digital electronic still camera. FIG. 2 schematically shows the state of pixel data in the circuit shown in FIG.

The digital electronic still camera 1 shown in FIG. 1 is connected to a memory card 23 for recording data of a photographed subject image and a monitor 25 for visually displaying the photographed subject image.

In the digital electronic still camera 1, the entire operation of the camera is supervised by a controller 15 under the control of a control device 10.

The digital electronic still camera 1 includes an imaging lens 11, a CCD 12 that outputs an analog video signal representing an object image, a color balance adjustment for the analog video signal,
A signal processing circuit 13 that performs processing including gamma correction, etc., and an A/D that converts analog video signals into digital image data.
A conversion circuit 14, a frame memory 16 that temporarily stores digital image data, a Y/C processing circuit 17 that creates luminance image data Y, color image data Cb and Cr from the digital image data, and a low frequency component that removes high frequency components. Pass filters 18 and 19, thinning circuits 20 and 21 that thin out the luminance image data Y and color image data Cb and Cr into image data of a predetermined number of pixels, data compression/
It includes a compression/decompression circuit 22 that performs expansion, encoding/decoding, and a reproduction processing circuit 24 that visually displays a subject image on a monitor 25.

The object image is captured by the CCD by the imaging lens 11.
The image is formed on 12 planes.

As shown at the left end of FIG. 2, the CCD 12 is an element of 488 pixels vertically and 1536 pixels horizontally, and has approximately 80 pixels.
It has 10,000 pixels. CCD12 has R (red),
G (green) and B (blue) pixels are arranged in a predetermined array, and an analog video signal representing a subject image is output from the CCD 12 in response to depression of a shutter (not shown).

The analog video signal output from the CCD 12 is given to a signal processing circuit 13. Signal processing circuit 13
includes a color balance circuit and a gamma correction circuit,
Color balance adjustment and gamma correction are applied to the input analog video signal. In particular, gamma correction of the video signal narrows the dynamic range, so the next stage A/
The number of bits of the D conversion circuit 14 can be reduced.

The analog video signal output from the signal processing circuit 13 is applied to an A/D conversion circuit 14 and converted into digital image data. Digital image data is provided to frame memory 16 by controller 15 and temporarily stored. This frame memory 16 stores image data of 800,000 pixels.

The image data once stored in the frame memory 16 is read out by the controller 15 and given to the Y/C processing circuit 17, and as shown in the center of FIG. color image data C
is generated.

The luminance image data Y is passed through the low-pass filter 18
The high frequency components are removed by , and the resulting signal is applied to the thinning circuit 20 . The decimation circuit 20 decimates the luminance image data Y to data of about 400,000 pixels as shown on the right side of FIG. The thinned out luminance image data Y is stored in the frame memory 16 again.

The color image data Cr and Cb are supplied to a thinning circuit 21 after high frequency components are removed by a low-pass filter 19 . Figure 2 by the thinning circuit 21
As shown at the right end of , the color image data Cr and Cb are each thinned out to about 200,000 pixels. The thinned out color image data Cr and Cb are each temporarily stored in the frame memory 16.

The thinning circuits 20 and 21 thin out every other piece of luminance image data and color image data under the control of a clock signal.

In this way, approximately 400,000 pixel data after being thinned out is stored in the frame memory 16.

Luminance image data Y and color image data Cr and Cb stored in the frame memory 16
is applied to the compression/expansion circuit 22. These image data Y, Cr and Cb are subjected to DCT (Discrete Cosine Tr) in the compression/expansion circuit 22.
ansform) and is provided again to the frame memory 16 for storage. If necessary, this compression process is performed multiple times, such as applying compression process again to the once compressed data.

The DCT-transformed luminance image data Y and color image data Cr and Cb are read out from the frame memory 16 again, applied to the compression/expansion circuit, and subjected to Huffman encoding. Each piece of data compressed and encoded in this way is given to the memory card 23 and recorded in a predetermined area of the memory card 23. The memory card 23 can store the same number of images as a conventional camera with a 400,000 pixel CCD.

The camera shown in FIG. 1 can read data recorded on the memory card 23 and reproduce images. For this purpose, a reproduction processing circuit 24 and a monitor 25 are used.
It is included.

Data recorded on the memory card 23 is read out and applied to the compression/expansion circuit 22 to be decoded. The decoded data is stored in frame memory 1.
6 is temporarily stored. The decoded data is read out from the frame memory 16 and given again to the compression/expansion circuit 22 where it is subjected to inverse DCT transformation.

The inverse DCT-converted data is supplied to the reproduction processing circuit 24, where it is converted into an analog video signal and visually displayed on the monitor 25. The reproduction processing circuit 24 includes a frame memory for storing reproduction image data, a D/A conversion circuit, and the like. This frame memory is conventional 4
A camera with the same capacity as a camera with a 00,000 pixel CCD can be used.

Y of conventional digital electronic still camera
The /C processing circuit also has a low pass filter for the generated luminance image data Y and color image data Cr and Cb. This conventional low-pass filter mainly uses C
Frequency component of sampling pulse used to read image data from CD (fs/2=14.3/2MH
z) (carrier frequency).

In the embodiment of this invention, the CCD 12
A sampling pulse having a frequency of 2 fs, twice that of the conventional one, is used for reading out image data from the image data. Therefore, the low pass filters 18, 19 do not need to be used to remove the carrier signal component as in the conventional filters. As the number of pixels in the horizontal direction of the CCD increases, distortion tends to occur, so low-pass filters 18 and 19 are used only to remove this distortion.
It would be better to use

Therefore, in conventional digital electronic still cameras, high frequency components of image data are considerably cut off by using a low pass filter for carrier removal, but in the embodiment according to the present invention, high frequency components are cut off considerably. Components (particularly components near the conventional carrier frequency) are not cut.

As mentioned above, in conventional digital electronic still cameras, high frequency components are cut off and cannot be recorded, but with the present invention, data representing high frequency components can be recorded, resulting in high resolution and high resolution. Image quality will be improved.

[Brief explanation of drawings]

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

FIG. 2 schematically represents the state of image data in the circuit shown in FIG. 1;

[Explanation of symbols]

12 CCD 14 A/D conversion circuit 15 Controller 16 Control device 20, 21 Thinning circuit 23 Memory card

Claims (3)

[Claims] Claim 1: Y/C for image data obtained from a solid-state electronic image sensor having a predetermined number of pixels in the vertical and horizontal directions.
A digital electronic still camera that performs processing and data compression processing and records on a recording medium, which has a horizontal pixel number that is an integral multiple of the above predetermined horizontal pixel number and a vertical pixel number that is the same as the above predetermined vertical pixel number. A single-plate color solid-state electronic image sensor, a Y/C processing means for generating luminance image data and color image data from image data obtained from the single-plate color solid-state electronic image sensor, and a luminance obtained from the Y/C processing means. A thinning circuit that horizontally thins out each of the image data and the color image data to one fraction of the above-mentioned integer, a means for compressing the luminance image data and the color image data obtained from the thinning circuit, and recording the compressed image data. A digital electronic still camera characterized by comprising means for recording on a medium. 2. Y/C for image data obtained from a solid-state electronic image sensor having a predetermined number of pixels in the vertical and horizontal directions.
A digital electronic still camera that performs processing and data compression processing and records on a recording medium, which has a horizontal pixel number that is an integral multiple of the above predetermined horizontal pixel number and a vertical pixel number that is the same as the above predetermined vertical pixel number. A single-plate color solid-state electronic image sensor is provided, brightness image data and color image data are generated from image data obtained from the single-plate color solid-state electronic image sensor, and each of the generated brightness image data and color image data is A method of operating a digital electronic still camera, which comprises thinning out the image data by a fraction of an integer in the horizontal direction, compressing the image data obtained by the thinning process, and recording the compressed image data on a recording medium. 3. A digital electronic still camera that performs data compression processing on image data obtained from a solid-state electronic image sensor having a predetermined number of pixels in the vertical and horizontal directions and records it on a recording medium, wherein the predetermined number of pixels in the horizontal direction is a solid-state electronic image pickup device having a horizontal pixel count that is an integral multiple of , and a vertical pixel count that is the same as the predetermined vertical pixel count, and thinning the image data obtained from the solid-state electronic image pickup device horizontally to a fraction of the above-mentioned integer. 1. A digital electronic still camera comprising a thinning circuit, means for compressing image data obtained from the thinning circuit, and means for recording the compressed image data on a recording medium.