JPH10126813A - Image pickup device, recording medium and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively evade the deterioration of picture quality to compress the data with high efficiency and to reduce the quantity, of data stored in a still picture file and to be transmitted in a simple constitution by transmitting the color signals outputted from an image pickup element after the data are compressed for every color signal. SOLUTION: A data compression circuit 6 successively fetches the image data to be outputted to a bus BUS and compresses these image data to output them to the BUS. That is, a DCT(discrete cosine transformation) circuit 7 inputs the image data which are successively outputted to the BUS and applies the DCT to the image data in each block. A quantization circuit 8 quantizes the output data of the circuit 7 for each color signal and outputs them. An encoding circuit 9 applies the variable length encoding processing to the output data of the circuit 8 and then outputs them. Then the circuit 6 outputs the output data of the circuit 9 to the BUS.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image pickup apparatus, a recording medium, and an image processing method, and can be applied to, for example, an electronic still camera. The present invention reduces the amount of image data to be transmitted with a simple configuration by compressing and transmitting a color signal output from an image sensor for each color signal.

[0002]

2. Description of the Related Art Conventionally, in an electronic still camera, a video signal is generated from an output signal of an image sensor by a method similar to that of a television camera, and the video signal is selectively captured in response to a user operation. Record on a recording medium. Further, the still image thus captured is used for various image processing in, for example, a personal computer or the like.

[0003] On the premise of this, in this type of electronic still camera, the process of converting to an image signal is omitted, and the output signal of the image sensor is directly recorded on a recording medium.
In some personal computers, a video signal is generated from an output signal of the image sensor.

[0004] In an electronic still camera that performs such a conversion process into a video signal on the personal computer side, the overall configuration can be simplified accordingly.

[0005]

In the method of recording the output signal of the image pickup device as it is on a recording medium, for example, when the image pickup device has 400,000 pixels, one still image file becomes 400 Kbytes. . Therefore, there is a disadvantage that a large-capacity recording medium must be used. Further, even when data is directly input to a computer, there is a disadvantage that data transfer takes time.

If the data amount of such a still image file can be reduced, this kind of disadvantage can be solved.

The present invention has been made in view of the above points, and proposes an imaging apparatus, a recording medium, and an image processing method that can reduce the data amount of a still image file to be transmitted with a simple configuration. It is assumed that.

[0008]

In order to solve the above-mentioned problems, the present invention is applied to an image pickup apparatus, and a plurality of color signals output from an image pickup device are compressed for each color signal and output.

Further, in a recording medium which is applied to a recording medium and records an output signal of an image sensor formed by a plurality of color signals, data is compressed for each color signal and recorded together with identification information of each color signal.

Further, by applying the present invention to an image processing method, a color signal output from an image pickup device is subjected to data compression processing for each color signal and transmitted, and the transmitted color signals are decompressed to generate a video signal of a still image. I do.

By applying the present invention to an image pickup apparatus and compressing a plurality of color signals output from the image pickup device for each color signal,
Data compression can be performed with a large data compression ratio to prevent image quality deterioration.

Further, when the present invention is applied to a recording medium and the respective color signals are compressed and recorded together with the identification information of the respective color signals, on the reproduction side of the recording medium, the expanded color signals are processed in accordance with the identification information. Thus, a video signal of a still image can be generated. At this time, by compressing the data for each color signal, the data amount of the still image file can be reduced and recorded.

Further, by applying the present invention to an image processing method, a color signal output from an image pickup device is subjected to data compression processing for each color signal and transmitted, and the transmitted color signals are decompressed to generate a video signal of a still image. Then, a video signal of a still image can be generated after transmitting the still image file after compressing the data at a large data compression ratio.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an electronic still camera according to an embodiment of the present invention. The electronic still camera 1 forms an image of a subject on an imaging surface of a CCD solid-state imaging device (CCD) 3 by a predetermined optical system 2.

Here, as shown in FIG. 2, the CCD solid-state imaging device 3 has two horizontal and vertical directions.
A predetermined color filter is sequentially and cyclically assigned to each pixel. Here, Ye, Cy, Mg, and G indicate yellow, cyan, magenta, and green, respectively. Thus, the CCD solid-state imaging device 3 can obtain a color still image by performing signal processing on an output signal.

The CCD solid-state imaging device 3 is driven by a predetermined driving circuit and outputs output signals of respective pixels in the order of raster scanning. Further, the CCD solid-state imaging device 3 correlatively double-samples the output signal in a peripheral circuit (not shown) and executes a predetermined signal processing to output the signal. An output signal S1 is output.

A / D conversion circuit (A / D) 4
Converts the output signal of the CCD solid-state imaging device 3 into analog-to-digital conversion and outputs the signal.

The memory 5 captures and holds one screen of image data output from the analog-to-digital conversion circuit 4 in response to a shutter operation by a user. Further, the memory 5 outputs the captured image data to the bus BUS in a predetermined order for each color signal.

That is, the memory 5 first outputs the image data of yellow Ye for one screen, and then outputs the image data of cyan Cy for one screen. Subsequently, the memory 5 outputs the image data of magenta Mg for one screen, and then outputs the green image data for one screen.

At this time, the memory 5 divides one screen by each color signal into 8 × 8 pixel blocks, and outputs image data in units of each block. Further, the memory 5 outputs the image data so as to be continuous in the order of raster scanning in each block.

The data compression circuit 6 sequentially takes in the image data output to the bus BUS, compresses the data, and outputs the compressed image data to the bus BUS. That is, in the data compression circuit 6, a discrete cosine transform circuit (DCT) 7 inputs image data sequentially output to the bus BUS, and performs discrete cosine transform processing for each block. Further, the discrete cosine conversion circuit 7 outputs 8 × 8 coefficient data obtained as a result of the discrete cosine processing in a zigzag scan order.

The quantization circuit 8 quantizes the output data of the discrete cosine transform circuit 7 according to a quantization table set for each color signal and outputs the result. The encoding circuit 9 performs a variable-length encoding process on the output data of the quantization circuit 8 by applying the entropy encoding method, and outputs the data. In the data compression circuit 6, the output data of the encoding circuit 9 is output to the bus BUS, and in this series of data compression processing, image data is compressed for each color signal, thereby effectively preventing image quality deterioration. To improve compression efficiency.

The IC memory card 10 is a card-shaped recording medium containing a nonvolatile memory, and is detachably held by the electronic still camera 1. The IC memory card 10 stores the output data of the encoding circuit 9 output to the bus BUS in a predetermined format as a still image file for each still image.

The central processing unit (CPU) 11 constitutes a control circuit for controlling the operation of the electronic still camera 1 as a whole. That is, the central processing unit 11 controls the operation of the memory 5 in response to the operation of the user, and stores the image data of the still image in the memory 5. Further, the operation of the memory 5 and the data compression circuit 6 is controlled, and the image data held in the memory 5 is compressed by the data compression circuit 6 and recorded on the IC memory card 10.

At this time, the central processing unit 11 outputs a control code, information on an image pickup system, and the like to the IC memory card 10 at a predetermined timing, thereby recording each still image file in the format shown in FIG. That is, the central processing unit 11 attaches a control code indicating the head of the file, a quantization table, and the like to the head of each still image file, and then records information of an imaging system indicating an array of color filters of the CCD solid-state imaging device 3. I do. Thus, the central processing unit 11 can convert the image data recorded on the IC memory card 10 into a still image video signal composed of red, blue, and green color signals with reference to the information of the imaging system. It has been made like that.

The central processing unit 11 records various decoding data common to each image data following the information of the imaging system, and then arranges a color code for identifying each color signal. The encoded data of the corresponding image data is recorded. When the color code and the encoded data are recorded in the IC memory card 10 for yellow, cyan, magenta, and green, the central processing unit 11 adds a control code indicating the end of the image.

FIG. 4 is a block diagram showing an image processing apparatus for processing a still image picked up by the electronic still camera 1 in this way. In the image processing apparatus 20, the IC memory card 10 removed from the electronic still camera 1 is inserted into a predetermined slot and connected to the bus BUS.

In this image processing apparatus 20, the IC memory card 10 is controlled by the central processing unit 21 to sequentially output the stored still image files to the bus BUS. The data decompression circuit 22 sequentially inputs the image data of the still image file output to the bus BUS, decompresses the data, and outputs the data.

That is, in the data decompression circuit 22, the decoding circuit 23 converts the encoded data of the still picture file into the original output data of the quantization circuit 8, and outputs the data to the inverse quantization circuit 24.
Converts the output data of the decoding circuit 23 into the original coefficient data. Inverse discrete cosine conversion circuit (Inverse D
CT) 25 performs inverse discrete cosine transform processing on the coefficient data and outputs image data of 8 × 8 pixels. The data decompression circuit 22 outputs the output data of the inverse discrete cosine conversion circuit 25 to the bus BUS.

The memory 26 holds the output data of the data decompression circuit 22 output to the bus BUS. Further, the stored output data is output to the central processing unit 21 via the bus BUS, and the red, blue, and green image data generated by the arithmetic processing of the central processing unit 21 is stored. Further, it outputs the red, blue and green image data to the CRT controller 27 via the bus BUS.

The central processing unit 21 constitutes a control circuit for controlling the operation of the entire image processing apparatus 20, accesses the IC memory card 10 in response to a user operation, and stores the data in the IC memory card 10. A list of still image files is displayed on the CRT 28. Further, when the user selects a still image file and selects a reproduction mode, the central processing unit 21 reads out the still image file selected by the user from the IC memory card 10 and transfers it to the data decompression circuit 22. Decompress the image data of the image file. Central processing unit 2
1 stores the image data of the decompressed still image file in the memory 26.

Further, the central processing unit 21 sequentially processes the image data of the still image file composed of the yellow, cyan, magenta, and green image data stored in the memory 26 in the arrangement order of the pixels of the CCD solid-state imaging device 3. The image data is read out and subjected to matrix arithmetic processing, whereby the still image composed of the yellow, cyan, magenta, and green image data is converted into a still image composed of video signals composed of red, blue, and green color data.

At this time, the central processing unit 21 operates according to the information of the imaging system added to the head of each still image file.
The digital color signals stored in the memory 26 are sequentially read out in the order in which they are output from the CCD solid-state imaging device 3 in accordance with the color code of each digital color signal, and are subjected to matrix operation processing. Further, the central processing unit 21 executes a matrix operation process corresponding to the color filter of the CCD solid-state imaging device 3 in accordance with the information of the imaging system added to the head of each still image file. The band is expanded and output as compared with the red and blue color signals. As a result, the central processing unit 21
A video signal is generated from a digital color signal data-compressed for each color signal. At this time, a high-resolution video signal is generated with reference to the information of the imaging system added to each digital color signal. ing.

When the central processing unit 21 outputs the digital color signals of red, blue and green by the matrix operation to the bus BUS, the central processing unit 21 also performs operation processing such as knee processing and gamma correction processing. It generates red, blue, and green digital color signals corresponding to video signals output from ordinary video equipment.

The CRT controller 27 inputs the video signal once stored in the memory 26 via the bus BUS,
The CRT 28 is driven by this video signal.

In the above configuration, the electronic still camera 1
, Yellow, cyan,
After the imaging result for one line is output from the arrangement of the color signals of yellow, cyan,..., Then the imaging result for one line is output from the arrangement of the color signals of magenta, green, magenta, green,. Then, the line is sequentially and alternately repeated to output an output signal S1 as an imaging result.

The output signal S1 of the CCD solid-state imaging device 3
Is converted into a continuous digital color signal by the analog-to-digital conversion circuit 4, and then temporarily stored in the memory 5. At this time, the digital color signal is selectively stored in the memory 5 in response to a user's shutter operation, whereby image data of a still image is held in the memory 5.

The image data held in the memory 5 is
The data is output to the data compression circuit 6 for each color data, and is subjected to discrete cosine transform processing, quantization processing, entropy coding processing and data compression in units of 8 × 8 pixels. Will be recorded. Thereby, the output signal of the CCD solid-state imaging device 3 is data-compressed for each color signal.

As described above, in the output signal of the CCD solid-state image pickup device, there is a feature that the correlation between continuous image data is low. On the other hand, if the color signals are combined as described above, a high correlation can be obtained between continuous image data. Accordingly, a high data compression rate can be obtained by performing data compression for each color signal. Further, image quality deterioration due to data compression can be effectively avoided. Incidentally, JPEG (Joint Photographic Coding Experts G) which is a process similar to the data compression process according to this embodiment.
roup), a still image of about 400 Kbytes
Since the data can be compressed to about 00 Kbytes, the same data compression ratio can be obtained in this embodiment, though depending on the setting of the quantum circuit table and the like.

At the time of recording on the IC memory card 10, the image data is added with information on an imaging system consisting of arrangement information of color filters of the CCD solid-state imaging device 3 and a color code consisting of identification information of each color signal. And, in still image units,
Recorded as a still image file.

The IC memory card 10 on which the still image file has been recorded in this manner is removed from the electronic still camera 1 and mounted on the image processing apparatus 20.

When the IC memory card 10 is mounted on the image processing apparatus 20 in this manner, the still image files stored in the IC memory card 10 are accessed by the central processing unit 21 and the list is displayed on the CRT 28. According to this display, the image data of the corresponding still image file is stored in the IC memory card 1 in response to a user operation.
0 is input to the data decompression circuit 22.

Here, the image data is decompressed by a process reverse to that of the data compression circuit 6 in the electronic still camera 1, converted into forward dimensional yellow, cyan, magenta, and green image data and stored in the memory 26. Is stored. Thereafter, the image data held in the memory 26 is sequentially output to the central processing unit 21 in the order of arrangement of each pixel in the CCD solid-state imaging device 3, where it is subjected to matrix operation processing, and the red, blue, and green colors are processed. Converted to color data.

At this time, the color data is arranged in accordance with the information of the imaging system, and CCDs arranged so that a green imaging result can be obtained with a higher resolution than red and blue.
According to the arrangement of the color filters of the solid-state imaging device 3, green color data is output in a wider band than other color data. Processing such as knee processing and gamma processing in a normal television camera or the like is also executed.

Thus, in this embodiment, after the process of converting the output signal of the CCD solid-state imaging device 3 into a video signal is executed on the image processing device 20 side, the image data resulting from this process is stored in the memory 26 by the CRT. It is output to the controller 27, and the CRT controller 27
8 is displayed.

According to the above configuration, since the output signal of the CCD solid-state imaging device 3 is data-compressed for each color signal, it is possible to effectively avoid image quality deterioration and to efficiently perform data compression. Therefore, as a whole, the data amount of a still image file to be transmitted can be reduced by a simple configuration in which a data compression circuit of this type is added to the configuration in which conversion processing into a video signal is performed on the editing device side. it can.
Thus, according to the first embodiment, many still images can be recorded on the IC memory card 10 having a small capacity.

Further, since the information of the image pickup system and the identification data of each color signal are added to the data of the compressed data and recorded, the CCD solid-state image pickup device can be used based on the information of the image pickup system and the identification data of each color signal. A video signal can be generated by a matrix operation corresponding to the arrangement of three pixels. Therefore, the image processing apparatus 20 can support an electronic still camera to which color filters having different arrangements are applied, based on the information of the imaging system and the identification data of each color signal.

In the above embodiment, the CCD
In the solid-state imaging device 3, a case has been described where yellow, cyan, magenta, and green color filters are sequentially arranged in the horizontal and vertical directions. However, the present invention is not limited to this, and various complementary color filters are sequentially arranged. Can be widely adapted to you.

Furthermore, in the above-described embodiment, a case has been described in which data is compressed by discrete cosine transform processing, quantization processing, and entropy coding processing. However, the present invention is not limited to this, and may be replaced with discrete cosine transform processing. Various data compression processes can be widely applied, for example, when applying the Haar transform process.

In the above-described embodiment, a case has been described in which the image processing apparatus 20 performs knee processing, gamma correction processing, and the like. However, the present invention is not limited to this. It may be performed on the side.

Further, in the above-described embodiment, the case where a still image file is recorded on an IC memory card has been described. However, the present invention is not limited to this, and when recording a still image file on various recording media such as a floppy disk, Can be widely applied to transmission via various transmission paths.

[0053]

As described above, according to the present invention, the color signal output from the image pickup device is compressed for each color signal and transmitted, so that the image quality is effectively prevented from deteriorating and the data is efficiently saved. Can be compressed. So overall,
In the configuration to execute the conversion process to the video signal on the editing device side,
With a simple configuration in which this type of data compression circuit is simply added, the data amount of a still image file to be transmitted can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electronic still camera according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an arrangement of pixels of a CCD solid-state imaging device.

FIG. 3 is a schematic diagram illustrating a configuration of a still image file.

FIG. 4 is a block diagram illustrating an image processing apparatus.

[Explanation of symbols]

1 ... Electronic still camera, 2 ... Optical system, 3 ... CCD
Solid-state imaging device, 4 ... analog-digital conversion circuit,
5, 26 ... memory, 6 ... data compression circuit, 10 ...
IC memory card, 11, 21, central processing unit,
20 image processing device, 22 data expansion circuit

Claims (4)

[Claims] A signal processing circuit for compressing a plurality of color signals output from an image sensor for each color signal;
An image pickup device for outputting an output signal of the signal processing circuit. 2. The image sensor, wherein a predetermined color filter is sequentially and cyclically assigned to each pixel, and the color signals are sequentially and cyclically switched and output in an order corresponding to an arrangement order of the color filters, and The signal processing circuit includes: a memory circuit that stores a color signal output from the image sensor and outputs the color signal for each color signal; and a data compression circuit that compresses an output signal of the memory circuit. The imaging device according to claim 1. 3. A recording medium for recording an output signal of an image sensor formed by a plurality of color signals, wherein the output signal is data-compressed for each of the color signals and recorded together with identification information of each of the color signals. Recording medium. 4. An image processing method comprising compressing data of a color signal output from an image sensor for each color signal, transmitting the data, and expanding the data to generate a video signal.