JP3066531B2 - Digital image processing system, imaging recording device and reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image processing system for compressing a recorded image and recording and reproducing the same, and an imaging recording device and a reproducing device used in the system.

[Prior Art] An electronic still video camera using a magnetic floppy disk as an image recording medium is known. However, with the recent high integration and low price of semiconductor memories, a semiconductor memory device has been used in an image recording medium. The still video camera used is promising.

[Problem to be Solved by the Invention] The number of pixels of an image sensor of a still video camera, for example, a CCD image sensor is still about 500,000 pixels at present, and it is likely that a pixel exceeding 1 million pixels will be realized in the near future. It is.
If data of a large number of pixels is to be stored in a memory without deterioration, 4 megabits are required for a 500,000 pixel image, assuming that 8 bits per pixel. If you try to store 25 frames worth of images on the same level as a magnetic floppy, 25 times that is 100
Although megabits are required and the integration of semiconductor memories is progressing, it is disadvantageous in terms of cost, size and power consumption.

Therefore, an object of the present invention is to provide a digital image processing system that solves such a problem, and an imaging recording device and a reproducing device used in the system.

[Means for Solving the Problems] A digital image processing system according to the present invention comprises: an imaging unit; an A / D conversion unit that A / D converts an output of the imaging unit; and a digital image output of the A / D conversion unit. A first data compression means for compressing data by a first data compression method using non-linear quantization, and a digital image output of the A / D conversion means by a second data compression method using orthogonal transformation quantization. A second data compression unit for compressing data, one of the first and second data compression units is selected, and corresponding to the selected data compression unit, Switching means for outputting a selection signal for selecting one of a plurality of data decompression means having different data decompression methods, and a data pressure selected by the switching means An imaging and recording apparatus having recording means for recording a digital image signal data compressed by a compression means; and a data expansion device which reproduces the digital image signal recorded by the imaging and recording apparatus in accordance with the selection signal. And a reproducing apparatus having an image signal reproducing means for selecting a corresponding data expanding means from a plurality of data expanding means having a system and expanding data of the recorded digital image signal.

An image-capturing recording apparatus according to the present invention includes an image-capturing unit, an A / D converter that A / D-converts an output of the image-capturing unit, and a first imager that uses a non-linear quantization of a digital image output of the A / D converter.
A first data compression means for compressing data by the data compression method of the first aspect, and a second data compression means for compressing the digital image output of the A / D conversion means by the second data compression method using orthogonal transform quantization. Data compression means, and the first
And one of the second data compression means is selected, and among the plurality of data decompression means having different data decompression methods in the reproducing apparatus corresponding to the selected data compression means. Switching means for outputting a selection signal for selecting one data expansion means, and recording means for recording a digital image signal compressed by the data compression means selected by the switching means. .

A playback device according to the present invention includes a first data compression unit for performing data compression on a digital image output after A / D conversion of an output of an imaging unit using a first data compression method using nonlinear quantization; A second data compression means for compressing the digital image output of the A / D conversion means by a second data compression method using orthogonal transform quantization; and And selecting one of a plurality of data decompression means having different data decompression methods in the reproducing apparatus in accordance with the selected data compression means. Switching means for outputting a selection signal of
Recording means for recording a digital image signal compressed by the data compression means selected by the switching means; and a reproducing apparatus for reproducing a digital image signal recorded by an image recording apparatus, An image signal reproducing means for selecting a corresponding data decompression means from a plurality of data decompression means of different data decompression systems and decompressing the recorded digital image signal.

[Operation] By the above means, an appropriate compression process can be selected according to the image data, and the amount of data required for recording can be reduced. Therefore, the image recording medium can be used effectively.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention in which two compression processes can be selected. Reference numeral 10 denotes a camera body, and 12 denotes a solid-state memory device that records (stores) a captured image. Light from a subject to be photographed is transmitted through an imaging lens 14 to an image sensor 16.
And is photoelectrically converted by the image sensor 16. The output of the image sensor 16 is digitized by the A / D converter 18. The compression selection circuit 20 is a circuit for selecting which compression processing of the compression circuits 22 and 24 is to be performed on the output data of the A / D converter 18, and switches the switch 26 according to the selection result. D
The output data of the converter 18 is supplied to either the compression circuit 22 or 24. The data compressed by the compression circuits 22 and 24 is transferred to the solid-state memory device 12 and stored in a predetermined format.

When the camera body 10 has only a recording function, the solid-state memory device 12 is detached from the camera body 10 and connected to a reproducing device (not shown) to reproduce the recorded image. , The playback function is also shown. That is, when reproducing the image stored in the solid-state memory device 12, data stored in the solid-state memory device 12 is read out, and the expansion circuit 2 that performs expansion processing corresponding to compression processing at the time of recording is performed by the switch 27.
Supplied to 8,30. That is, the expansion circuit 28 expands the compressed data by the compression circuit 22, and the expansion circuit 30 expands the compressed data by the compression circuit 24.

The image data restored by the expansion circuits 28 and 30 is returned to an analog signal by the D / A converter 32, and is converted to a video signal by the video circuit 34.

Since FIG. 1 mainly illustrates the flow of image signals, switches and display devices for various operation instructions,
Further, a control circuit for controlling the whole, a power supply circuit and the like are omitted.

Next, the compression processing in the compression circuits 22 and 24 will be specifically described. The natural image has a very strong correlation with the adjacent pixels, and when the difference between the adjacent pixels is calculated, in most cases, the value becomes a small value. In other words, if the difference is stored as compared with storing (recording) the absolute value (for example, 8 bits) of the image, the data amount can be significantly reduced. This compression method is called DPCM. Also, as other compression methods, ADPCM which improved this DPCM and adaptively changes the nonlinearity of the nonlinear quantization circuit according to the image,
There is a method of transforming an image into the frequency domain and compressing the image by increasing the weight of the coefficient of the low frequency component and decreasing the weight of the coefficient of the high frequency component (for example, a discrete cosine transform).

FIG. 2 is a block diagram showing a configuration of a compression circuit based on DPCM, and FIG. 3 is a block diagram showing a configuration of a decompression circuit for decompressing the compressed data shown in FIG. For more information, see Nikkan Kogyo Shimbun's 14
It is described on pages 6-159. In FIG. 3, 40 is a subtractor, 42
Is a non-linear quantization circuit, 44 is a representative value setting circuit, 46 is an adder, 48 is a delay circuit, and 50 is a coefficient multiplier. Subtractor 40
Subtracts the output of the coefficient multiplier 50 from the input 8-bit image data. The non-linear quantization circuit 42 non-linearly quantizes the output of the subtracter 40, whereby the input image data is compressed from 8 bits to, for example, 3 bits. Non-linear quantization circuit
42 3-bit output is the target compressed data.

The representative value setting circuit 44 returns the 3-bit output of the nonlinear quantization circuit 42 to an 8-bit representative value. The adding circuit 46 adds the coefficient value multiplication circuit 50 to the representative value data (8 bits) of the output of the representative value setting circuit 44. Add the outputs of The output of the adder 46 is delayed by one pixel by a delay circuit 48, specifically, a data latch circuit, and applied to a coefficient multiplication circuit 50. Coefficient multiplication circuit 50
Multiplies by a constant coefficient, for example, 0.95, and applies the multiplication result to the subtraction circuit 40 and the adder 46 when the next data is input.

By repeating the above, 8-bit data is compressed to 3 bits.

The nonlinear quantization circuit 42, the representative value calculation circuit 44, and the coefficient multiplication circuit 50 can be realized in the form of a ROM table conversion, and can perform high-speed processing.

Next, the expansion circuit shown in FIG. 3 will be described. 52 is a representative value setting circuit, 54 is an adder, 56 is a delay circuit for one pixel, and 58 is a coefficient multiplication circuit. The representative value setting circuit 52 is a circuit similar to the representative value setting circuit 44 in FIG. 3, and converts input data (3 bits) into an 8-bit representative value. The adder 54 adds the output of the coefficient multiplying circuit 58 to the output of the representative value setting circuit 52. Adder
The output of 54 becomes the target restored data. The delay circuit 56 is a data latch similarly to the delay circuit 48, and delays the output of the adder 54 by one pixel and supplies it to the coefficient multiplying circuit 58. The coefficient multiplying circuit 58 multiplies a constant coefficient, for example, 0.95, and
Output to 54. By the above loop processing, the input compressed data (3 bits) is expanded to 8 bits and restored.

The discrete cosine transform method is described in detail in Nikkan Kogyo Shimbun, 179-1
Since it is explained on page 95, its outline is briefly explained. First, image data is orthogonally transformed by discrete cosine transform to extract frequency components. The frequency component is multiplied by a coefficient that leaves a low frequency component and cuts a high frequency component. Thereby, image information can be compressed. When the frequency component of the image is closer to the lower side, it is possible to perform good compression with little deterioration.

Next, selection criteria by the compression selection circuit 20 will be described. Simply, the compression circuits 22 and 24 themselves or similar circuits perform compression processing by each of a plurality of compression methods, and select the one with a smaller amount of data after compression. At this time, the data amount can be compared by a well-known method, for example, by using a digital comparator. If it is desired to speed up the selection, for example, a plurality of compression processes may be performed only on the central portion of the image, and the compression process may be selected based on the data amount. In addition, the compression processing of one compression circuit 22 is a method in which the data amount after compression is always constant, and the compression processing of the other compression circuit 24 changes the data amount after compression in accordance with the target image. Alternatively, it may be determined which of the compression circuit 22 and the compression circuit 24 is to be selected only from the output data amount of the compression circuit 24.

The same applies to image data not only in black and white but also in color. Further, the selection of the compression method may be made manually instead of automatically.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, since the data amount of an image to be recorded can be compressed by a method suitable for each image, the image recording medium can be more effectively used. Will be able to take advantage of it.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a compression circuit, and FIG. 3 is a block diagram showing a configuration of a decompression circuit. 10: Camera body, 12: Solid-state memory device, 14: Shooting lens, 1
6: Image sensor, 18: A / D converter, 20: Compression selection circuit, 22, 24:
Compression circuit, 26: switch, 28, 30: expansion circuit, 32: D / A converter, 34: video circuit

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tadashi Takaiwa 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Tamagawa Works of Canon Inc. (56) References JP-A-63-286078 (JP, A) JP-A-64- 879 (JP, A) JP-A-62-166680 (JP, A) JP-A-2-104078 (JP, A) JP-A-2-203684 (JP, A) JP-A-62-269581 (JP, A) JP-A-63-135077 (JP, A) JP-A-1-292987 (JP, A) JP-A-63-274275 (JP, A) JP-A-59-70091 (JP, A)

Claims (3)

(57) [Claims] 1. An image pickup means, an A / D conversion means for performing A / D conversion of an output of the image pickup means, and a digital image output of the A / D conversion means which is converted into data by a first data compression method using non-linear quantization. A first data compression unit for compressing, a second data compression unit for compressing the digital image output of the A / D conversion unit by a second data compression method using orthogonal transform quantization, One of the first and second data compression means is selected, and a plurality of data decompression means having different data decompression methods in the reproducing apparatus corresponding to the selected data compression means are selected. Switching means for outputting a selection signal for selecting one of the data decompression means, and recording the digital image signal compressed by the data compression means selected by the switching means. Means for reproducing a digital image signal recorded by the image capturing and recording apparatus, corresponding data from a plurality of data decompressing means having different data decompression methods according to the selection signal. A reproducing apparatus having an image signal reproducing means for selecting an expanding means and expanding the recorded digital image signal by data. 2. An image pickup means, an A / D conversion means for A / D converting an output of the image pickup means, and a first data compression system using nonlinear quantization of a digital image output of the A / D conversion means. A first data compression means for compressing data by a second data compression means for compressing the digital image output of the A / D conversion means by a second data compression method using orthogonal transform quantization And selecting one of the first and second data compression means and a plurality of data having different data decompression schemes in the playback device corresponding to the selected data compression means. Switching means for outputting a selection signal for selecting one of the data expanding means from the expanding means; and recording a digital image signal compressed by the data compressing means selected by the switching means. Imaging and recording apparatus characterized by having a that recording means. 3. A first data compression means for compressing a digital image output obtained by A / D-converting an output of an imaging means by a first data compression method using non-linear quantization,
A second data compression means for compressing the digital image output of the A / D conversion means by a second data compression method using orthogonal transform quantization; and And selecting one of a plurality of data decompression means having different data decompression methods in the reproducing apparatus in accordance with the selected data compression means. A reproducing device for reproducing a digital image signal recorded by an imaging and recording device, comprising: switching means for outputting a selection signal of the above; and recording means for recording a digital image signal compressed by the data compression means selected by the switching means. Wherein a corresponding data decompression means is selected from a plurality of data decompression means of different data decompression methods according to the selection signal. To the playback apparatus characterized by having an image signal reproducing means for data decompressing a digital image signal the recorded.