JPH05153544A - Still picture file system - Google Patents

Abstract

PURPOSE:To use information of video deterioration for reference information to decide a data recording compression ratio by confirming decoding still picture data before compressed data are recorded on a recording medium so as to recognize the video image deterioration in advance. CONSTITUTION:An analog video signal inputted to an input terminal AIN is converted into still picture data of a digital video signal by an A/D converter 11, written in a frame memory 14A via a switch SW1 sequentially in a prescribed timing for one frame. Then the data are read and converted into an analog video signal by a D/A converter 15 and outputted from an output terminal OUT. Thus, a still picture video image represented by the analog video signal inputted to the input terminal AIN is confirmed on a CRT display device.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a still image file system which compresses still image data and records it on a recording medium, reads the recorded data from the recording medium and restores it as still image data.

[0002]

BACKGROUND ART There is a still image file system in which still image data is compressed and recorded as a file on a disk, and the data read from the disk can be arbitrarily restored to the still image data. .. For example, as shown in FIG. 1, an analog video signal showing a still image is supplied from the input terminal AIN to the A / D converter 1 to be digitized, and is once written to the frame memory 2 as still image data via the switch SW. .. Also,
When still image data is received at the input terminal DIN, it is directly written to the frame memory 2 via the switch SW. The still image data written in the frame memory 2 is read from the frame memory 2 and compressed by the compressor 3. This compression is performed by, for example, JPEG (Joint Ph
otographic Experts Group) is the method specified in the. The still image compressed data output from the compressor 3 is supplied to the disk drive 4 and written on the disk. Writing and reading of the disk drive 4 are instructed by a microcomputer (not shown). Next, when reproducing an analog video signal indicating a still image from the data recorded on the disc, the switch SW is switched, and the output of the restorer 5 is relayed to the frame memory 2. When the disk drive 4 reads the still image compressed data written from the disk, the data is supplied to the decompressor 5. The decompressor 5 decompresses the still image compressed data into the still image data by the decompression action opposite to the action of the compressor 3. The restored still image data is written in the frame memory 2 via the switch SW, then read from the frame memory 2 and supplied to the D / A converter 6.
The reproduced analog video signal from the D / A converter 6 is output from the output terminal O.
Display device such as CRT display from UT (not shown)
It is designed to be output to.

However, in such a still picture file system, a still picture image is recorded on a recording medium such as a disk without confirming the deterioration of the still picture image due to the data compression operation of the compressor 3 at the time of data recording. In particular, as a compression method, a method such as the JPEG standard that cannot completely restore data may be adopted, and it is necessary to confirm deterioration of a still picture image due to compression at the time of recording.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a still picture file system capable of easily confirming a still picture image based on compressed still picture data before recording the compressed picture data on a recording medium.

[0005]

The still image file system of the present invention comprises a compression means for compressing still image data input at the time of data recording to generate compressed data, and compressed data on a recording medium at the time of data recording, and at the time of data reproduction. A still image file system comprising: a driving unit that reads out data recorded on a recording medium; and a decompressing unit that decompresses uncompressed data from compressed data read during data reproduction and outputs decompressed still image data. The compressed data output from the compression unit at the time of data recording is supplied to the decompression unit before recording on the recording medium, and the decompressed unit obtains and outputs the decompressed still image data.

[0006]

According to the still picture file system of the present invention, the compressed data output from the compression means at the time of data recording is supplied to the decompression means before recording on the recording medium to obtain decompressed still picture data. It is possible to check a still picture image based on still picture data that is compressed and restored before actually recording it on a recording medium.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 shows a still image file system according to the present invention. In this still image file system, analog input terminal AIN and digital input terminal D
IN and are provided. An A / D converter 11 is connected to the analog input terminal AIN, and switches SW1 and SW2 are connected to the output of the A / D converter 11. The digital input terminal DIN is directly connected to the switches SW1 and SW2. The switches SW1 and SW2 each have three fixed contacts A1, B1, C1, A2, B2 and C2, the fixed contacts A1 and A2 are connected to the A / D converter 11, and the fixed contacts B1 and B2 are digital input terminals. The signal input from DIN is supplied, and the fixed contact C1, C2 is supplied with the digital video signal restored by the restorer 13.

The frame memory 14A is connected to the selective output of the switch SW1, and the frame memory 14B is connected to the selective output of the switch SW2. Writing and reading of data in the frame memories 14A and 14B are controlled by a writing and reading circuit (not shown). A switch SW is provided for reading out the frame memories 14A and 14B.
3 and SW4 are connected. Switches SW3, SW4
Both have two fixed contacts A3, B3, A4, B4. The fixed contacts A3 and A4 are connected to the frame memory 14A, and the fixed contacts B3 and B4 are connected to the frame memory 14B. D / A for the selected output of switch SW3
The converter 15 is connected. The D / A converter 15 converts the digital video signal read from the frame memory 14A or 14B into an analog signal and supplies the analog signal to the output terminal OUT. The compressor 16 is connected to the selected output of the switch SW4. The data compressed by the compressor 16 is supplied to the disk drive 12. Disk drive 12
Writes a signal from the compressor 16 to a rewritable disk such as a magneto-optical disk at the time of recording data, and reads recorded data from the disk at the time of reproducing data. The switch SW5 is connected to the read output of the disk drive 12. The switch SW5 includes two fixed contacts A5 and B5. The fixed contact A5 is supplied with read data from the disk drive 12, and the fixed contact B5 is supplied with compressed data from the compressor 16. The selected output of the switch SW5 is connected to the restorer 13.

The switching control of the switches SW1 to SW5 is controlled by the control circuit 17. The control circuit 17 includes, for example, a microcomputer, and a keyboard 18
It operates as described later according to the key operation of. The keyboard 18 is provided with keys such as a recording key, a confirmation key, an execution key, and a reproduction key (both not shown) which will be described later. In addition,
In FIG. 2, the part surrounded by the broken line is integrally formed.

The compressor 16 is based on the JPEG standard, and as shown in FIG. 3, a DCT (Discrete Cosine Transf).
orm) converter 21, a quantization circuit 22, an entropy encoder 23, and memories 24 and 25. DC
The T converter 21 divides the still image data into blocks of 8 × 8 pixels, and performs two-dimensional DCT conversion for each block. This D
8 × 8 (64) pixel data is 8 × by CT conversion
Converted to a DCT coefficient of 8. One coefficient in the upper left block of the image shows a DC component, and the remaining blocks show an AC component. The quantization circuit 22 linearly quantizes 64 DCT coefficients using a quantization table with different step sizes for each coefficient position. The quantization table is written in the memory 24 in advance. The quantized DCT coefficient is supplied to the entropy encoder 23, where it is Huffman-encoded according to a code table stored in advance in the memory 25. This becomes the still image compressed data.

As shown in FIG. 4, the decompressor 13 includes an entropy decoder 31, an inverse quantization circuit 32, and an IDCT (Inve).
rse Discrete Cosine Transform) converter 33 and memories 34 and 35. Entropy decoder 3
Reference numeral 1 Huffman-decodes the still image compressed data according to a decoding table stored in the memory 34 in advance. The decoded data are quantized DCT coefficients, which are dequantized by the dequantization circuit 32. Inverse quantization is memory 3
5 is performed by using an inverse quantization table written in advance. The dequantized data is supplied to the IDCT converter 33 and converted into still image non-compressed data.

Regarding the decompressor 13 and the compressor 16, "Outline of International Standard System for Color Still Image Coding (Part 1)" (Omachi, Ono, Journal of the Institute of Image Electronics Engineers, Vol. 20, No. 1)
No., 1991, pp. 50-58), JP-A-63-
It is specifically described in publications such as 103583. Next, the file format of still image data will be described. The file structure includes a volume part, a compression parameter part, a disk correspondence table part, a directory part and a data part. One volume section is provided at a fixed sector address of the disc, and is a portion in which management information regarding the entire disc is recorded. The volume part has an area called a management flag consisting of 4 bytes, one of which is
It indicates whether or not even one still image data compressed by bytes (8 bits) is included. Also,
The volume section is provided with a data information section for recording the directory start sector address, the directory area size, the number of registered directories, the data start sector address, the data section free start sector address, and the data free size.

The compression parameter section has a size of one sector, is provided at a predetermined sector address for each disk, and records default compression parameters necessary for reproducing compressed data. The compression parameter consists of the inverse quantization table and the Huffman decoding table described above.
The disc correspondence table section is provided with a disc on which reproduction control information is present, and specifies an image recording disc and an audio recording disc used for the reproduction control. The directory part is a table showing the start sector address of each file in the data part.

The data section is composed of a data header and a data body section for each file. A body header is provided in the data body depending on the type of data. In the data header, information such as the head sector address of the next file, the type of data, the area according to the type of data that records the image size, the body header size when the body header exists, the size of the body part, etc. are recorded. To be done. The data types include compressed data, non-compressed data, reduced data, and the like.

This file format is NHK.
High-definition still image disc system Technical standards are followed. Next, the operation of the still image file system according to the present invention at the time of recording and reproducing will be described. A CRT display (not shown) is connected to the output terminal OUT.

When the control circuit 17 detects the operation of the recording key of the keyboard 18, as shown in FIG. 5, first, the switch SW1 is the fixed contact A1 or B1, the switch SW2 is the fixed contact C2, the switch SW3 is the fixed contact A3, Switch SW4 is fixed contact A4, switch SW5 is fixed contact B5
To each selected position (step S1). For example, the analog video signal supplied to the input terminal AIN is sampled by the A / D converter 11 and converted into still picture data as a digital video signal, and then the switch S
It is supplied to the frame memory 14A via W1. The supplied still image data is sequentially written to the frame memory 14A at a predetermined write timing, and one frame of still image data forming a still image video is stored in the frame memory 14A.
Held in. The held still image data is repeatedly read from the frame memory 14A at a predetermined read timing and supplied to the D / A converter 15 via the switch SW3. The D / A converter 15 converts the supplied still image data into an analog video signal and outputs it from the output terminal OUT. As a result, it is possible to confirm the still image video indicated by the analog video signal supplied to the input terminal AIN on the CRT display.

The still image data read from the frame memory 14A is converted into compressed data by the compressor 16. Compressed data is sent from the compressor 16 to switch SW5.
Is supplied to the restoring device 13 via. The decompressor 13 converts the compressed data into uncompressed data, and the uncompressed data, that is, decompressed still image data, is supplied to the frame memory 14B via the switch SW2. The restored still image data supplied to the frame memory 14B is sequentially written at a predetermined write timing, and the restored still image data for one frame forming a still image video is held in the frame memory 14B. The restored restored still image data is stored in the frame memory 14
It is repeatedly read from B at a predetermined read timing.

When the image confirmation key is operated after the operation of the record key of the keyboard 18 (step S2), the control circuit 17 changes the selected position of the switch SW3 from the fixed contacts A3 to B3 each time the image confirmation key is operated. Alternatively, the fixed contact B3 is switched to A3 (steps S3 to S7). Therefore, when the switch SW3 is switched from the fixed contact A3 to the selected position of B3, the restored still image data read from the frame memory 14B is transferred via the switch SW3 to the D / A converter 1.
5 is supplied. The D / A converter 15 converts the supplied restored still image data into an analog video signal and outputs it at the output terminal OU.
Output from T. After converting to compressed data by this,
It is possible to confirm a still picture image by a video signal which has been restored to uncompressed data on the CRT display.
Further, when the switch SW3 is switched from the fixed contact B3 to the selected position of A3, the still image data read from the frame memory 14A is supplied to the D / A converter 15 via the switch SW3, and the original still image image is displayed. Is displayed on the CRT display. Therefore, the original still image image and the restored still image image after compression can be compared by operating the image confirmation key.

During the image checking operation, the keyboard 18
When the execution key is operated (step S8), the control circuit 17 starts the data recording operation (step S9). That is, the control circuit 17 instructs the disk drive 12 to write. Therefore, the disk drive 12 writes the compressed data output from the compressor 16 as a file on the disk.

On the other hand, when the reproduction key of the keyboard 18 is operated, the control circuit 17 causes the switch S to switch as shown in FIG.
Switch W5 to the selected position of fixed contact A5 (step S
11). Further, which of the frame memories 14A and 14B the restored still image data is stored is selected and set by a predetermined key operation of the keyboard 18 (step S1).
2) When the frame memory 14A is selected, the control circuit 17 controls the switch SW1 to the selected position of the fixed contact C1 and the switch SW3 to the selected position of the fixed contact A3 (step S13). When the frame memory 14A is selected, the switch SW2 is controlled to the selected position of the fixed contact C2, and the switch SW3 is controlled to the selected position of the fixed contact B3 (step S14). Then, the data reproducing operation is started (step S15). That is, the control circuit 17 reads out a file designated from the keyboard 18 by starting the data reproducing operation, for example.
Command to. Therefore, the compressed data is read from the disk drive 12. The compressed data is the switch S
It is supplied to the decompressor 13 via W5, and is converted into still image non-compressed data there. When the frame memory 14A is selected, uncompressed data, that is, decompressed still image data is supplied to the frame memory 14A via the switch SW1, and the decompressed still image data supplied to the frame memory 14A is sequentially written in a predetermined manner. The restored still image data for one frame, which is written at a timing and forms a still image, is held in the frame memory 14A. The held restored still image data is read from the frame memory 14A at a predetermined read timing and supplied to the D / A converter 15 via the switch SW3. The D / A converter 15 converts the supplied restored still image data into an analog video signal and outputs it from the output terminal OUT. This allows the playback still image to be CR
It can be confirmed on the T display. The same applies when the frame memory 14B is selected.

Although the first and second frame memories 14A and 14B are provided in the above embodiment, a restored still image stored in the second frame memory 14B at the time of recording is further provided with a third frame memory. The data is recompressed by the compressor 16, restored by the decompressor 13, and stored in the third frame memory, and the still image video based on the still image data stored in the first to third frame memories is displayed on the CRT. By comparing with, it is possible to confirm the degree of deterioration of the image due to repeated compression.

[0022]

According to the still picture file system of the present invention, the compressed data output from the compression means at the time of data recording is supplied to the decompression means before recording on the recording medium to obtain the decompressed still picture data from the decompression means. It is possible to confirm before actually recording a still image image based on still image data obtained by data compression and decompression. Therefore, it is possible to know in advance how much the image is deteriorated due to the data compression recording, which can be used as a reference when determining the compression ratio of the data recording.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a conventional still image file system.

FIG. 2 is a block diagram showing an embodiment of the present invention.

3 is a block diagram showing a configuration of a compressor in the system of FIG.

FIG. 4 is a block diagram showing a configuration of a restorer in the system of FIG.

FIG. 5 is a flowchart showing an operation of the control circuit during recording.

FIG. 6 is a flowchart showing the operation of the control circuit during reproduction.

[Explanation of symbols for main parts]

 2,14A, 14B Frame memory 3,16 Compressor 4,12 Disk drive 5,13 Decompressor

Claims (2)

[Claims] 1. A compression means for compressing still image data input at the time of data recording to generate compressed data, and a compression means for recording the compressed data on a recording medium at the time of recording the data and reading the data recorded on the recording medium at the time of reproducing the data. A still image file system comprising: a driving unit; and a decompressing unit that decompresses uncompressed data from compressed data read at the time of data reproduction and outputs as decompressed still image data. The compressed image data is supplied to the decompression means before being recorded on a recording medium, and decompressed still image data is obtained from the decompression means and output. 2. At least two frame memories are provided, and one frame of still image data input to one frame memory at the time of data recording is stored, and one frame output from the restoring means is stored in the other frame memory. 2. The still image file system according to claim 1, wherein the restored still image data is stored, and data of either one of both frame memories is selectively read and output according to an operation command.