JP2531616B2 - Image signal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to an image signal recording apparatus, and more particularly to an apparatus for processing an image signal in a pixel unit including a predetermined number of pixels and recording compressed image information in a recording medium. It is about.

<Summary of Disclosure> The present specification and drawings process an image signal in a pixel block unit including a predetermined number of pixels, and record image information compressed at a different compression rate for each pixel block on a recording track on a recording medium. In the device for recording, only main image information of the image information of each pixel block is recorded in a first area arranged at a predetermined position in the recording track, and a first area other than the first area is recorded in the recording track. A technique for providing an image signal recording device for recording image information other than the main image information in the image information of each pixel block in the area 2 is disclosed.

<Prior Art> An example of this type of information compression, which has already been announced, is a time-axis conversion band compression method (TAT; Time A is Tr).
(It is called ansform) as an example.

FIG. 2 is a diagram for explaining conventional information compression. The original signal determines whether the information is rough or dense for each group divided into a predetermined number of samples as shown by a dotted line. Then, in the group judged to be dense, all the data obtained by sampling the original signal are transmitted as transmission data, and in the group judged to be coarse, only a part of all the data is treated as transmission data. , And others are not transmitted as thinned-out data.

As a result, the number of data transmitted per unit time is reduced, and the bandwidth of the transmission signal can be compressed. Information compression is performed in this way. Further, the data after transmission is supplied to a decoding system, and the decoding system approximately restores the thinned-out data using the transmission data to obtain interpolation data. Since this interpolated data corresponds to the coarse information, it becomes data that is very close to the thinned-out data, and the actual amount of information does not change compared to the case where all the data is transmitted. Will be significantly compressed.

At this time, transmit all data in the group,
Whether or not to transmit a part of the data is determined by examining the details of the original signal. This determination information is also transmitted as transmission mode information at the same time.

<Problems to be Solved by the Invention> By the way, as an effective method of utilizing the above-described information compression, it is conceivable to record and reproduce the information compressed by magnetic recording or the like. However, in the recording / reproducing system, if there is an error in the above-mentioned mode judgment signal or if it is erased due to dropout, etc., the information amount of each group is unknown and the recording position of the information of each sample is unknown. Cannot be specified and the original information cannot be restored. Further, the information after that cannot be restored unless some measure is taken next to synchronize the mode determination signal and the compressed information signal. Further, even if such a synchronizing means is taken, all the restoration / restoring information becomes invalid until the synchronization is taken. Therefore, if an error frequently occurs in the mode determination signal, the information is recorded. That was what it meant.

The present invention has been made in view of the problems represented by the above, and SN
Even for a recording / reproducing system with a poor ratio, when processing image signals in pixel units consisting of a prescribed number of pixels and recording image information compressed at a different compression rate for each pixel block on a recording medium, the maximum It is an object of the present invention to provide an image signal recording device capable of recording so that excellent restoration information can be obtained.

<Means for Solving the Problems> With the above-mentioned object, in the present invention, in the first area arranged at a predetermined position in the recording track, the main part of the image information of each pixel block is Only record image information,
In the recording track, image information other than the main image information in the image information of each pixel block is recorded in the second area other than the first area.

<Operation> With the configuration as described above, at least the main image information can be restored, and deterioration of the restored information can be minimized even in a recording / reproducing system having a poor SN ratio.

<Embodiment> An embodiment in which the present invention is applied to a television signal recording / reproducing apparatus will be described in detail below.

FIG. 1 is a diagram showing a schematic configuration of a recording system in the apparatus of this embodiment. The input television signal is converted by the signal conversion circuit 1 into a signal form suitable for band compression, and further array-converted by the array conversion circuit 2 into a data array suitable for band compression. The array-converted pixel data is supplied to the band compression circuit 3.

FIG. 3 is a diagram for explaining band compression in a pixel block obtained by dividing one screen into a large number. In the figure, ⊚ indicates basic pixel data which is the main image information in the present embodiment in the transmission data, ◯ is additional pixel data which is image information other than the main image information in the present embodiment in the transmission data,
X indicates thinning data. In the figure, E represents the data transmission mode and the thinning data of the pixel block in the data transmission mode in which the band compression is not performed, and C is the data transmission mode in which the band compression is performed. Hereinafter, these are simply referred to as E mode and C mode. As is clear from the figure, C mode C is transmitted at a compression rate of 1/4 that of E mode. In this way, when thinning out the vertical and horizontal directions of the screen in each pixel block, it is necessary to correlate each pixel block and its adjacent pixel blocks.

According to this, the signal conversion circuit 1 and the array conversion circuit 2 in FIG. 1 perform the following processing, for example. That is, the input television signal is 1/1/2 of the first half of the horizontal scanning period.
The line-sequential color difference signals ( _CN and _CW ) are arranged in the 5th part, and the signal is converted so that the luminance signal can be distributed in the 4 / 5th part of the latter half.
FIG. 4B is a diagram schematically representing this signal as a reproduction screen. Further, in the array conversion circuit 2, the data is read out using a frame memory or the like so that C _N and C _W are arranged at positions having correlation in the vertical direction. The signal thus obtained is schematically represented in FIG. 4 (A).

FIG. 5 is a diagram showing a specific example of the signal conversion circuit 1 in FIG. The NTSC signal as a television signal is first supplied to the Y-C separation circuit 21 and separated into a luminance signal (Y) and a chroma signal (C). The chroma signal is further converted into two types of color difference signals (C _N , C _W ) by a known demodulation circuit 22. C _N and C _W are analog-to-digital converters (A / D) 2 respectively
It is supplied to the vertical filters 25, 26 via 3, 24. The filters 25 and 26 limit the band in the vertical direction of the screen for line-sequencing, and by switching the switch 27 every horizontal scanning period, the outputs of these filters 25 and 26 are line-sequential. Line-sequential color difference signal is 1/5 time base compressor 30
Is 1/5 time-axis compressed, while the luminance signal is passed through A / D28
The 4/5 time axis compressor 29 compresses the time axis to 4/5. The time-axis-compressed luminance signal and line-sequential color-difference signal are selectively output by the switch 31 to obtain a video signal of the form shown in FIG. 4 (B).

Therefore, in the array conversion circuit 2, C _N of the 2i−1th line
The position in the frame memory as to place the C _W of 2i-th line (j + i) lines to the i th line is converted. Here, i is an integer of 1 to j.

The video signal thus obtained is then subjected to band compression processing as described below. The data output from the array conversion circuit 2 is the memory 4, the C mode data generation circuit 5, the mode determination circuit 6
Is supplied to.

In the C mode data generation circuit 5, at the same time when the data is input, the thinning corresponding to FIG. 3 is performed, and the transmission data for one field in the C mode, that is, the main image information indicated by ⊚ in FIG. Certain basic pixel data is stored in the memory 36. At the same time, all the pixel data for one field is stored in the frame memory in the memory 4.

On the other hand, the interpolation data corresponding to the thinning data is also calculated by the interpolation circuit 35 based on the data of the C mode, and is output to the mode determination circuit 6. The mode determination circuit 6 calculates the difference between the actual pixel data and the interpolated data, calculates the difference between these pixel blocks (distortion value), and outputs a mode determination signal based on this. One field is stored in the memory 37.

 The discriminating operation of the mode discriminating circuit 6 will be described.

The mode discrimination circuit 6 obtains the distribution of the distortion values of all pixel blocks until the data of the next field is input, determines the mode of each block based on this distribution, and determines the result as the above mode. It is output as a discrimination signal and stored in the memory 37. That is, in order to equalize the transmission time of the video signal for one field, it is necessary to keep the ratio of the number of pixel blocks transmitted in the C mode and the number of pixel blocks transmitted in the E mode constant. For example, C mode 2 /
If the E mode is set to 1/3, the overall bandwidth compression ratio is (2 /
3 x 1/4 + 1 x 1/3 =) 1/2. Therefore, based on the distribution of the distortion values of the pixel blocks, a distortion threshold value for determining how much the distortion value is to be used for the distribution of the C mode and the E mode is obtained.

Then, the distortion value stored at the timing when the video signal of the next field is output is sequentially read out and compared with the distortion threshold value to determine the transmission mode. The transmission mode is determined so that when the distortion value read here and the distortion threshold value match, the transmission in the C mode and the E mode is performed at a predetermined ratio.

The switch 7 is a switch connected to the C side in the first half of each field and to the E side in the second half. That is, all Cs on one screen
The transmission data (basic pixel data) in the mode is read by the memory 36 and output from the switch 7 in the first half of each field period. At this time, the overall band compression ratio is 1/2,
Since the band reduction rate of C mode is 1/4, considering that each data is transmitted at the same interval, all C mode data of the entire screen will be read in the period of 1/2 of one field. .

Next, the remaining data of the pixel block designated to the E mode, that is, the additional pixel data which is image information other than the main image information shown by ◯ in FIG. It is read in the latter half of the field. At this time, if only the remaining data is transmitted, the bandwidth ratio is 3/4 and the frequency of the E-mode pixel block is 1/3, so that this is also all read in the period of 1/2 of one field. This reading method is performed by using the mode determination data for one field stored in the memory 37, reading the data, driving the address control circuit 38, and designating the read address of the memory 37.

The output data of the switch 7 is converted into an analog signal again by a digital-analog converter (D / A) 8, band-limited by a low pulse filter (LPF) 9, and supplied to a post FM modulation circuit 10. On the other hand, the above-mentioned mode determination signal is digitally modulated by the digital modulation circuit 12, for example, the well-known MFMBPM, and supplied to the multiplier 13. In the multiplier 13, the digitally modulated mode decision signal modulates the output carrier of the carrier generation circuit 14. If the number of pixels is 900 × 240 per screen and the number of pixels on the pixel block is 4 × 4, the number of pixel blocks in one screen is 225 × 60, and the frequency of the mode discrimination signal is (225 × 60 × 60 =) It becomes 910KHz. According to this, the carrier frequency of the FM modulation circuit 10 is set to about 2 to 3 MHz, and the cutoff frequency of the high pass filter (HPF) 11 is 1.5 MHz.
In a degree, the modulated mode determination signal output from the multiplier 13 and the FM modulated video signal output from the HPF 11 can be frequency-multiplexed by the adder 15.

The output signal of the adder 15 is supplied to the rotary magnetic head 17 via the amplifier 16 and recorded on the magnetic tape 18. FIG. 6 is a diagram showing a recording format on the magnetic tape, and as shown in the figure, it is recorded on the helical track 19 as in the conventional home video tape recorder. In the figure, 19A is C mode data, that is, the recording area of basic pixels, and 19B.
Indicates a recording area of the remaining data (additional pixels) of the pixel block designated in the E mode.

FIG. 7 is a diagram showing a schematic configuration of a reproducing system in the apparatus of this embodiment. The reproduction signal of the head 17 is amplified by the reproduction amplifier 41 and supplied to the HPF 42 and LPF 47. FM on the HPF42
The modulated video signal is separated, the FM demodulation circuit 43 recovers the FM, and the A / D 44 returns the digital signal. The output of the A / D 44 is supplied to the C mode interpolation circuit 45, and the approximate interpolation data of the non-transmission data corresponding to X in FIG. 3C is calculated using the transmission data of the C mode in the entire screen.

On the other hand, the modulated mode determination signal is separated by the LPF 47, supplied to the address and timing control circuit via the analog demodulation circuit 48 and the digital demodulation circuit 49, and controls the switch 46. From the memory in the C-mode interpolation circuit 45, all the C-mode data and the interpolation data corresponding to the video signal for one field are sequentially read out, and all the pixel data can be obtained only by this data, and the restored video signal can be obtained. You can

On the other hand, the remaining pixels designated in the E mode are stored in the memory 52 together with the basic pixel data designated in the E mode. The address at this time is controlled by the control circuit 53. Then, all the pixel data output from the C mode interpolation circuit 45 and the E mode data stored in the memory 52 are replaced as much as possible. When it is determined that there are many errors in the reproduction mode determination signal, the switch 46 is always connected to the C side.

As a result, the pixel data for one screen is transferred to the array conversion circuit.
The data is stored in the memory in 50 in accordance with FIG. 4 (A). In the array conversion circuit 50, the memory is controlled so that the data input in the order conforming to FIG. 4 (A) is output in the order conforming to FIG. 4 (B). Further, the data output from the array conversion circuit 50 is supplied to the signal conversion circuit 51, converted into an NTSC signal and output.

FIG. 8 is a diagram showing a specific example of the signal conversion circuit 51 in FIG. Among the output data of the array conversion circuit 50, the luminance signal data is supplied to the 5/4 times time axis expansion circuit 62 and the line-sequential color difference signal data is supplied to the 5 times time axis expansion circuit 63 via the switch 61. These time axis expansion circuits 62 and 63 output the same horizontal scanning line at the same timing.

The data corresponding to C _N and C _W in the line-sequential color difference signal data output from the quintuple time axis expansion circuit 63 is distributed by the switch 64 and supplied to the vertical direction interpolation circuits 65 and 66, respectively.
The vertical direction interpolation circuits 65 and 66 generate data for lines in which C _N and C _W do not exist, respectively.

The D / A67, D / A68 and D / 69 respectively output the data of C _N , C _W and Y as analog signals. The C _N and C _W thus restored are supplied to the modulation circuit 70, converted into the original chroma signal in the circuit 70, mixed with the luminance signal restored in the mixing circuit 71, and mixed in the NTSC.
Signaled.

In the apparatus of the above-mentioned embodiment, even when the mode judgment signal cannot be reproduced or when a large number of errors occur, only the C mode data, that is, the basic pixel data can be restored. Since the interpolation can be performed by using it, the reproduction / restoration image quality is not extremely deteriorated.

In the above embodiment, the case where the number of modes is two has been described, but it is also possible to set three or more.

Further, the mode determination signal is frequency-multiplexed with the compressed video signal and recorded, but it is also possible to take another recording mode such as recording in a region different from the video signal.

<Explanation of Effects> As described above, according to the present invention, even for a recording / reproducing system having a poor SN ratio, an image signal is processed in a pixel unit including a predetermined number of pixels, and different compression is performed for each pixel block. An image signal recording device is obtained when recording image information compressed at a rate on a recording medium.

[Brief description of drawings]

FIG. 1 is a diagram showing a recording system of an apparatus as an embodiment of the present invention, FIG. 2 is a diagram for explaining conventional information compression, and FIG. 3 is a band according to the embodiment shown in FIG. 4A and 4B are views for explaining the compression, FIGS. 4A and 4B are diagrams schematically showing a processed signal form in the apparatus of this embodiment, and FIG. 5 is a diagram of the signal conversion circuit in FIG. FIG. 6 is a diagram showing a specific example, FIG. 6 is a diagram showing a recording format on a recording medium according to this embodiment, FIG. 7 is a diagram showing a reproducing system of an apparatus as one embodiment of the present invention, and FIG. FIG. 9 is a diagram showing a specific example of the signal conversion circuit in FIG. 7. E is a recording pixel in a mode without band compression, C is a recording pixel in a mode with band compression, 4 is a memory,
5 is a C mode data generation circuit, 6 is a mode determination circuit, 7
Is a switch, 17 is a magnetic head, 18 is a magnetic tape, 37 is a memory, 38 is an address control circuit, 45 is a C mode interpolation circuit,
Reference numeral 52 is a memory, and 53 is an address and timing control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masahiro Takei Inventor Masahiro Takeno, 770, Shimonoge, Takatsu-ku, Kawasaki Canon Inc. Tamagawa Plant (56) References JP-A-60-65693 (JP, A)

Claims (1)

(57) [Claims] 1. An apparatus for recording image information obtained by compressing each pixel block consisting of a predetermined number of pixels while forming a recording track on a recording medium, and an original image based on the image information. Main image information that can restore information or image information other than the main image information that can be used together with main image information to restore the original image information is generated, and the image information of each block other than the main image information The recording means for compressing the image information obtained from the compressing means on the recording medium, the compressing means compressing at a different compression rate for each block depending on whether the image information is included or not. Is an image signal recording apparatus, wherein only the main image information is recorded in a specific area in the recording track.