Image processing apparatus

An image processing apparatus includes an image pickup circuit having a plurality of photographic modes, such as television standards, a compression processing circuit for performing compression processing of an image pickup signal outputted from the image pickup circuit, the compression circuit having a plurality of compression modes, and a selecting circuit for selecting one of the compression modes of the compression processing circuit in accordance with a selected one of the photographic modes of the image pickup circuit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an image processing apparatus including an 
image pickup system and compression processing means for compressing a 
photographic image obtained from the image pickup system. 
2. Description of the Related Art 
FIG. 1 is a schematic block diagram showing the arrangement of a 
conventional example in which a video camera is integrated with a digital 
video tape recorder for digitally recording a video signal. 
In the example shown in FIG. 1, an image pickup device 10 is provided with 
a complementary color filter and performs pseudo-interlaced reading of 
electric charge stored by field storage. Specifically, as shown in FIG. 2, 
the image pickup device 10 is provided with a mosaic color filter made up 
of filter elements: white (W), cyan (Cy), yellow (Ye) and green (G). The 
image pickup device 10 outputs the added values of two adjacent upper and 
lower lines, and a luminance signal processing circuit 12 adds together 
the values of two adjacent pixels contained in the output of the image 
pickup device 10, thereby forming a luminance signal. A chrominance signal 
processing circuit 14 obtains differences between the values of the two 
adjacent pixels, thereby forming color-difference signals. 
More specifically, a luminance signal Yn obtained from a line #n and a 
luminance signal Yn+1 obtained from a line #(n+1) are as follows: 
EQU Yn=(W+Cy)+(G+Ye) 
EQU Yn+1=(W+Ye)+(G+Cy) 
and the associated chrominance signals Cn and Cn+1 are as follows: 
EQU Cn=(W+Cy)-(G+Ye) 
EQU Cn+1=(W+Ye)-(G+Cy) 
If the characteristic of each filter element W is equal to the sum of R 
(red), G (green) and B (blue), i.e., R+G+B; the characteristic of each 
filter element Cy is equal to B+G; and the characteristic of each filter 
element Ye is equal to Ye=R+G, the following equations are obtained: 
EQU Yn=Yn+1=2R+4G+2B 
EQU Cn=2(B-G) 
EQU Cn+1=2(R-G) 
As shown in FIG. 2, the line numbers of adjacent upper and lower lines to 
be added together are made to differ between an even field and an odd 
field, whereby an interlaced signal is obtained. To perform this addition, 
the image pickup device 10 needs to be provided with a photoelectric 
conversion element having lines the number of which is equivalent to the 
number of lines per frame (in the NTSC system, 525 lines). In the case of 
the NTSC system, in a line Lm of the image pickup device 10 shown in FIG. 
1, m is 525. 
A luminance signal Y formed by the luminance signal processing circuit 12 
and a chrominance signal C formed by the chrominance signal processing 
circuit 14 are stored in an image memory 16 under the control of a memory 
control circuit 18. When image data for one frame are stored in the image 
memory 16, a motion detecting circuit 20 discriminates between a moving 
image portion and a still image portion. An image compressing circuit 22 
compresses the image data supplied from the image memory 16, by using 
correlations present in the image. At this time, the image compressing 
circuit 22 adaptively switches compression algorithms between the still 
image portion and the moving image portion in accordance with the 
detection result provided by the motion detecting circuit 20. 
The compressed image data is applied to an image recording device 24, and 
the image recording device 24 records the compressed image data on a 
recording medium. 
A system control circuit 26 controls the entire arrangement in accordance 
with the operation of a key operation device 28. 
In the above-described arrangement, pseudo-interlaced field images are 
compressed and recorded on the recording medium. 
In the conventional example in which compression processing is performed 
after field images are combined into a frame image, there is the problem 
that if field images of a fast moving subject are combined into a frame 
image, the resultant image may be blurred as shown in FIGS. 3(a) to 3(c). 
FIG. 3(a) shows an odd field image, FIG. 3(b) shows the succeeding even 
field image, and FIG. 3(c) shows the frame image obtained by combining the 
odd and even field images. 
Compression of an image utilizes correlations which appear in the image in 
the space and time-axis directions thereof. In general, a frame picture 
the vertical line-to-line distance of which is smaller than that of a 
field picture contains higher correlations. For this reason, as described 
above, the conventional example adopts the compression method of 
adaptively switching compression algorithms between a still image portion 
and a moving image portion in a frame image. 
As a result, the conventional example necessarily needs a motion detecting 
circuit for detecting a still image portion and a moving image portion, 
and, in addition, a substantially high detection accuracy is needed. This 
problem makes it difficult to reduce the size of the circuit. 
As is known to those skilled in the art, since a conventional 
camera-integrated type of VTR does not conform to a plurality of 
television standards, a plurality of camera-integrated types of VTRs must 
be prepared and selectively used according to individual purposes. With 
the diversification of broadcasting systems, it becomes far more necessary 
to exchange program software tapes between different nations or to produce 
software conforming to multiple broadcasting systems. However, if a 
plurality of broadcasting systems are to be handled, a plurality of 
existing VTRs are needed, so that practical inconveniences will be 
encountered. For this reason, it has been desired to provide a VTR unit 
capable of conforming to multiple broadcasting systems. 
As is also known to those skilled in the art, systems for recording and 
reproducing a digitized video signal are individually designed according 
to necessary image qualities or recordable/reproducible data rates. 
However, if system designs differ in coding sampling frequency which is a 
primary parameter for determining image quality, when one system is 
connected to another video system, various problems occur. 
Such conventional systems which are separately designed according to 
individual required image qualities have the problem that it is impossible 
to readily exchange image data between systems via media. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide an image 
processing apparatus capable of solving the above-described problems. 
To achieve the above object, in accordance with one aspect of the present 
invention, there is provided an image processing apparatus which comprises 
image pickup means having a plurality of photographic modes, compression 
processing means for performing compression processing of an image pickup 
signal outputted from the image pickup means, the compression means having 
a plurality of compression modes, and selecting means for selecting one of 
the compression modes of the compression processing means in accordance 
with a selected one of the photographic modes of the image pickup means. 
According to the above arrangement, it is possible to fully utilize the 
performance of the compression processing means, so that it is possible to 
realize a good image quality and a high compression ratio. 
Another object of the present invention is to provide a video recording 
apparatus, a video reproducing apparatus and a video recording and 
reproducing apparatus, such as a multimode-capable camera-integrated type 
VTR capable of effecting camera photography, compression signal processing 
and video recording according to a plurality of television standards. 
To achieve the above object, in accordance with another aspect of the 
present invention, there is provided a video recording apparatus which 
comprises image pickup means capable of conforming to a plurality of 
television standards, recording means for compressing data outputted from 
the image pickup means at a compression ratio according to a television 
standard selected from the plurality of television standards and recording 
on a recording medium compressed data and identification information for 
identification of the selected television standard, setting means for 
setting the selected television standards, and controlling means for 
controlling the image pickup means and the recording means in accordance 
with a setting of the setting means. 
To achieve the above object, in accordance with another aspect of the 
present invention, there is provided a video reproducing apparatus which 
comprises reproducing means for reproducing video data compressed 
according to a television standard and identification information for 
identification of the television standard from a recording medium on which 
the video data and the identification information are recorded, and 
performing expansion processing of the video data, and controlling means 
for controlling the reproducing means on the basis of the identification 
information reproduced from the recording medium. 
To achieve the above object, in accordance with another aspect of the 
present invention, there is provided a video recording and reproducing 
apparatus which comprises a system converter for converting a first video 
signal conforming to a first television standard into a second video 
signal conforming to a second television standard, recording means for 
recording the first or second video signal on a recording medium, 
switching means for supplying to the recording means the first video 
signal or the second video signal obtained from the system converter, 
reproducing means for reproducing the first or second video signal from 
the recording medium, and signal supplying means for supplying the first 
video signal reproduced by the reproducing means to the system converter. 
According to the first two aspects of the present invention, with a single 
camera-integrated type VTR, it is possible to automatically perform 
recording processing and reproduction processing according to a plurality 
of compression modes which conform to a plurality of television standards. 
According to the third aspect of the present invention, the system 
converter is used during both recording and reproduction so that it is 
possible to perform recording and reproduction of or provide a monitor 
output of a video signal according to a desired television standard. 
In accordance with another aspect of the present invention which has been 
made to solve the aforesaid problems, there is provided a video system 
which comprises recording means for recording video information, which is 
hierarchically coded, while forming a data recording area on a recording 
medium in accordance with a hierarchical structure of the video 
information and at least one recording mode of a plurality of recording 
modes each having a different recording processing, and reproducing means 
capable of setting a reproduction mode according to the at least one 
recording mode and the hierarchical structure, or reproducing means 
capable of setting a reproduction mode within a range of the hierarchical 
structure irrespective of the at least one recording mode. 
According to the above aspect, it is possible to perform reproduction 
processing for reproducing recorded data from an information recording 
medium which is recorded in one of the plurality of recording modes, in an 
arbitrary reproduction mode in accordance with the conditions of a 
reproduction side. The recorded data is reproduced from only a data 
recording area which corresponds to a necessary information hierarchy 
within information hierarchically recorded on a recorded tape. 
The above and other objects, features and advantages of the present 
invention will become apparent from the following detailed description of 
preferred embodiments of the present invention, taken in conjunction with 
the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present embodiments are based on the arrangement in which the present 
invention is applied to an image processing apparatus capable of coping 
with a plurality of photographic modes or television standards, as well as 
of performing recording and reproduction processings on hierarchically 
coded video signals. 
Each of the embodiments of the present invention will be described below 
with reference to the accompanying drawings. 
FIG. 4 is a schematic block diagram showing the arrangement of an image 
processing apparatus according to one embodiment of the present invention. 
An image pickup device 30 is capable of selectively performing a field 
reading operation and a frame reading operation, and the color-filter 
arrangement of the image pickup device 30 is identical to that of the 
image pickup device 10 shown in FIG. 1. Although the image pickup device 
10 is arranged to output the results of additions of the respective pairs 
of adjacent lines, the image pickup device 30 of this embodiment is 
capable of independently outputting a charge signal from each pair of 
adjacent lines, as shown in FIG. 5. The field reading operation and the 
frame reading operation of the image pickup device 30 primarily differ in 
reading frequency, and switching between the field reading operation and 
the frame reading operation is performed by a scanning switching circuit 
32. 
An even line processing circuit 34 computes charge signals read from the 
even lines of the image pickup device 30, with respect to all the adjacent 
pixels, thereby forming a luminance signal Ye of an even field. An odd 
line processing circuit 36 computes charge signals read from the odd lines 
of the image pickup device 30, with respect to all the adjacent pixels, 
thereby forming a luminance signal Yo of an odd field. Also, a chrominance 
signal processing circuit 38 performs addition of the charge signals read 
from the even and odd lines of the image pickup device 30, with respect to 
all the adjacent lines, as well as subtraction of the same charge signals 
with respect to all the adjacent pixels, thereby a chrominance signal C. 
Specifically, a luminance signal Yn obtained from a line #n of the odd 
field and a luminance signal Yn+1 obtained from a line #(n+1) are as 
follows: 
EQU Yn=W+G 
EQU Yn+1=Cy+Ye 
and the associated chrominance signals Cn and Cn+1 are as follows: 
EQU Cn=(W+Cy)-(G+Ye) 
EQU Cn+1=(W+Ye)-(G+Cy) 
If the characteristic of each filter element W is equal to the sum of R 
(red), G (green) and B (blue), i.e., R+G+B; the characteristic of each 
filter element Cy is equal to B+G; and the characteristic of each filter 
element Ye is equal to Ye=R+G, the following equations are obtained: 
EQU Yn=Yn+1=R+2G+B 
EQU Cn=2(B-G) 
EQU Cn+1=2(R-G) 
Regarding the even field as well, luminance signals and chrominance signals 
can be obtained through similar computations. 
Photoelectrically converted signals, which have been obtained from lines Ll 
to Lm (m=525 in the NTSC system) corresponding to horizontal scanning 
lines which constitute a television picture, are applied to the even line 
processing circuit 34, the odd line processing circuit 36 and the 
chrominance signal processing circuit 38, and the luminance signal Ye and 
the luminance signal Yo as well as the chrominance signal C which is 
common to the signals Ye and Yo are formed. 
A frame photographic image outputted from the image pickup device 30 is 
stored in an image memory 42 in the following manner. The image pickup 
device 30 outputs the photoelectrically converted signals of all the lines 
in the order of the lines, or simultaneously outputs the respective 
photoelectrically converted signals of the even lines and the odd lines in 
line order. Since a switch 44 is open, the luminance signal Ye formed by 
the even line processing circuit 34 passes through an adder 40 without 
being subject to addition, and is applied to the image memory 42. The 
luminance signal Yo formed by the odd line processing circuit 36 and the 
chrominance signal C formed by the chrominance signal processing circuit 
38 are also applied to the image memory 42. The image memory 42 stores the 
luminance signals Ye and Yo and the chrominance signal C under the control 
of a memory control circuit 46. Thus, a frame image obtained by one 
exposure cycle is stored in the image memory 42. The above-described 
operation is hereinafter referred to as the "frame image pickup mode". 
The operation of combining field photographic images obtained by the image 
pickup device 30 to form a frame image and storing the resultant frame 
image in the image memory 42 is performed in the following manner. The 
image pickup device 30 outputs the photoelectrically converted signals of 
all the lines in the order of the lines, or simultaneously outputs the 
respective photoelectrically converted signals of the even lines and the 
odd lines in line order. In this reading stage, image data for an odd 
field is first stored in the image memory 42. Specifically, the image 
memory 42 stores the luminance signal Yo of the odd field which is formed 
by the odd line processing circuit 36 as well as the chrominance signal C 
formed by the chrominance signal processing circuit 38. 
During the next field, the switch 44 is closed and the image memory 42 is 
made to operate in a read modify write mode, thereby feeding the stored 
luminance signal Yo back to the adder 40 through the switch 44. Similarly 
to the aforesaid odd field, the image pickup device 30 outputs the 
photoelectrically converted signals of all the lines in the order of the 
lines, or simultaneously outputs the respective photoelectrically 
converted signals of the even lines and the odd lines in line order. In 
this reading stage, the even line processing circuit 34 and the 
chrominance signal processing circuit 38 operate, and the adder 40 adds 
the luminance signal Yo fed back from the image memory 42 to the luminance 
signal Ye formed by the even line processing circuit 34. Thus, it is 
possible to obtain a result similar to the result of two-line addition 
described previously in connection with the conventional example. The 
image memory 42 sequentially stores the output of the adder 40 and the 
output of the chrominance signal processing circuit 38 into predetermined 
memory locations. Thus, a frame image in which the field images obtained 
through two exposure cycles are combined is stored in the image memory 42. 
The above-described operation is referred to as the "field image pickup 
mode". 
When the image data for one frame is stored in the image memory 42, the 
image compressing circuit 48 compresses the image data stored in the image 
memory 42 in a compression mode according to a control signal supplied 
from a system control circuit 52. For example, according to which of the 
frame image pickup mode and the field image pickup mode is active, a block 
to be formed by block coding such as DCT (discrete cosine transform), 
which block is a main unit in image compression processing, is determined 
as a field-based block or a frame-based block. 
The compressed image data outputted from the image compressing circuit 48 
is applied to an image recording device 50, and the image recording device 
50 records the compressed image data on a recording medium. 
The system control circuit 52 controls the entire apparatus in accordance 
with the operation of a key operation device 54. 
As a matter of course, it is also possible to select a compression system 
from among various compression coding systems other than DCT. For example, 
if a DPCM system which is one kind of predictive coding system is 
employed, in the case of the field image pickup mode in which a higher 
correlation appears in a horizontal direction than in a vertical 
direction, compression is performed by a horizontal DPCM system of 
performing a differential computation in the horizontal direction, while, 
in the case of the frame image pickup mode in which a higher correlation 
appears in a vertical direction than in a horizontal direction, 
compression is performed by a vertical DPCM system of performing a 
differential computation in the vertical direction. 
In the above-described embodiment, switching between field-based image 
compression and block-based image compression is performed according to 
which of the field image pickup mode and the frame image pickup mode has 
been selected. However, as a matter of course, it is also possible to 
adopt an arrangement capable of selecting the field image pickup mode or 
the frame image pickup mode in accordance with whether the field-based 
image compression or the frame-based image compression has been selected. 
In other words, it is possible to reduce a degradation of image quality by 
linking the field image pickup mode or the frame image pickup mode with 
the field-based image compression or the frame-based image compression. 
Another embodiment of the present invention will be described below in 
which the present invention is applied to a camera-integrated type video 
recording apparatus which is compatible to an existing broadcasting system 
(for example, the NTSC system (SD)) and a high-definition television 
system (for example, a "high-vision" system (HD)) and of performing camera 
photography, compression processing and recording which is intended to two 
layers of image structures (SD and HD) each having a different 
image-quality design. FIG. 6 is a schematic block diagram of the 
arrangement of the entire apparatus. 
Referring to FIG. 6, an HDTV camera 60 is arranged to output a 
high-definition television signal, i.e., an HD signal. According to a 
television studio standard, the number of effective pixels per picked-up 
image is 1,920 pixels in the horizontal direction and 1,035 pixels in the 
vertical direction, and the sampling frequency is 75.3 MHz. The output of 
the camera 60 enters two different paths. The signal which has entered one 
path is applied to an image pickup mode selecting circuit 64 via a 
broadcasting system conversion circuit 62, while the signal which has 
entered the other paths is directly applied to the image pickup mode 
selecting circuit 64. 
The broadcasting system conversion circuit 62 is a down converter for 
converting an HD signal into a signal conforming to any of the NTSC, 
and SECAM systems which are standard broadcasting systems (hereinafter 
referred to as the "SD system"). 
One example of the broadcasting system conversion circuit 62 for converting 
an HD signal into an NTSC signal is shown in FIG. 7. Since the HD signal 
has an aspect ratio of 16:9 and the SD signal has an aspect ratio of 4:3, 
an aspect ratio conversion circuit 100 converts the 16:9 aspect ratio into 
the 4:3 aspect ratio. 
Specifically, it is possible to select a desired system from among a side 
panel system in which the right and left end portions of a high-vision 
image are omitted (refer to FIG. 8), a squeeze system (or a full-display 
system) in which a high-vision image is compressed in the horizontal 
direction (refer to FIG. 9), and a letter box system in which an image of 
16:9 aspect ratio is displayed in a picture of 4:3 aspect ratio (refer to 
FIG. 10). In the case of the letter box system, although empty spaces are 
formed in the top and bottom portions of a picture, they are displayed in 
black. If the HD signal is to be converted into the NTSC system, the side 
panel system or the squeeze system is suitable, while the letter box 
system is suited to a case where it is desired to fully utilize the 
photographic field angle of the HD camera 60. 
The HD signal and the SD signal greatly differ in the number of horizontal 
scanning lines. A number-of-scanning-lines conversion circuit 102 converts 
the number of horizontal scanning lines of the HD output of the aspect 
ratio conversion circuit 100 into the number of horizontal scanning lines 
conforming to the SD system. For example, signals for the required 
horizontal scanning lines are formed by a vertical interpolation filter. 
A field frequency conversion circuit 104 converts the field frequency of 
the output of the number-of-scanning-lines conversion circuit 102 (60 HZ 
in the case of the high-definition signal) into a field frequency 
conforming to the SD system (59.94 Hz in the case of the NTSC system). 
This frequency conversion can be executed at real time by a time-base 
corrector having a function similar to a frame synchronizer. 
In a generally used frame synchronizer, in the case of a capacity of one 
frame memory, one frame cap occurs at intervals of approximately 33 
seconds and causes an unnatural discontinuity in a moving image. In 
contrast, motion-adaptive type field frequency conversion detects motions 
and scene changes by using a frame difference signal, and performs frame 
skipping if the following four conditions are satisfied: 
1) an image signal indicates a still image; 
2) a scene change has occurred; 
3) a moving-image area is comparatively small; and 
4) a frame buffer memory is full. 
An NTSC encoder 106 converts the output of the field frequency conversion 
circuit 104 into a television signal conforming to the NTSC system. 
In the present embodiment, in the case of the SD system as well, it is 
possible to select a high image quality mode for business use (horizontal 
resolution: approximately 450 lines) and a standard image quality mode for 
home use (horizontal resolution: approximately 230 lines). The former mode 
is hereinafter referred to as the "SD-High mode", while the latter mode is 
hereinafter referred to as the "SD-Low mode". A mode for recording the HD 
signal is hereinafter referred to as the "HD mode". An operator can 
selectively set the HD mode, the SD-High mode or the SD-Low mode by means 
of an operation panel 92, and a system control circuit 90 controls the 
image pickup mode selecting circuit 64 in accordance with the mode set by 
the operator. The image pickup mode selecting circuit 64 selects the HD 
signal output of the camera 60 in the case of the HD mode or the output of 
the broadcasting system conversion circuit 62 in the case of the SD-High 
mode or the SD-Low mode. 
The signal selected by the image pickup mode selecting circuit 64 is 
applied to a compression circuit 66. The compression circuit 66 is 
provided with a plurality of compression modes (in the shown example, a 
mode #1 and a mode #2) so that a compression ratio and a compression 
coding system can be individually selected. The compression ratio is 
selected from among, for example, 1/4, 1/8, 1/16 and 1/32. The compression 
coding system is selected from, for example, DCT, DPCM, Hadamard transform 
and ADRC. In the arrangement shown in FIG. 6, for example, DCT and DPCM 
may be allocated to the compression mode #1 and the compression mode #2, 
respectively, or the compression ratio may be varied under a single 
compression coding system. 
The compression circuit 66 compresses the output of the image pickup mode 
selecting circuit 64 in the compression mode #1 as well as in the 
compression mode #2. The data compressed in the compression mode #1 and 
the compression mode #2 are both applied to a compression mode selecting 
circuit 68. The compression mode selecting circuit 68 selects either one 
of the data compressed in the compression mode #1 and the data compressed 
in the compression mode #2, in accordance with a control signal supplied 
from the system control circuit 90, and applies the selected compressed 
data to a recording processing circuit 70. 
The modes to be selected by the image pickup mode selecting circuit 64 and 
the compression mode selecting circuit 68 are closely related to factors, 
such as a recording time or image quality to be selected for a recording 
system and the quality of an image to be picked up by the camera 60 or a 
mode set for the camera 60. The modes are automatically determined in 
association with such factors. 
According to a relationship with a recording system which will be described 
later, it is desirable that the data rates of images compressed in the 
respective compression modes have a relationship represented by an integer 
ratio, for example, 50 Mbps in the HD mode, 25 Mbps in the SD-High mode 
and 12.5 Mbps in the SD-Low mode, as shown in FIG. 22. 
A recording processing circuit 70 applies recording processing, such as 
modulation, to the compressed data supplied from the compression mode 
selecting circuit 68, divides the processed data into two channels, and 
outputs the divided data to the respective channels. Recording amplifiers 
72a and 72b amplify the respective outputs of the recording processing 
circuit 70. A rotary drum 74 is provided with two pairs of heads 76a, 76b 
and 78a, 78b. The outputs of the recording amplifiers 72a and 72b are 
respectively recorded on a magnetic tape 80 by the heads 76a, 76b and 78a, 
78b. The width of each track formed on the magnetic tape 80 is the same 
for any of the HD mode, the SD-High mode and the SD-Low mode. 
A servo circuit 82 causes a drum motor 84 to rotate the rotary drum 74 at a 
predetermined rotational speed, and also causes a capstan motor 86 to 
rotate a capstan 88, thereby causing the magnetic tape 80 to run at a 
predetermined speed. The system control circuit 90 supplies to the servo 
circuit 82 a target value based on an operation mode according to an 
operation instruction inputted through the operation panel 92. 
FIG. 11 shows the relationships between the modes selected through the 
operation panel 92 and the image pickup systems, the compression ratios 
and the recording data rates. 
The camera 60 shown in FIG. 6 will be described in detail with reference to 
FIG. 12. A photographic lens unit 110 includes a focusing lens 110a for 
adjusting its focal length and a zooming lens 110b for varying its 
magnification, and focuses an optical image of a subject on the 
photoelectric conversion face of an image pickup device 114 via an iris 
112. A predetermined color filter 116 is attached to the photoelectric 
conversion face of the image pickup device 114. 
The image pickup device 114 operates in accordance with a clock supplied 
from a clock generating circuit 118, and outputs a charge signal. The 
output of the image pickup device 114 is noise-reduced by a CDS circuit 
120 and is then gain-controlled by an AGC circuit 122. The output of the 
AGC circuit 122 is applied to an exposure control circuit 124, a focus 
control circuit 126, a white balance adjustment circuit 128 and a color 
processing circuit 130. 
A driving circuit 132a and a motor 132b drive the focusing lens 110a along 
the optical axis, a driving circuit 134a and a motor 134b drive the 
zooming lens 110b along the optical axis, and a driving circuit 136a and a 
motor 136b drive the iris 112 to cause it to open and close. 
A system control circuit 138 controls the gain of the AGC circuit 122 in 
accordance with the output of the exposure control circuit 124, and also 
controls the degree of opening of the iris 112 by means of the driving 
circuit 136a and the motor 136b. The system control circuit 138 adjusts 
the position of the focusing lens 110a along the optical axis by means of 
the driving circuit 132a and the motor 132b in accordance with the output 
of the focus control circuit 126, thereby placing the photographic lens 
unit 110 into an in-focus state. 
The white balance adjustment circuit 128 forms a control signal for white 
balance adjustment, and the system control circuit 138 controls the color 
processing circuit 130 in accordance with the output of the white balance 
adjustment circuit 128. The color processing circuit 130 generates a 
white-balanced luminance signal Y as well as color-difference signals R-Y 
and B-Y from the output of the AGC circuit 122. A process circuit 140 
converts into RGB signals the luminance signal Y and the color-difference 
signals R-Y and B-Y outputted from the color processing circuit 130, and 
an encoder 142 generates a composite signal from the output of the process 
circuit 140. The encoder 142 also outputs video signals in Y/C separation 
form. 
The outputs of the color processing circuit 130 and the outputs of the 
process circuit 140 may of course be outputted to the outside as component 
outputs. 
A display generating circuit 144 generates display signals indicative of 
operation mode, time and date and the like under the control of the system 
control circuit 138, and an adder 146 adds the output of the display 
generating circuit 144 to the composite output of the encoder 142 and 
applies a signal indicative of the addition result to an electronic 
viewfinder 148. Thus, a photographer can view various kinds of information 
together with a subject to be photographed, on the screen of the 
electronic viewfinder 148. Further, since a composite signal is inputted 
to the electronic viewfinder 148 from a reproducing system which will be 
described later, it is possible to view a reproduced image. 
The photographer also can set photographic conditions, such as photographic 
mode, photographic magnification and exposure, by operating an operation 
key 150. 
If photographic image information is digitally processed in the camera 
shown in FIG. 12, each output signal may of course be outputted in digital 
form. If analog outputs are needed, a D/A converter and a band-limiting 
low-pass filter may be provided at suitable locations. 
The compression processing performed in the compression circuit 66 shown in 
FIG. 6 will be described below in brief. Compression of an image is to 
reduce the amount of data by removing the redundancy of the image. 
Compression of a still image utilizes the spatial redundancy of the image. 
Compression of a moving image utilizes its temporal redundancy in addition 
to its spatial redundancy, but the basic principles are based on still 
image compression techniques. 
The element techniques of moving-image compression which conforms to, for 
example, the MPEG (Moving Picture Expert Group) standard, are DCT 
(discrete cosine transform) processing, quantization processing, coding 
processing and motion adaptation processing. Expansion can be regarded as 
the inverse process of compression. The DCT (discrete cosine transform) 
processing, the quantization processing and the coding processing are 
common to both the moving-image compression and still-image compression. 
These techniques will be described below in brief in that order. 
DCT converts spatial coordinates into frequencies. As the pre-processing of 
compression, an input picture is blocked into a pixel group of 
approximately 8.times.8 pixels. Multiplication processing using DCT 
coefficients is performed in units of blocks, whereby space data are 
converted into frequency data. Although the amount of data is not reduced 
by DCT alone, it is possible to concentrate data which is widely dispersed 
in the picture. In other words, an image has a general tendency for more 
energy to concentrate on a lower spatial frequency side, and DCT performs 
the function of increasing a compression ratio for substantial compression 
processing to be executed at the succeeding stages. 
The quantization processing rounds off the word lengths of coefficients 
which have been converted into frequencies by the DCT processing, thereby 
reducing the amount of data. For example, a data coefficient indicative of 
each frequency component produced by DCT is divided by an appropriate 
value, and the figures below the decimal point of the resultant value are 
omitted. By omitting the figures below the decimal point, it is possible 
to reduce the number of bits which are required to represent each 
coefficient data, whereby the total amount of data can be reduced. By 
setting a divisor for each frequency component, it is possible to increase 
the compression ratio while retaining the required image quality. 
The coding processing assigns to each data a length code corresponding to 
the occurrence frequency of the data. First, a zigzag scan of the 
quantized data is performed to convert a two-dimensional data array into a 
unidimensional data string. The two-dimensional data array is scanned in a 
zigzag manner from a DC component toward horizontal and vertical 
higher-frequency components, whereby the data is rearranged. By run length 
coding, the same numbers (mainly, zeros) which continuously occur are 
replaced with one code which collectively represents such continuous 
occurrence. If the data which appear after a particular location are all 
zeros, an end code is assigned to the data. This code indicates that if it 
is detected in a block, the transfer of data from the block is brought to 
an end, and realizes a great, data reduction effect. 
By assigning codes of fewer bits to numbers having higher occurrence 
frequencies, the substantial total number of coding bits can be reduced. 
The motion adaptation processing adds the technique of detecting and 
predicting a motion to still-image compression. The element techniques 
includes motion detection, motion predictive compensation and interlacing 
coding. The motion adaptation processing will be described below with 
illustrative reference to the case of compression of a moving image 
conforming to a television broadcasting standard. 
In the motion detection, image data is delayed by a time which corresponds 
to an integer multiple of a field (or frame) period, as by a frame memory, 
and two field (frame) pictures are compared in a time-axis direction, 
thereby detecting a motion. As well-known motion detecting methods, there 
are a method of obtaining the amount of motion as the absolute value of 
the difference in luminance data between pictures and a method of 
computing the travel of a two-dimensional coordinate point having a 
highest correlation, thereby detecting a motion vector. 
The motion predictive compensation predicts a motion of an image by the 
detected motion vector and transmits only the difference between a 
predicted image and an actual image as compensation data. Accordingly, it 
is possible to reduce the amount of information to be transferred. 
Specifically, it is possible to reduce prediction errors in the case of 
images, such as an image which contains a large still-image portion and 
moves to a small extent, an image which moves moderately and an image 
which is rectilinearly travelling. Accordingly, a high compression effect 
can be achieved. 
The interlacing coding forms a pixel block for compression processing in 
units of fields. A television signal, such as an NTSC television signal, 
has an interlaced structure in which the scanning lines of odd and even 
fields are alternately disposed. An odd field made up of 262.5 odd lines 
and an even field made up of 262.5 even lines are paired to form a frame 
picture made up of 525 lines. 
If an odd field and an even field are simply combined when the amount of 
motion of a subject in a picture is large, a frame image blurs and is 
visually extremely impaired. In a blurred portion of the picture, a 
vertical spatial correlation is lowered, so that no high compression ratio 
can be achieved by compression coding processing. If the amount of motion 
is small, this problems does not occur. 
For this reason, if the amount of motion is small, a pixel block for 
compression processing is formed within a frame picture, while if the 
amount of motion is greater than a predetermined amount, a pixel block for 
compression processing is formed within a field picture. 
FIG. 13 is a schematic block diagram showing the arrangement of an image 
compressing circuit which adopts the above-described moving image 
compression processing techniques. Referring to FIG. 13, an SD or HD 
signal outputted from the image pickup mode selecting circuit 64 shown in 
FIG. 6 is inputted through an input terminal 200. The video signal 
inputted through the input terminal 200 is inputted to an input buffer 202 
and a motion detecting circuit 204. The input buffer 202 functions as 
1-frame-period delay means, and its output is applied to a blocking 
circuit 206 and the motion detecting circuit 204. 
The motion detecting circuit 204 performs the above-described comparison 
computation on the video signal supplied from the input terminal 200 and 
the video signal outputted from the input buffer 202, thereby detecting a 
motion vector. The motion detecting circuit 204 outputs information 
indicative of the amount and direction of the motion to a system control 
circuit 220. On the basis of the motion vector information, the system 
control circuit 220 determines whether compression processing is to be 
performed in units of fields or in units of frames, and applies the 
resultant field/frame selection information to the blocking circuit 206. 
The blocking circuit 206 blocks the output image of the input buffer 202 
into 8 pixels.times.8 pixels as shown in FIG. 14, in the units of fields 
or frames according to the field/frame selection signal supplied from the 
system control circuit 220. FIG. 15 shows the pixel arrangements of odd 
and even fields within one frame. 
A DCT circuit 208 performs discrete cosine transform of the blocked pixel 
data supplied from the blocking circuit 206. By this discrete cosine 
transform, the image data is converted into coefficient data which is 
represented as a block of 8 pixels.times.8 pixels in a frequency space as 
shown in FIG. 16. As the general nature of an image, a DC coefficient and 
lower-frequency AC components have larger values, while higher-frequency 
AC components have values close to zero. 
The output of the DCT circuit 208 is applied to a quantizing circuit 210 
and a coefficient setting circuit 212. The coefficient setting circuit 212 
sets a quantizing coefficient for the quantizing circuit 210 in accordance 
with a control signal supplied from the system control circuit 220 and the 
output of the DCT circuit 208. The quantizing circuit 210 quantizes the 
output of the DCT circuit 208 with the quantizing coefficient set by the 
coefficient setting circuit 212. Specifically, data coefficients for the 
individual frequency components are divided by adequate divisors, and the 
figures below the decimal points of the respective results are omitted to 
reduce the number of bits. Incidentally, the divisors may differ among the 
individual frequency components. 
A coding circuit 214 first performs a zigzag scan of the output of the 
quantizing circuit 210 in the zigzag manner shown in FIG. 17 from a DC 
component toward horizontal and vertical higher-frequency components as 
shown in FIG. 17, thereby unidimensionally rearranging the data. After 
then, the coding circuit 214 replaces continuing zeros with a 
predetermined code indicative of the number of the continuing zeros by run 
length coding. As described previously, if all the data which appear after 
a particular location are zeros, the coding circuit 214 assigns an end 
code to the data. The coding circuit 214 also assigns a short code to data 
the occurrence frequency of which is high, by variable length coding. 
Thus, the amount of data can be greatly reduced. 
An amount-of-data calculating circuit 218 calculates the amount of the 
coded data generated by the coding circuit 214 and supplies the result to 
the system control circuit 220. The system control circuit 220 causes the 
coefficient setting circuit 212 to generate a quantizing coefficient which 
is selected so that the amount of coded data to be generated by the coding 
circuit 214 becomes a predetermined value. 
The output of the coding circuit 214 is supplied to an output buffer 216. 
The output buffer 216 supplies the output of the coding circuit 214 to a 
rear-stage circuit at a data rate. The output buffer 216 also supplies 
information indicative of its internal data occupation ratio to the system 
control circuit 220. The system control circuit 220 controls the 
coefficient setting circuit 212 so that this occupation ratio becomes 
stable in the neighborhood of a predetermined value in order to prevent an 
overflow or a data shortage from occurring in the output buffer 216. 
Specifically, if the data occupation ratio is high, the system control 
circuit 220 causes the coefficient setting circuit 212 to set a large 
coefficient (divisor), whereas if the data occupation ratio is low, the 
system control circuit 220 causes the coefficient setting circuit 212 to 
set a small coefficient (divisor). 
In the arrangement shown in FIG. 13, the system control circuit 220 
controls the coefficient setting circuit 212 in accordance with the amount 
of coded data generated by the coding circuit 214 (the output of the 
amount-of-data calculating circuit 218) and the data occupation ratio of 
the output buffer 216. An operator can instruct, through a mode selecting 
member 222, the system control circuit 220 to perform switching among the 
compression ratios (target values), the compression systems and the like. 
Of course, the system control circuit 220 can adaptively control the 
compression ratios (target values), the compression systems and the like 
in accordance with the result of the detection of a motion of an image and 
an operation-mode set by the mode selecting member 222, whereby it is 
possible to efficiently compress a moving image. As a matter of course, by 
changing the coefficient to be set by the coefficient setting circuit 212, 
it is also possible to vary the compression ratio. 
The recording system for recording a signal supplied from the camera system 
of FIG. 12 will be described below in detail. FIG. 18 is a detailed block 
diagram showing the arrangement of the recording system. In the shown 
arrangement, a system control circuit 336 is substantially identical to 
the system control circuit 138 of the camera system. 
An A/D converter 300 converts the luminance signal Y into a digital signal, 
while an A/D converter 302 converts the chrominance signal C into a 
digital signal. The luminance signal Y and the chrominance signal C are 
those supplied from the camera system described previously with reference 
to FIG. 12. Of course, if digital processing is already performed in the 
camera system, neither of the A/D converters 300 and 302 is needed. 
A multiplexer 306 of a video data processing circuit 304 multiplexes the 
outputs of the A/D converters 300 and 302 and outputs the multiplexed data 
to an amount-of-information compressing circuit 308. The 
amount-of-information compressing circuit 308 compresses the multiplexed 
data by using a compression system and a compression ratio according to 
mode information supplied from the system control circuit 336. The 
amount-of-information compressing circuit 308 is substantially identical 
to the circuit described above with reference to FIG. 13. Of course, it is 
also possible to adopt a circuit arrangement for individually compressing 
the amounts of information of luminance data and chrominance data without 
multiplexing these data in the multiplexer 306. 
A shuffling circuit 310 rearranges the output data string of the 
amount-of-information compressing circuit 308 in accordance with 
appropriate rules, thereby preventing a transmission error from easily 
occurring in the data string. This shuffling operation also has the effect 
of making uniform the uneven distribution of the amount of information in 
a picture which is based on the presence of dense and sparse portions in 
the picture. The execution of the shuffling operation at a stage preceding 
the compression of the amount of information is convenient for variable 
length coding, such as run length coding. 
An ID adding circuit 312 adds identification (ID) information for restoring 
the data shuffled by the shuffling circuit 310. This identification 
information also contains mode information indicative of modes used for 
recording (the kind of compression system and the like), and is used as 
auxiliary information for expansion processing during reproduction. An ECC 
adding circuit 314 adds an error-correcting code to the output data of the 
ID adding circuit 312. 
The video data subjected to the above-described processing in the video 
data processing circuit 304 is distributed into two channels by a data 
distributing circuit 316. 
An A/D converter 318 converts the L-channel signal of a stereophonic audio 
signal into a digital signal, while an A/D converter 320 converts the 
R-channel signal into a digital signal. A multiplexer 324 of an audio data 
processing circuit 322 multiplexes the outputs of the A/D converters 318 
and 320 and outputs the multiplexed data to an amount-of-information 
compressing circuit 326. The amount-of-information compressing circuit 326 
compresses the multiplexed data by using a compression system and a 
compression ratio according to mode information supplied from the system 
control circuit 336. 
If the recording rate of video data is large, as in the case of an HD 
signal, audio information may also be recorded on a recording medium 
without compression. 
A shuffling circuit 328 rearranges the output data string of the 
amount-of-information compressing circuit 326 in accordance with 
appropriate rules, thereby preventing a transmission error from easily 
occurring in the data string. An ID adding circuit 330 adds identification 
(ID) information for restoring the data shuffled by the shuffling circuit 
328. This identification information also contains mode information 
indicative of modes used for recording (the kind of compression system and 
the like), and is used as auxiliary information for expansion processing 
during reproduction. An ECC adding circuit 332 adds an error-correcting 
code to the output data of the ID adding circuit 330. 
The audio data subjected to the above-described processing in the audio 
data processing circuit 322 is distributed into two channels by a data 
distributing circuit 334. 
A pilot generating circuit 338 generates a pilot signal for tracking servo, 
and a sub-code generating circuit 340 generates auxiliary data to be 
recorded simultaneously with the video and audio data. Such auxiliary data 
contains, for example, an address code for searching for a position on a 
magnetic tape and the indexes of a program to be recorded. 
A multiplexer 342 multiplexes one of the channel outputs of each of the 
data distributing circuits 316 and 334, the pilot signal outputted from 
the pilot generating circuit 338, and the sub-code data generated by the 
sub-code generating circuit 340. A multiplexer 344 multiplexes the other 
channel output of each of the data distributing circuits 316 and 334, the 
pilot signal outputted from the pilot generating circuit 338, and the 
sub-code data generated by the sub-code generating circuit 340. In the 
case of time-base multiplexing, the multiplexing of the pilot signal may 
be performed in accordance with an area division ATF system which is well 
known in the field of digital audio tape recorders. 
Digital modulating circuits 346 and 348 digitally modulate the respective 
outputs of the multiplexers 342 and 344 by means of, for example, 8-10 
conversion and an NRZI method. 
The recording system according to the present embodiment is provided with 
two pairs of magnetic heads. A head switching circuit 350 switches the 
output of the modulating circuit 346 between recording amplifiers 354 and 
356 in accordance with a control signal supplied from a servo circuit 378. 
A head switching circuit 352 switches the output of the modulating circuit 
348 between recording amplifiers 358 and 360 in accordance with a control 
signal supplied from the servo circuit 378. The outputs of the recording 
amplifiers 354, 356, 358 and 360 are respectively applied to magnetic 
heads 364a, 364c, 364b and 364d of a rotary drum 362, whereby they are 
recorded on a magnetic tape 366. FIG. 19 shows one example of the track 
pattern of the magnetic tape 366. Each of the tracks contains a pilot 
signal P, audio data A, sub-code S and video data V. FIG. 20 shows the 
detailed data structure of the sub-code S. 
The servo circuit 378 controls the rotation of the rotary drum 362 and the 
running of the magnetic tape 366 as well as the head switching operations 
of the head switching circuits 350 and 352. Specifically, a rotation 
detector (FG) 376 for detecting the rotation of a capstan motor 374 for 
causing the magnetic tape 366 to run is connected to the capstan motor 
374, and the servo circuit 378 controls, according to the output of the 
rotation detector (FG) 376, the capstan motor 374 to cause it to rotate at 
a predetermined rotational speed. 
Also, a drum motor 368 rotates the rotary drum 362, a rotation detector 
(FG) 370 detects the rotational speed of the drum motor 368, and a 
rotational phase detector (PG) 372 detects the rotational phase of the 
rotary drum 362. The servo circuit 378 drives, according to the outputs of 
the rotation detector (FG) 370 and the rotational phase detector (PG) 372, 
the drum motor 368 to cause the rotary drum 362 to rotate at a 
predetermined rotational speed. The servo circuit 378 also controls the 
head switching operations of the head switching circuits 350 and 352 in 
accordance with the output of the rotational phase detector (PG) 372. 
The system control circuit 336 controls the entire recording system in 
accordance with an instruction inputted through an operation panel (not 
shown) and on the basis of the operating state of each part. 
The functions of the system control circuit 336 and the servo circuit 378 
are realized by one microcomputer chip. 
The reproducing system will be described below in detail with reference to 
FIG. 21. In FIG. 21, identical reference numerals are used to denote 
constituent elements identical to those shown in FIG. 18. Specifically, in 
a manner similar to the recording operation, the servo circuit 378 causes 
the magnetic tape 366 to run at a predetermined speed by means of the 
capstan motor 374 as well as causes the rotary drum 362 to rotate at a 
predetermined rotational speed and in a predetermined rotational phase by 
means of the capstan motor 374. 
The outputs of the magnetic heads 364a, 364c, 364b and 364d are 
respectively amplified by reproducing amplifiers 380, 382, 384 and 386, 
and the outputs of the reproducing amplifiers 380, 382 and 384, 386 are 
respectively applied to head switching circuits 388 and 390. In accordance 
with control signals supplied from the servo circuit 378, the head 
switching circuit 388 switches the outputs of the reproducing amplifiers 
380 and 382 therebetween, while the head switching circuit 390 switches 
the outputs of the reproducing amplifiers 384 and 386 therebetween. 
Demodulating circuits 392 and 394 respectively digitally demodulate the 
outputs of the head switching circuits 388 and 390 by a redundancy 
detecting method, such as a differential detecting method, an integral 
detecting method or Viterbi decoding, and output two-level signals. Each 
of the outputs of the demodulating circuits 392 and 394 is made of 
information which includes video information, audio information, a pilot 
signal and sub-code information in a time division multiplexed state. 
Signal distributing circuits 396 and 398 supply the respective outputs of 
the demodulating circuits 392 and 394 to predetermined circuits: that is 
to say, the video information is supplied to a data integrating circuit 
406, the audio information is supplied to a data integrating circuit 424, 
the pilot signals are supplied to a pilot detecting circuit 400, and the 
sub-code information is supplied to a sub-code detecting circuit 402. 
The pilot detecting circuit 400 detects as an error signal the time 
difference between the pilot signal and a timing reference signal 
corresponding to an off-track amount relative to the right and left 
tracks, and supplies the error signal to the servo circuit 378. The servo 
circuit 378 adjusts a tape transporting speed in accordance with the error 
signal. The error signal can also be used as auxiliary information for 
identification of a recording mode. 
A sub-code detecting circuit 402 decodes the content of the sub-code from 
each of the S outputs of the signal distributing circuits 396 and 398, and 
supplies the result to a system control circuit 404. The system control 
circuit 404 controls each part in accordance with the content of the 
reproduced sub-code. 
The data integrating circuit 406 integrates the video information supplied 
from the signal distributing circuits 396 and 398 via two lines, and 
outputs the integrated video information to a video data reproducing 
circuit 408. 
In the video data reproducing circuit 408, an error correcting circuit 410 
corrects an error which has occurred during recording or reproduction. If 
the error cannot be corrected, the error correcting circuit 410 performs 
correction of the error by using interpolation. An ID detecting circuit 
412 detects the ID added by the ID adding circuit 312 during recording, 
and supplies the ID to the system control circuit 404. A de-shuffling 
circuit 414 restores the data string rearranged by the shuffling circuit 
310, and an amount-of-information expanding circuit 416 expands the data 
compressed by the amount-of-information compressing circuit 308, in 
accordance with the mode information supplied from the system control 
circuit 404, thereby restoring the original image data. A data separating 
circuit 418 separates the original image data into luminance data and 
chrominance data and supplies the respective data to D/A converters 420 
and 422. The data separating circuit 418 also outputs the digital image 
data to the outside. 
The D/A converter 420 converts the luminance data into an analog signal, 
while the D/A converter 422 converts the chrominance data into an analog 
chrominance signal. The analog signals are both outputted to the outside, 
and are also converted into a composite signal, which is inputted to the 
adder 146 of FIG. 12. An operator can view a reproduced image in the 
electronic viewfinder 148. 
The data integrating circuit 424 integrates the audio information supplied 
from the signal distributing circuits 396 and 398 via two lines, and 
outputs the integrated audio information to an audio data reproducing 
circuit 426. 
In the audio data reproducing circuit 426, an error correcting circuit 428 
corrects an error which has occurred during recording or reproduction. If 
the error cannot be corrected, the error correcting circuit 428 performs 
correction of the error by using interpolation. An ID detecting circuit 
430 detects the ID added by the ID adding circuit 330 during recording, 
and supplies the ID to the system control circuit 404. A de-shuffling 
circuit 432 restores the data string rearranged by the shuffling circuit 
328, and an amount-of-information expanding circuit 434 expands the data 
compressed by the amount-of-information compressing circuit 326, in 
accordance with the mode information supplied from the system control 
circuit 404, thereby restoring the original audio data. A data separating 
circuit 436 separates the original audio data into L-channel audio data 
and R-channel audio data and supplies the respective data to D/A 
converters 438 and 440. The data separating circuit 436 can also output 
the digital audio data to the outside. 
The D/A converter 438 converts the L-channel audio data into an analog 
signal, while the D/A converter 440 converts the R-channel audio data into 
an analog signal. The analog signals are both outputted to the outside. 
As described previously, the present embodiment is provided with the three 
modes: the HD mode, the SD-High mode and the SD-Low mode. Since recording 
track patterns differ among the three modes, mode identification 
information is recorded in sub-code areas so that reproduction from tracks 
can be correctly performed in the case of any of the three modes. The 
recording track patterns and mode identification methods for the 
respective modes will be described below. FIG. 22 shows magnetic tape 
running speeds, the number of tracks per field and compression ratios for 
the respective modes. 
The SD-Low mode serves as a long-time recording mode for the SD signal. Out 
of the four magnetic heads Ha, Hb, Hc and Hd shown in FIG. 23, only the 
magnetic heads Ha and Hb are used, and five tracks per field are formed as 
shown in FIG. 24. FIG. 25 shows the timing of head switching. Recording 
current is alternately applied to the magnetic heads Ha and Hb each time a 
drum PG pulse goes high while a rotary drum is being rotated at 150 rps. 
In the SD-High mode, out of the four magnetic heads Ha, Hb, Hc and Hd shown 
in FIG. 26, only the magnetic heads Ha and Hc are used, and ten tracks per 
field are formed as shown in FIG. 27. FIG. 28 shows the timing of head 
switching. While the rotary drum is being rotated at 150 rps, the 
recording current is applied to the magnetic head Ha if the drum PG pulse 
goes high and to the magnetic head Hc if the drum PG pulse goes low. 
In the HD mode, all the four magnetic heads Ha, Hb, Hc and Hd shown in FIG. 
29 are used, and twenty tracks per field are formed as shown in FIG. 30. 
FIG. 31 shows the timing of head switching. While the rotary drum is being 
rotated at 150 rps, the recording current is applied to the magnetic heads 
Ha and Hb if the drum PG pulse goes high and to the magnetic heads Hc and 
Hd if the drum PG pulse goes low. 
FIG. 32 shows a flowchart of mode identification which is executed during 
reproduction. First, the current reproduction mode is confirmed (S1). In 
Step S2, the flow proceeds to any one of Steps S3, S4 and S5 in accordance 
with the result of the confirmation which indicates any one of the SD-Low 
mode, the SD-High mode and the HD mode. Any value of "5", "10" and "20"is 
set in a variable N (S2, S4 or S5). 
The mode used during recording is identified on the basis of the sub-code 
of a reproduced digital signal (S6 and S7), and the subsequent 
reproduction mode is determined. In Step S7, the flow proceeds to any one 
of Steps S8, S9 and S10 in accordance with the determined mode which is 
any one of the SD-Low mode, the SD-High mode and the HD mode. Any value of 
"5", "10" and "20" is set in a variable M which determines the number of 
tracks per field (S8, S9 or S10). 
The variables N and M are compared (S11). If N&lt;M, the running speed of the 
magnetic tape is increased (S12). If N=M, the running speed of the 
magnetic tape is kept (S13). If N&gt;M, the running speed of the magnetic 
tape is increased (S14). In other words, the running speed of the magnetic 
tape is controlled to become equal to the tape speed specified by a mode 
selected during recording. 
After the completion of Step S12, S13 or S14, the flow returns to Step S1, 
and the above-described processing is repeated. 
An embodiment of a video recording and reproducing apparatus in which the 
down converter shown in FIG. 7 and the up converter shown in FIG. 33 are 
used as broadcasting system converters will be described below with 
reference to FIG. 34 as well. 
FIG. 33 shows one example of an NTSC-HD system converter which serves as 
the up converter. In the NTSC-HD system converter shown in FIG. 33, an 
NTSC signal is decoded through a motion adaptive type NTSC decoder 570, 
and the aspect ratio of the decoded signal is converted from 4:3 to 16:9 
in an aspect ratio conversion part 571. Then, the number of scanning lines 
is converted from 525 to 1,125 in a number-of-scanning-lines conversion 
part 572, and the field frequency is converted from 59.94 Hz to 60 Hz in a 
field frequency conversion part 573. Thus, the NTSC signal is converted 
into an HD signal to be outputted. 
FIG. 34 is a block diagram showing a video recording and reproducing 
apparatus according to another embodiment of the present invention. An 
operator can select recording or reproduction, HD mode or SD mode and the 
like on an operation panel 500. The following description refers to four 
kinds of operations of the recording and reproducing system of the 
apparatus. The input signal of this embodiment is an HD signal. 
(1) Recording in SD Mode (Long-Time Recording Mode) 
"RECORDING" and "SD" are selected on the operation panel 500, and a system 
controller 501 connects the movable contact of a switch 506 to a contact 1 
or 2 thereof. An HD input signal is down-converted into an SD (for 
example, NTSC) signal by a down converter 503. The system controller 501 
also controls a switch 502 to connect the movable contact of the switch 
502 to a contact 1 thereof. Thus, the SD signal is recorded on a tape 510 
through a recording system 509. During this time, an SD monitor 504 is 
used. 
(2) Recording in HD Mode (High Definition Mode) 
"RECORDING" and "HD" are selected on the operation panel 500, and the 
system controller 501 connects the movable contact of the switch 502 to a 
contact 2 thereof. The HD input signal is directly recorded on the tape 
510. During this time, either one of an HD monitor 505 and the SD monitor 
504 can be selected. 
If the HD monitor 505 is to be used, the movable contact of the switch 506 
is connected to the contact 1 or 2 thereof so that the HD signal can be 
directly outputted to the HD monitor 505. 
If the SD monitor 504 is to be used, the movable contact of the switch 506 
is similarly connected to the contact 1 or 2 thereof, and the HD signal is 
down-converted into an SD signal by the down converter 503. By connecting 
the movable contact of the switch 507 to any one selected from the 
contacts 1, 2 and 4 thereof, the SD signal can be outputted to the SD 
monitor 504. 
By adopting the above-described arrangement, it is possible to provide a 
camera-integrated type VTR of reduced size. 
(3) Reproduction in SD Mode 
"REPRODUCTION" and "SD" are selected on the operation panel 500, and the 
system controller 501 connects the movable contact of the switch 507 to a 
contact 3 thereof. An SD signal reproduced from the tape 510 by a 
reproducing system 511 is displayed on the SD monitor 504 as a reproduced 
output image. If the SD signal is to be displayed on the HD monitor 505, 
it is converted into an HD signal by an up converter 508 and the movable 
contact of the switch 506 is connected to a contact 3 thereof. 
(4) Reproduction in HD Mode 
"REPRODUCTION" and "HD" are selected on the operation panel 500, and the 
system controller 501 connects the movable contact of the switch 506 to a 
contact 4 thereof. A reproduced HD signal is directly displayed on the HD 
monitor 505 as a reproduced output image. If the HD signal is to be 
displayed on the SD monitor 504, the movable contact of the switch 506 is 
similarly connected to the contact 4 and the HD signal is converted into 
an SD signal by the down converter 503. When the movable contact of the 
switch 507 is connected to a contact 1 thereof, the SD signal can be 
displayed on the SD monitor 504. The following table shows the manner of 
connection of the contacts 1 to 4 of each of the switches 502, 506 and 507 
during each of the SD and HD modes. 
______________________________________ 
Recording 
Reproduction 
______________________________________ 
SD 1 3 
HD 2 4 
______________________________________ 
Although in the above-described embodiment the up converter 508 is 
employed, a multi-scan monitor may also be used instead of the HD monitor 
505. In the case of the multi-scan monitor, the up converter 508 can be 
omitted because if an SD (for example, NTSC) signal is inputted, the SD 
signal is scanned by using 525 scanning lines/frame. As the SD-Low mode, 
an SD signal having a horizontal resolution of approximately 230 lines 
which is a standard image quality in general domestic apparatus may also 
be applied to the multi-scan monitor. 
As can be readily understood from the above description, in accordance with 
the above-described embodiment, since a compression mode suitable for 
image compression processing to be executed in a recording system is 
selected according to a photographic mode selected in a image pickup 
system, a photographic image can be efficiently compressed by the image 
compression processing, so that good image quality and a high compression 
ratio can be achieved. 
Further, in accordance with the above-described embodiment, in one 
camera-integrated type VTR, it is possible to achieve selective 
utilization of a plurality of camera modes conforming to a plurality of 
broadcasting systems. Also, the setting of a compression mode, such as the 
selection of a compression ratio and a compression system for an image, 
and the setting of the required recording mode in a VTR can be 
automatically controlled by a system controller in accordance with the 
selection of a camera mode. Accordingly, it is possible to realize a 
camera-integrated type VTR which can be utilized in a variety of 
applications by an easy operation without the need to perform a 
complicated connection or operation. 
Also, in accordance with the above-described embodiment, since a single 
down converter is used to perform recording of a video signal input and 
reproduction of a recorded video signal, it is possible to reduce the 
circuit scale of the apparatus, and it is also possible to selectively 
record or reproduce an HD signal and an SD signal. Also, it is possible to 
employ an SD monitor as an output monitor for an HD signal input. Further, 
since the SD monitor can be used as a monitor, it is possible to realize a 
camera-integrated type VTR which is reduced in size compared to 
conventional camera-integrated type VTRs. 
In the above-described embodiment, the HD mode, the SD-Low mode and the 
SD-High mode are prepared as the three recording modes. However, the kinds 
of modes are not limited to these modes, and it is also possible to use 
three modes such as HD, SD and ED modes. 
The manner of mode identification during reproduction and the sequence of 
control to be executed for the mode identification will be described below 
with reference to FIG. 35. 
Step P1: The current reproduction running mode of a VTR is confirmed. 
Step P2: A variable N is set to N=10 or N=20 according to which of the 
three modes is selected. 
Step P3: A sub-code is detected from a reproduced digital signal, and the 
mode used during recording is identified on the basis of the sub-code of 
the reproduced digital signal, and the required reproduction mode is 
determined. 
Step P4: The required number of tracks per unit time M and a data 
compression ratio CR are respectively set to M=10 or 20 and CR=5 or 10 in 
accordance with any one of the three modes which is indicated by 
reproduced ID data. 
Step P5: The target value of capstan speed control is set in accordance 
with the result of a comparison between the values of the variables N and 
M. 
The flow proceeds from Step P5 to any one of the succeeding three steps. 
If N&gt;M, it is determined that the current speed is greater than the speed 
used during recording, and the current speed is decreased. 
If N&lt;M, it is determined that the current speed is smaller than the speed 
used during recording, and the current speed is increased. 
If N=M, the current speed is kept. 
Step P6: A data expansion ratio is set to 1/CR and decoding is executed. 
The flow returns to Step P1 for confirming the current mode, and the 
above-described routine is repeated. 
To obtain a better understanding of the operation of the focusing control 
circuit 61 shown in FIG. 6, the relationship between system conversion 
(conversion between television systems) and TVAF (automatic focusing using 
a video signal) will be described below with reference to FIGS. 36 and 37. 
The amount of information carried by an HDTV signal is approximately five 
times that of information carried by an existing broadcasting (SD) system. 
Further, the HDTV signal contains more high-frequency spectrum components 
than the SD signal. 
FIG. 36 shows the level variations of the amount of high-frequency 
components contained in the respective signals conforming to the two 
broadcasting systems with respect to the movement of the focus of an image 
pickup optical system between its closest-distance position and its 
infinity position. Both curves A and B reach the respective peaks at an 
in-focus point. 
The curve A indicates the variation curve of the HDTV signal, while the 
curve B indicates the variation curve of the existing TV signal. The 
relationship between the heights at the in-focus point of the respective 
curves A and B is A.gtoreq.B. 
The relationship between the widths of in-focus areas "a" and "b" in which 
to restart an AF operation is a.ltoreq.b. A sharper curve provides a 
smaller in-focus area for which AF restarting computations must be 
executed more frequently. In consequence, the curve A can achieve a better 
focusing characteristic in terms of focusing accuracy. 
In other words, if HDTV video information which contains a larger amount of 
information is used, it is possible to achieve TVAF of higher performance. 
For this reason, in an image pickup system employing a down converter, 
video information which is not yet processed by the down converter is 
suitably used as information for the aforesaid TVAF. 
Incidentally, as shown in FIG. 37, signal frequency components differ 
between the existing NTSC and broadcasting systems as well. 
Accordingly, if optimum ones of the signal frequency components are 
selectively employed according to the kind of subject or photographic 
conditions (the illuminance of surroundings), it is possible to improve 
detection accuracy. 
As shown in the coordinate plane of FIG. 37 which is defined by three kinds 
of frequency axes, if it is assumed that the horizontal frequencies of the 
NTSC and video signals are the same, the NTSC system provides a 
picture which is made up of 60 fields/second with respect to the temporal 
frequency axis and 525 scanning lines with respect to the vertical 
frequency axis. Accordingly, the video signal components of the NTSC video 
signal are present in the frequency area defined by 60/2 and 525/2. 
The system provides a picture which is made up of 50 fields/second with 
respect to the temporal frequency axis and 625 scanning lines with respect 
to the vertical frequency axis. Accordingly, the video signal components 
of the video signal are present in the frequency area defined by 50/2 
and 625/2. 
By selectively utilizing the different characteristics in accordance with 
the kind of subject whose image is to be picked up and the kind of 
photographic mode, it is possible to further improve the performance of 
TVAF. 
The improvement of the performance of TVAF leads to not only an improvement 
in the diameter of a circle of least confusion at a final in-focus 
position but also an improvement in the stability of the process of 
finding an in-focus position (for example, an unstable behavior such as 
hunting or fluctuation can be reduced). 
As described above, a subject image is photoelectrically converted by the 
CCD built in the HDTV camera 60 and an HD signal having a high degree of 
definition and a large amount of information is outputted. 
An embodiment in which a concept called "scalability" is applied to the 
hierarchial structure of image information of a VTR to improve data 
handling will be described below with reference to FIGS. 38 to 49. 
A technique for performing coding or decoding and recording or reproduction 
of HD information in a structure in which an NTSC signal is included in 
the HD information will be described below with illustrative reference to 
a two-layer structure consisting of the HD information and the NTSC 
information. 
First, encoding of an NTSC signal is performed and the encoded sinal is 
transferred (or recorded). 
Then, a non-transmitted or unrecorded information portion is transferred 
(or recorded). 
An operation which is performed by recording means having the arrangement 
shown in FIG. 38 when an HD signal is inputted thereto will be described 
below. 
The input HD signal is down-converted into an SD signal by a down converter 
661, and the output of the down converter 661 is inputted to an SD-signal 
encoder 662. The encoded SD signal is divided into two channels by a 
recording channel divider 663, and the two outputs of the recording 
channel divider 663 are supplied to recording head amplifiers 671 and 673, 
respectively. Then, information recording tracks are formed on a magnetic 
recording medium 660 by magnetic recording heads 672 and 674. In the 
meantime, the output of the SD-signal encoder 662 is supplied to an 
SD-signal decoder 665 and, in an up converter 664, the output of the 
SD-signal decoder 665 is converted into an HD signal which contains an 
image distortion (error) occurring during encoding/decoding. If this 
degradation signal (recording SD information) is subtracted from the 
previous input signal, a difference signal for forming an HD signal can be 
obtained. Such a difference signal is formed by a subtractor 669, and the 
amount of data contained in the difference signal is reduced in a data 
compressor 666, and the output of the data compressor 666 is inputted into 
a data formatter 667 for causing the SD signal to conform to the recording 
standard of the HD signal. The output of the data formatter 667 is divided 
into two channels by a recording channel divider 668 similar to the 
aforesaid recording channel divider 663. The thus-obtained HD additional 
information is supplied to recording head amplifiers 675 and 677. Magnetic 
recording heads 676 and 678 sequentially record and form a pair of HD 
information recording tracks in an area adjacent to the pair of SD 
information recording tracks formed by the outputs of the divider 663 on 
the magnetic recording medium 660. 
The manner of the above-described recording operation is diagrammatically 
shown in FIG. 40. 
The SD information and the HD additional information, which are in the 
inclusive relationship shown by a symbolic block (left) representative of 
the amount of image information, are respectively recorded by two pairs of 
double azimuth (+/-) heads at the rate of two tracks at one time, and a 
total of four tracks constitute a basic unit. 
The tape transporting speed used during the above-described recording 
operation is selected to be two times the tape transporting speed used 
during SD recording (N=2). 
FIG. 39 is a schematic view showing the operation of an SD recording mode 
for recording only the SD information on a recording medium by one pair of 
double azimuth (+/-) heads at the rate of two tracks at one time. 
The tape transporting speed used during this recording operation is 
selected to be a standard speed (N=1). 
An example of the arrangement of reproducing means for reproducing 
arbitrary information from a magnetic tape on which SD information and HD 
additional information are recorded in the above-described manner will be 
described below, and the reproducing operation of the reproducing means 
will be described with reference to FIG. 41. 
Signals, which are respectively outputted from a pair of magnetic heads 702 
and 704 for tracing only a pair of SD information recording tracks on a 
magnetic tape 709 recorded in an HD recording mode, are respectively 
amplified by head amplifiers 701 and 703. The signals outputted from the 
head amplifiers 701 and 703 are integrated by a data combiner 693, and the 
output of the data combiner 693 is decoded from its recording data format 
into an SD signal, such as an NTSC signal, by an SD-signal decoder 692. 
The SD signal is converted into an HD-signal format by an up converter 
691. The processing of this SD-HD format conversion is the inverse of the 
processing performed by the above-described down converter. 
Signals, which are respectively outputted from a pair of magnetic heads 706 
and 708 for tracing only a pair of HD additional information recording 
tracks on the magnetic tape 709 recorded in the HD recording mode, are 
respectively amplified by head amplifiers 705 and 707. The signals 
outputted from the head amplifiers 705 and 707 are integrated by a data 
combiner 697, and the output of the data combiner 697 is decoded from its 
recording data format into a compressed HD additional signal by an 
HD-signal decoder 696. The compressed HD additional signal is converted 
into an HD additional signal by a data expander 695. 
The SD information and the HD additional information which have been 
converted into a common HD signal format in the above-described manner are 
added together by an adder 694, whereby the original HD signal is 
reconstructed. 
FIG. 42 schematically shows the manner of the above-described reproduction 
from the magnetic tape recorded in the HD recording mode. 
Both the period during which a pair of magnetic heads for tracing only a 
pair of HD additional information recording tracks on a magnetic tape 
recorded in the HD recording mode trace the magnetic tape and the period 
during which a pair of magnetic heads for tracing a pair of SD information 
recording tracks on the magnetic tape trace the magnetic tape are selected 
on the basis of the angle over which the magnetic tape is wrapped around a 
head drum. If each of the periods is selected to be 180 degrees, an HD 
additional data reproduction period and an SD data reproduction period 
appear alternately at intervals of one-half rotation of the head drum. 
During each of the data reproduction periods, the signals recorded on two 
tracks are reproduced by either of the pairs of double azimuth heads 
provided on the rotary drum. The signals recorded on a total of four 
tracks are reproduced as a basic unit. 
Accordingly, the signals recorded on four tracks which constitute the basic 
unit of the aforesaid information can be reproduced during one rotation of 
the head drum. The inclusive and combination relationships between the SD 
information and the HD additional information which are reproduced in the 
above-described manner are shown in the right-hand part of FIG. 42 by 
using symbolic blocks each representative of the amount of image 
information. 
Compatible reproduction which is most important in the present invention 
will be described below. 
The following description refers to a case where an SD recording apparatus 
having no recording function for the HD recording mode is used to perform 
reproduction from a magnetic tape recorded in the HD recording mode, as 
shown in FIG. 49. 
FIG. 44 shows the manner in which a pair of magnetic heads for tracing a 
pair of SD information recording tracks on a magnetic tape recorded in the 
SD recording mode traces the magnetic tape to reproduce an SD signal. Only 
one pair of double azimuth heads are provided on a head drum, and SD 
information alone is recorded on each track of the magnetic tape. In this 
case, each SD data reproduction period occurs only once during one 
rotation of the head drum. Since the tape transporting speed is the 
standard speed (N=1), the SD information recorded on each recording track 
is sequentially reproduced without skipping any of the recording tracks. 
FIG. 44 schematically shows the manner of the above-described reproducing 
operation. 
If recording-mode identification information, such as ID, is detected from 
a video area or a sub-code area by the detector 771 shown in FIG. 49 
during the SD recording mode reproducing operation, a compatible 
reproduction mode is selected. When a servo circuit 773 receives an 
instruction from the detector 771, the servo circuit 773 sets the current 
tape transporting speed to a double speed equal to the tape transporting 
speed for the HD reproduction mode. Incidentally, a motor 774 is provided 
for driving a capstan, and a frequency generator (FG) 775 is provided so 
that the servo circuit 773 can confirm the state of rotation of the 
capstan. 
The pair of double azimuth heads for SD signals, which are provided on the 
head drum, trace only pairs of SD information recording tracks on a 
magnetic tape recorded in the HD recording mode. However, since no 
magnetic heads for HD signals are provided, the magnetic tape is 
transported without tracing a pair of HD additional information tracks. 
Accordingly, an HD addition data track idle running period and an SD data 
reproduction period alternately appear at intervals of one-half rotation 
of the head drum. FIG. 43 schematically shows the manner of the 
above-described reproducing operation. 
Reproduction from only two tracks for SD signals out of four tracks which 
constitute one basic unit is performed by the pair of double azimuth (+/-) 
heads provided on the rotary drum, at intervals of one rotation period. 
The signal reproduced in the above-described manner is converted into an SD 
signal, such as an NTSC or signal, by the SD-signal decoder 772 shown 
in FIG. 49, and the SD signal is outputted from the SD-signal decoder 772. 
The manner of the above-described reproduction from the recorded tracks is 
shown in FIG. 45 in the form of a recording track pattern. 
The recording tracks shown in FIG. 45 constitute groups each consisting of 
four tracks indicated by characters "a" to "d" affixed to the respective 
numbers. 
The characters "a" and "b" indicate tracks for SD signals (represented by 
meshes), and the characters "c" and "d" indicate additional tracks for HD 
signals. 
In the compatible reproduction mode, reproduction from only the tracks "a" 
and "b" is performed, and no reproduction from the track "c" nor "d" is 
performed. 
FIG. 46 is a graphic representation showing a head relative speed Vhead 
determined by a tape transporting speed Vtape and a head drum rotational 
speed Vdrum, and the horizontal and vertical axes represent the tape 
transporting speed Vtape and the head drum rotational speed Vdrum, 
respectively. 
Since the head relative speed Vhead reaches 9,000 rotations during the SD 
mode, it is not practical to increase the rotational speed to a further 
extent for the purpose of coping with the HD mode. If the rotational speed 
is selected to be not less than 9,000 rotations, two kinds of trace angles 
are formed in the case of the respective standard and double speeds, as 
shown in FIG. 46. 
A line V1 indicates the case of reproduction of an SD mode recording, and a 
line V2 indicates the case of reproduction of an HD mode recording. In the 
case of the compatible reproduction mode according to the present 
embodiment, the tape transporting speed Vtape and the drum rotation speed 
Vhead are completely the same as those used in the HD reproduction mode, 
the head trace V2 is selected so that an SD track portion can be traced 
without any problem. Each of FIGS. 47 and 48 is a table showing whether 
each of the SD and HD reproduction modes can be used for magnetic tapes 
recorded in the respective SD and HD recording modes, and FIG. 47 shows 
the case of an SD signal reproducing apparatus, while FIG. 48 shows the 
case of an HD signal reproducing apparatus. 
As can be seen from FIGS. 47 and 48, not only the HD signal reproducing 
apparatus but also the SD signal reproducing apparatus can effect 
reproduction from any of the magnetic tapes recorded in the SD recording 
mode or the HD recording mode. 
It is to be noted that since reproduction from a magnetic tape recorded in 
the SD recording mode can be performed in the HD-signal format, "recording 
mode SD/reproduction mode HD" of FIG. 48 can also be regarded as 
"possible" although the image quality, such as resolution, is equivalent 
to SD quality. 
In the present embodiment, although the concept of a hierarchical coding 
system has been described with illustrative reference to pyramidal coding, 
the kind of coding system is not limited to the pyramidal coding. For 
example, another hierarchical coding technique, such as sub-band coding, 
can of course be used without departing from the scope and spirit of the 
present invention. 
Incidentally, the head relative speed Vhead is not limited to 9,000 
rotations, and, for example, 4,500 rotations may be selected. It is also 
possible to adopt an arrangement which switches the head relative speed 
Vhead as well as the characteristics of its control system on the basis of 
a decision as to whether the HD mode or the SD mode is selected. 
According to the embodiment utilizing the above-described scalability, it 
is possible to achieve a remarkable improvement in the characteristic of 
compatible reproduction from a recorded medium, which cannot be attained 
by conventional image recording systems because of their different coding 
systems. 
Also, it is possible to effect reproduction from a recording medium 
recorded in any recording mode, by means of not only higher-order 
equipment but also lower-order equipment. 
Furthermore, since a lower-order system needs only to have a servo 
mechanism for effecting switching between media driving speeds, users can 
easily introduce lower-order systems without making large prior 
investments.