Control of an image display based on a permission signal

The display of an image in a mode which is against the intentions of the producer is made possible. An additional information decoder decodes timing information and edge.sub.-- crop.sub.-- flag from additional information codes supplied from a demultiplexer, and outputs them to a controller. The flag edge.sub.-- crop.sub.-- flag indicates whether or not a display in the edge cropped mode is permitted by the producer of the image. The controller turns on a horizontal filter and turns off a vertical filter when this flag indicates the permission in the edge cropped mode or when the edge cropped mode is instructed from an external control signal, and causes an image in the edge cropped mode to be displayed on a monitor having an aspect ratio of 4:3. When the edge cropped mode is prohibited, the horizontal filter is turned off, and the vertical filter is turned on, causing the image to be displayed in the letter box mode.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a coding apparatus and method, a decoding 
apparatus and method, and a record medium. More particularly, the present 
invention relates to a coding apparatus and method, a decoding apparatus 
and method, and a record medium, in which an image can be prevented from 
being displayed in a display state which is against the intentions of the 
producer. 
2. Description of the Related Art 
FIG. 10 shows an example of the construction of a conventional coding 
apparatus for coding image signals. In this example, an image generated in 
an image generating apparatus 1 is supplied to a video coder 11 of a 
coding apparatus 2 in accordance with a predetermined sequence. The image 
generating apparatus 1 further generates a frame number and outputs it to 
the video coder 11. Furthermore, the image generating apparatus 1 time 
information for the generated image and supplies it to a multiplexer 12 of 
the coding apparatus 2. The video coder 11 codes the input image and 
outputs the coded data (video codes) to the multiplexer 12. The 
multiplexer 12 multiplexes the video codes input from the video coder 11 
onto the time information input from the image generating apparatus 1, and 
outputs it as a bitstream. 
Next, the operation of the coding apparatus will be described. The video 
coder 11 codes the image input from the image generating apparatus 1 
together with the frame number by an MPEG (Moving Picture Experts Group) 
method. Then, the video coder 11 outputs the video codes obtained as a 
result of the coding to the multiplexer 12. The multiplexer 12 multiplexes 
the time information output from the image generating apparatus 1 onto the 
video codes output from the video coder 11, and outputs it as a bitstream. 
FIG. 11 shows an example of the construction of a decoding apparatus for 
decoding a bitstream which is coded by the coding apparatus and which is 
output therefrom in this way. In this example, a bitstream is input to a 
demultiplexer 31 of a decoding apparatus 21. The demultiplexer 31 
demultiplexes (isolates) video codes from the input bitstream. The video 
codes output from the demultiplexer 31 are input to a video decoder 32. 
The video decoder 32 decodes the input video codes and outputs an image to 
a horizontal filter 33. The horizontal filter 33 performs an operation of 
enlarging or reducing the horizontal length of the input image signals, 
and outputs it to a vertical filter 34. The vertical filter 34 performs an 
operation of enlarging or reducing the vertical length of the input 
signals, and outputs it to a monitor 22 and a monitor 23. 
The time information isolated by the demultiplexer 31, and the frame number 
which is decoded and output by the video decoder 32 are not particularly 
used in this example. Therefore, a description thereof is omitted. 
A control signal is input to a controller 35 from an apparatus (not shown). 
The controller 35, in response to this control signal, controls the 
horizontal filter 33 and the vertical filter 34. 
In the image decoding apparatus shown in FIG. 11, an encoder for converting 
the image signals output from the video decoder 32 into signals of an NTSC 
(National Television System Committee) system is omitted. 
Next, the operation of the image decoding apparatus will be described 
below. The demultiplexer 31 isolates video codes from the input bitstream 
and outputs them to the video decoder 32. The video decoder 32 isolates 
image signals from the input video codes and outputs them to the 
horizontal filter 33. 
The image signals obtained as a result of decoding by the video decoder 32, 
as shown in FIG. 12(A), are made to be an image for the monitor 23 having 
an aspect ratio of 16:9. That is, for this image, an image to be displayed 
on the monitor 23 having an aspect ratio of 16:9 is made to be an image 
having an aspect ratio of 4:3 by compressing (thereby forming into an 
oblong image) the length of the image in a horizontal direction, thus 
forming an oblong image having an aspect ratio of 4:3. 
In a case in which the user sees this decoded image on the monitor 23 
having an aspect ratio of 16:9, the user inputs an external control signal 
to the controller 35, causing the horizontal filter 33 to be turned off, 
as well as the vertical filter 34. As a result, the oblong image, shown in 
FIG. 12(A), which is output from the video decoder 32, is output unchanged 
from the horizontal filter 33 which is turned off, as shown in FIG. 12(C). 
At this time, since the vertical filter 34 is also turned off, the 
vertical filter 34, as shown in FIG. 12(E), outputs this image as is on 
the monitor 23. Since the monitor 23 has an aspect ratio of 16:9, an image 
(an oblong image) whose length is compressed in the horizontal direction 
is expanded in the horizontal direction. As a result, a normal image (an 
image whose ratio of length to width is the same and which has no lost 
portions), shown in FIG. 12(I), is displayed on the monitor 23. As a 
result, it is possible to enjoy a dynamic image having a wide screen. 
Incidentally, in a case in which the user does not have a monitor 23 having 
an aspect ratio of 16:9, but has only a monitor 22 having an aspect ratio 
of 4:3, the user is able to select and instruct any one of the modes such 
as a squeezed mode, a letter box mode, and an edge cropped mode by 
inputting an external control signal to the controller 35. 
The controller 35, when the squeezed mode is instructed, turns off both the 
horizontal filter 33 and the vertical filter 34. As a result, when the 
image shown in FIG. 12(E) is input to the vertical filter 34, the vertical 
filter 34 outputs the image as is onto the monitor 22 without performing 
any special process. As a result, an oblong image shown in FIG. 12(H) is 
displayed as is on the monitor 22 having an aspect ratio of 4:3. 
On the other hand, in a case in which a letter box mode is instructed, the 
controller 35 turns off the horizontal filter 33 and turns on the vertical 
filter 34. When an oblong image shown in FIG. 12(C) is input via the 
horizontal filter 33, the vertical filter 34 performs an operation of 
compressing the length of the image in the vertical direction. As a result 
of this operation, an image is obtained whose ratio of length to width is 
the same. However, since regions where there is substantially no image, 
are formed in the upper and lower portions of the screen having an aspect 
ratio of 4:3, a black-level image is inserted into those regions, and thus 
an image such as that shown in FIG. 12(D) is formed. When this image is 
output from the vertical filter 34 and is displayed on a monitor 22 having 
an aspect ratio of 4:3, as shown in FIG. 12(G), an image in which 
no-signal regions are formed in the upper and lower portions of the screen 
is displayed as a normal image whose ratio of length to width is 1:1. 
Further, when an edge cropped mode is instructed, the controller 35 turns 
on the horizontal filter 33 and turns off the vertical filter 34. When an 
oblong image shown in FIG. 12(A) is input from the video decoder 32, the 
horizontal filter 33 removes the image near the left and right end 
portions of this image. As a result, an image shown in FIG. 12(B) is 
obtained. When this image is displayed on the monitor 22 having an aspect 
ratio of 4:3 via the vertical filter 34, an image such as that shown in 
FIG. 12(F) is displayed on the monitor 22. This image is an image whose 
ratio of length to width is 1:1; however, a part of the image near the 
left and right end portions of this image is lost. 
As described above, the edge cropped mode from among the above-described 
modes is a mode in which a part of an image is cut and displayed in order 
to adjust it to a monitor having an aspect ratio of 4:3. For this reason, 
since in this mode an image different from the intentions of the producer 
of the image is displayed, there is a risk in that a problem concerning 
copyright might occur. 
In order to avoid this problem, by making the producer of the image specify 
by a portion of the image to be cut in the edge cropped mode, permission 
for coding the image may thus be obtained. However, for example, when a 
title or a person's name is displayed on the entire screen, it is often 
not possible to cut any portion. In such a case, since a part of the title 
or the person's name is cut when a display is made in the above-described 
edge cropped mode, as a result, a situation may arise in which permission 
for coding the image (e.g., a movie) and recording it on a record 
(recording, recordable or recorded) medium, and for transmitting the image 
cannot be obtained from the producer of the image. 
SUMMARY OF THE INVENTION 
The present invention has been achieved in view of the above-described 
situation. It is an object of the present invention to prevent an image 
from being displayed in a display state when is against the intentions of 
the producer. 
The coding method according to one aspect of the invention includes the 
steps of: coding image signals; and coding additional information 
including a permission signal indicating whether or not a display of an 
image in a predetermined display state should be permitted. 
In the record medium, image signals and a permission signal indicating 
whether or not a display of an image in a predetermined display state 
should be permitted, are coded and multiplexed, and recorded. 
The decoding apparatus includes isolation means for isolating the image 
signals and a permission signal from the input signals; and control means 
for controlling the display state of the isolated image signals in 
response to the isolated permission signal. 
The decoding method includes the steps of isolating the image signals and a 
permission signal from the input signals; and controlling the display 
state of the isolated image signals in response to the isolated permission 
signal. 
The above and further objects, aspects and novel features of the invention 
will become more apparent from the following detailed description when 
read in connection with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred embodiments of the present invention will be explained below. 
FIG. 1 is a block diagram illustrating an example of the construction of a 
coding apparatus of the present invention employing a coding method in 
accordance with the present invention. Components in FIG. 1 which 
correspond to those in FIG. 10 are given the same reference numerals. As 
shown in FIG. 1, the basic construction of this coding apparatus is the 
same as that shown in FIG. 10 except that the coding apparatus 2 of FIG. 1 
is provided with an additional information coder 41. This additional 
information coder 41, when additional information including timing 
information and a flag Edge.sub.-- crop.sub.-- flag are input from an 
apparatus (not shown), codes this additional information, and outputs it 
as additional information codes to the multiplexer 12. 
The multiplexer 12 multiplexes the video codes input from the video coder 
11 and the time information input from the image generating apparatus 1 
onto the additional information codes input from the additional 
information coder 41, and transmits the multiplexed codes as a bitstream 
to a transmission line (not shown). 
This bitstream is supplied to a recording apparatus 43, and is recorded on 
a record (recording, recordable or recorded) medium 42, such as a digital 
video disk or a video tape. The other components are the same as those 
shown in FIG. 10. 
Edge.sub.-- crop.sub.-- flag is a flag for indicating whether or not a 
display of an image in an edge cropped mode should be permitted. The 
timing information indicates the period (the range of the image) during 
which the flag is effective. Both of the Edge.sub.-- crop.sub.-- flag and 
the timing information are set based on the intentions of the producer 
(the owner of the copyright). 
Concerning timing information, information which specifies an image in an 
image sequence, such as the frame number of the image or the display time, 
may be used. For example, the frame number of the image is expressed as a 
temporal reference in the MPEG video layer. The display time is expressed 
in the form of a presentation time stamp (PTS) or the like in the MPEG 
system layer. Therefore, it is possible to specify the range in which the 
display in the edge cropped mode is permitted by using such information. 
The above-described flag and timing information are coded as additional 
information codes by the additional information coder 41, and are 
multiplexed together with the video codes output from the video coder 11 
at a proper position by the multiplexer 12, and thus a bitstream is 
formed. 
If, for example, the bitstream is an MPEG program stream, assuming that the 
additional information codes are a part of a PSM (Program Stream Map) in 
the system layer, the additional information coder 41 codes the additional 
information. Then, the PSM output from the additional information coder 41 
is multiplexed in the more forward portion in relation to time than the 
position of the video codes of the image specified by the timing 
information by means of the multiplexer 12. 
The syntax of the PSM in the MPEG2 will be shown below. 
______________________________________ 
Syntax or Program Stream Map! 
program.sub.-- stream.sub.-- map() { 
packet.sub.-- start.sub.-- code.sub.-- prefix 
24 bslbf 
map.sub.-- stream.sub.-- id 
8 uimsbf 
program.sub.-- stream.sub.-- map.sub.-- length 
16 uimsbf 
current.sub.-- next.sub.-- indicator 
1 bslbf 
reserved 2 bslbf 
program.sub.-- stream.sub.-- map.sub.-- version 
5 uimsbf 
reserved 7 bslbf 
marker.sub.-- bit 1 bslbf 
program.sub.-- stream.sub.-- info.sub.-- length 
16 uimsbf 
for (i=0;i&lt;N;i++) { 
descriptor () 
elementary.sub.-- stream.sub.-- map.sub.-- length 
16 uimsbf 
for (i=0;i&lt;N1;i++) { 
stream.sub.-- type 
8 uimsbf 
elementary.sub.-- stream.sub.-- id 
8 uimsbf 
elementary.sub.-- stream.sub.-- info.sub.-- length 
16 uimsbf 
for (i=0;i&lt;N12;i++) { 
descriptor () 
} 
} 
CRC.sub.-- 32 32 rpchof 
} 
______________________________________ 
bs1bf(bit string left bit first) means that data of bit stream is arranged 
with the bit of the left side being at the beginning. uimsbf(unsigned 
integer most significant bit first) means that data of an unsigned integer 
is arranged with the bit of the MSB side being at the beginning. 
rpchof(remainder polynomial coefficients highest order first) means that 
coefficients of a remainder polynomial are arranged in the ascending order 
of its degree. 
An example of writing Edge.sub.-- crop.sub.-- flag in the above-described 
descriptor() of the PSM will be shown. As a private descriptor(), 
Edge.sub.-- crop.sub.-- descriptor() is defined as shown below. 
______________________________________ 
Syntax of Edge.sub.-- crop.sub.-- descriptor! 
Edge.sub.-- crop.sub.-- descriptor() { 
descriptor.sub.-- tag 
8 uimsbf 
descriptor.sub.-- length 
8 uimsbf 
Edge.sub.-- crop.sub.-- flag 
1 uimsbf 
reserved 3 bslbf 
Start.sub.-- PTS 32..30! 
3 bslbf 
marker.sub.-- bit 
1 bslbf 
Start.sub.-- PTS 29..15! 
15 bslbf 
marker.sub.-- bit 
1 bslbf 
Start.sub.-- PTS 14..0! 
15 bslbf 
marker.sub.-- bit 
1 bslbf 
reserved 4 bslbf 
End.sub.-- PTS 32..30! 
3 bslbf 
marker.sub.-- bit 
1 bslbf 
End.sub.-- PTS 29..15! 
15 bslbf 
marker.sub.-- bit 
1 bslbf 
End.sub.-- PTS 14..0! 
15 bslbf 
marker.sub.-- bit 
1 bslbf 
______________________________________ 
In the above edge.sub.-- crop.sub.-- descriptor(), descriptor.sub.-- tag 
indicates the type of descriptor. After that, edge.sub.-- crop.sub.-- flag 
is written. The timing information indicating the effective period of this 
edge.sub.-- crop.sub.-- flag is expressed by, for example, Presentation 
Time Stamp (PTS). That is, as Syntax, Start.sub.-- PTS indicating the 
start of the effective period and End.sub.-- PTS indicating the end are 
defined. 
In a case in which PSM is placed for each of a predetermined range (e.g., 
every several GOPs (Groups of Pictures)) of the bitstream, if it is 
defined that edge.sub.-- crop.sub.-- flag of Edge.sub.-- crop.sub.-- 
descriptor() of a certain PSM is effective in that range, the 
above-described timing information is not required. Thus, Edge.sub.-- 
crop.sub.-- descriptor2() having Syntax shown below can be defined. Or, 
even if edge.sub.-- crop.sub.-- flag of edge.sub.-- crop.sub.-- 
descriptor() of a certain PSM is effective until edge.sub.-- crop.sub.-- 
descriptor() appears in the PSM which follows the above PSM, the 
above-described timing information can be omitted and can be defined by 
the Edge.sub.-- crop.sub.-- descriptor2() shown below. 
______________________________________ 
Syntax of Edge.sub.-- crop.sub.-- descriptor2! 
Edge.sub.-- crop.sub.-- descriptor2() { 
descriptor.sub.-- tag 
8 uimsbf 
descriptor.sub.-- length 
8 uimsbf 
Edge.sub.-- crop.sub.-- flag 
1 uimsbf 
reserved 7 bslbf 
______________________________________ 
The bitstream containing the above-described additional information codes 
is recorded on a record medium 42 (a digital video disk or a digital video 
tape), or transmitted on the transmission line. 
The bitstream which is reproduced from the record medium 42 or which is 
transmitted through the transmission line is decoded by a decoding 
apparatus shown in FIG. 2. In this embodiment, the demultiplexer 31 of the 
decoding apparatus 21 isolates additional information codes from the input 
bitstream and outputs the additional information codes to an additional 
information decoder 51. The additional information decoder 51 decodes the 
input additional information codes, isolates them into timing information 
and edge.sub.-- crop.sub.-- flag, and outputs them to the controller 35. 
Input to this controller 35 is a frame number decoded by the video decoder 
32. The controller 35 discriminates the start point and the end point of 
the period defined in the timing information from this timing information 
or the frame number. The other components are the same as those in FIG. 
11. 
Also in this embodiment of FIG. 2, an encoder for converting decoded image 
signals into signals of an NTSC system is omitted. Further, although 
usually, in addition to image signals, voice and data codes are 
transmitted and isolated, this is omitted in this embodiment. 
Next, the operation of this embodiment will be described. Initially, the 
bitstream is isolated into video codes and additional information codes by 
the demultiplexer 31. These video codes are decoded by the video decoder 
32, and image signals and a frame number can be obtained. The image 
signals are supplied to the horizontal filter 33, and the frame number is 
supplied to the controller 35. Further, the additional information codes 
are decoded as the above-described edge.sub.-- crop.sub.-- flag and timing 
information by the additional information decoder 51 and sent to the 
controller 35. 
The controller 35 controls on/off of the horizontal filter 33 and the 
vertical filter 34 on the basis of the input information as shown in the 
flowcharts of FIGS. 3 and 4. 
In the first step S1, a check is made to determine if the flag edge.sub.-- 
crop.sub.-- flag is 1, namely, an edge cropped mode is permitted. When the 
edge cropped mode is permitted (when edge.sub.-- crop.sub.-- flag=1), the 
process proceeds to step S2 where a check is made to determine if a 
control signal has been input from outside. When a control signal has not 
been input, the process returns to step S1, and the processes of step 1 
and et seq. are repeatedly performed. That is, in this case, 
substantially, no special process is performed (the decoded image is 
displayed as is). 
When it is determined in step S2 that a control signal has been input, 
which mode of the squeezed mode, the letter box mode, and the edge cropped 
mode this control signal requests is determined in steps S3 to S5. 
When it is determined in step S3 that the squeezed mode is requested, the 
process proceeds to step S6 where the controller 35 turns off the 
horizontal filter 33 and the vertical filter 34. That is, the squeezed 
mode is set. When it is determined in step S4 that the letter box mode is 
requested, the process proceeds to step S7 where the controller 35 turns 
off the horizontal filter 33 and turns on the vertical filter 34. That is, 
as a result, the letter box mode is set as requested. Further, when it is 
determined in step S5 that the edge cropped mode is requested, the process 
proceeds to step S8 where the controller 35 turns on the horizontal filter 
33 and turns off the vertical filter 34. That is, as a result, the edge 
cropped mode is set as requested. 
As described above, in these cases, the squeezed mode, the letter box mode, 
or the edge cropped mode is set as requested in accordance with an 
external control signal, and the above-described image shown in FIGS. 
12(H), 12(G) and 12(F) is displayed. 
When it is determined in step S1 that the flag edge.sub.-- crop.sub.-- flag 
is not 1 (is 0) a display in the edge cropped mode is not permitted 
(prohibited)!, the process proceeds to step S9 where a check is made to 
determine if the current display mode is an edge cropped mode. When the 
display mode is not an edge cropped mode, the flag edge.sub.-- crop.sub.-- 
flag has substantially no meaning, and the process returns to step S1 
without performing any special process, and the process of step 1 and et 
seq. is repeatedly performed. 
When it is determined in step S9 that the current display mode is an edge 
cropped mode, the process proceeds to step S10 where the horizontal filter 
33 which has been turned on in the edge cropped mode is turned off. That 
is, in this case, since the display in the edge cropped mode is 
prohibited, the display in the edge cropped mode is made to be prohibited. 
Next, the process proceeds to step S11 where the vertical filter 34 which 
has been turned off in the edge cropped mode is turned on. That is, the 
processes of step S10 and step S11 produce the same result as when the 
letter box mode is set. Therefore, when the edge cropped mode is 
prohibited in the predetermined image in a state in which the edge cropped 
mode is set, and the image shown in FIG. 12(F) is seen, the displayed 
image is automatically changed to the display image of the letter box 
mode, shown in FIG. 12(G). 
Next, the process proceeds to step S12 where a check is made to determine 
if a control signal has been input from outside. If a control signal has 
not been input, the process returns to step S1, and the processes of step 
1 and et seq. are repeatedly performed. When a control signal has been 
input, the process proceeds from step 12 to steps S13 to S15 where which 
mode of the squeezed mode, the letter box mode, and the edge cropped mode 
has been requested is determined. 
When it is determined in step S13 that the squeezed mode is requested, the 
process proceeds to step S16 where the controller 35 turns off both the 
horizontal filter 33 and the vertical filter 34. That is, as a result, the 
squeezed mode is set, and the image shown in FIG. 12(H) is displayed. 
When, on the other hand, it is determined in step S14 that the letter box 
mode has been requested, the process proceeds to step S17 where the 
horizontal filter 33 is turned off and the vertical filter 34 is turned 
on. That is, as a result, the letter box mode is set, and the image shown 
in FIG. 12(G) is displayed. 
In comparison with this, when it is determined in step S15 that the edge 
cropped mode has been requested, the process proceeds to step S18 where 
the horizontal filter 33 is turned off, and the vertical filter 34 is 
turned on. That is, in this case, the request is an edge cropped mode. 
However, in this case, since the setting of the edge cropped mode is 
prohibited, substantially the letter box mode is set. As a result, the 
image of the letter box mode shown in FIG. 12(G) is displayed. 
FIG. 5 shows another example of the construction of the decoding apparatus. 
In this embodiment, the vertical filter 34 is omitted, and only the 
horizontal filter 33 is provided. The other components are the same as 
those shown in FIG. 2. 
In this embodiment, as shown in FIG. 6, as the display mode, only the 
squeezed mode and the edge cropped mode are provided. 
The controller 35 performs the processes shown in the flowchart of FIG. 7. 
Initially, in step S31, a check is made to determine if the flag 
edge.sub.-- crop.sub.-- flag is 1 (whether or not the edge cropped mode 
has been permitted). When this flag is 1 (when the edge cropped mode has 
been permitted), the process proceeds to step S32 where a check is made to 
determine if a control signal has been input from outside. When a control 
signal has not been input, the process returns to step S31 without 
particularly performing any process, and the processes of step S31 and et 
seq. are repeatedly performed. 
When a control signal has been input from outside, the process proceeds to 
steps S33 and S34 where a check is made to determine if the request by the 
control signal is the squeezed mode or the edge cropped mode. 
When it is determined in step S33 that the squeezed mode has been 
requested, the process proceeds to step S35 where the controller 35 turns 
off the horizontal filter 33. As a result, the oblong image shown in FIG. 
6(A) output from the video decoder 32 is output as is as shown in FIG. 
6(B) from the horizontal filter 33, and is displayed as an image of the 
squeezed mode (as an oblong image) on the monitor 22 having an aspect 
ratio of 4:3, as shown in FIG. 6(E). In a case in which the monitor 23 
having an aspect ratio of 16:9 is connected to this decoding apparatus 21, 
as shown in FIG. 6(D), a normal image whose ratio of length to width is 
the same is displayed. 
When, on the other hand, it is determined in step S34 that the edge cropped 
mode has been requested, the process proceeds to step S36 where the 
horizontal filter 33 is turned on. Therefore, the horizontal filter 33, 
when the oblong image shown in FIG. 6(A) is input, generates an image 
whose ratio of length to width is 1:1 by removing a part of the image on 
the left and right as shown in FIG. 6(C), and outputs the image onto the 
monitor 22 having an aspect ratio of 4:3. As a result, an image of the 
edge cropped mode, shown in FIG. 6(F), is displayed on the monitor 22. 
On the other hand, when it is determined in step S31 that the flag 
edge.sub.-- crop.sub.-- flag is not 1 (is 0) (when the edge cropped mode 
is prohibited), the process proceeds to step S35 where the controller 35 
turns off the horizontal filter 33. That is, in this case, the squeezed 
mode is forcibly set. As a result, the oblong image shown in FIG. 6(E) is 
displayed as is on the monitor 22. However, when the monitor 23 having an 
aspect ratio of 16:9 is connected to the decoding apparatus 21, a normal 
image shown in FIG. 6(D) is displayed. 
As described above, in this embodiment, when the edge cropped mode is 
prohibited, the limitation by the control signal is made substantially to 
be nullified. 
FIG. 8 shows another example of the construction of the coding apparatus. 
In this embodiment, an edge.sub.-- crop.sub.-- flag table 61 is provided 
in the coding apparatus 2, and a frame number is input from the image 
generating apparatus 1. The edge.sub.-- crop.sub.-- flag table 61 outputs 
a flag edge.sub.-- crop.sub.-- flag for each input frame number, and 
outputs it to the video coder 11. The video coder 11 codes (multiplexes) 
this flag edge.sub.-- crop.sub.-- flag together with the image and the 
frame number supplied from the image generating apparatus 1, and outputs 
it as video codes. 
Therefore, in this embodiment of FIG. 8, the additional information coder 
41 and the multiplexer 12, shown in FIG. 1, are omitted. 
That is, in this embodiment, the video coder 11 codes the image and the 
frame number output from the image generating apparatus 1, as well as 
codes the flag edge.sub.-- crop.sub.-- flag which is input for each frame 
number from the edge.sub.-- crop.sub.-- flag table 61, multiplexes the 
flag onto the video codes, and outputs it. 
For example, in the MPEG2, Video Syntax is defined as shown below. 
______________________________________ 
video.sub.-- sequence() { 
next.sub.-- start.sub.-- code() 
sequence.sub.-- header() 
if (nextbits() == extension.sub.-- start.sub.-- code) { 
sequence.sub.-- extension() 
do { 
extension.sub.-- and.sub.-- user.sub.-- data(0) 
do { 
if ( nextbits() == group.sub.-- start.sub.-- code) { 
group.sub.-- of.sub.-- pictures.sub.-- header() 
extension.sub.-- and.sub.-- user.sub.-- data(1) 
} 
pictures.sub.-- header() 
pictures.sub.-- coding.sub.-- extension() 
extensions.sub.-- coding.sub.-- and.sub.-- user.sub.-- 
data(2) 
pictures.sub.-- data() 
} while ((nextbits() == pictures.sub.-- start.sub.-- code) 
.parallel. 
(nextbits() == group.sub.-- start.sub.-- code)) 
if (nextbits() |= sequence.sub.-- end.sub.-- code ) { 
sequence.sub.-- header() 
sequence.sub.-- extension() 
} 
} while (nextbits() |= sequence.sub.-- end.sub.-- code ) 
} else { 
/* ISO/IEC 11172-2 : MPEG1 */ 
sequence.sub.-- end.sub.-- code 
} 
______________________________________ 
In the above-described Syntax, extensions.sub.-- and.sub.-- user.sub.-- 
data(2) is provided after the pictures.sub.-- header(), for example, 
edge.sub.-- crop.sub.-- data() is defined as shown below in accordance 
with the Syntax of the extensions.sub.-- and.sub.-- user.sub.-- data, and 
edge.sub.-- crop.sub.-- flag is coded within the edge.sub.-- crop.sub.-- 
data(). 
______________________________________ 
Syntax of User.sub.-- data defined in the MPEG! 
user.sub.-- data() { 
user.sub.-- data.sub.-- start.sub.-- code 
while(nextbits() |= "0000 0000 0000 0000 0000 0001") { 
user.sub.-- data (8bit) 
next.sub.-- start.sub.-- code() 
} 
______________________________________ 
Edge.sub.-- Crop.sub.-- data() is defined as shown below in accordance with 
the above-described Syntax. 
______________________________________ 
Edge.sub.-- Crop.sub.-- data() { 
user.sub.-- data.sub.-- start.sub.-- code 
while(nextbits() |= "0000 0000 0000 0000 0000 0001") { 
Edge.sub.-- Crop.sub.-- flag 
(1bit) 
reserved (7bit) 
next.sub.-- start.sub.-- code() 
} 
______________________________________ 
Therefore, in the coding apparatus of FIG. 8, the video coder 11 receives 
Edge.sub.-- crop.sub.-- flag and codes this as a part of User data of each 
image frame as described above. 
FIG. 9 shows an example of the construction of the decoding apparatus for 
decoding the image signals coded by the coding apparatus of FIG. 8. The 
input video codes (the bitstream) are decoded by the video decoder 32. At 
this time, a decoded image is obtained, and Edge.sub.-- Crop.sub.-- flag 
(additional information) is decoded as a part of extensions.sub.-- 
and.sub.-- user.sub.-- data(2) which follows each picture.sub.-- header. 
This Edge.sub.-- Crop.sub.-- flag is sent to the controller 35 at the 
timing in synchronization with the corresponding decoded image. The 
controller 35 controls the horizontal filter 33 and the vertical filter 34 
in the same way as in the embodiment of FIG. 2 in accordance with the 
supplied Edge.sub.-- Crop.sub.-- flag and the external control signal. 
In this embodiment, since edge.sub.-- crop.sub.-- flag (additional 
information) is added for each frame, it is not necessary to code and 
multiplex the timing information indicating the effective range of the 
flag, and since the signal is closed only in the Picture Layer, the 
construction becomes simple. However, conversely, it is necessary to 
explicitly code Edge.sub.-- crop.sub.-- flag for all the image frames. 
Further, since Edge.sub.-- crop.sub.-- flag is present in the Picture 
Layer, it is necessary to decode the video codes in order to know the 
value of the flag. 
The present invention is not limited to these embodiments. For example, 
Edge.sub.-- crop.sub.-- flag and this image in the embodiment of FIGS. 1 
and 2 are not necessarily required to be coded as a part of PSM of the 
system layer. For example, they may be coded as a private packet defined 
in the MPEG system layer. 
Further, for example, the additional information in which Edge.sub.-- 
crop.sub.-- flag is coded in the embodiment in FIGS. 8 and 9 may be coded 
as a part of extension.sub.-- and.sub.-- user.sub.-- data(0) which follows 
sequence.sub.-- header by collecting for each sequence formed of a 
collection of group of pictures, or may be coded collectively for each 
group of pictures. In such a case, the edge crop is prohibited in units of 
sequence layer or GOP layer. 
Although this embodiment describes only the edge cropped mode, the same 
applies to the squeezed mode as well. That is, since the image is 
displayed to be oblong in the squeezed mode, there are some owners of 
copyrights who think that originality is deteriorated. In this connection, 
it may be possible to provide a squeeze.sub.-- flag indicating whether or 
not a display in the squeezed mode should be permitted. 
That is, 1 bit from among 7 bits reserved for user data is assigned to such 
squeeze.sub.-- flag, and the squeezed mode is forcibly changed to the 
letter box mode. Further, it is also possible to make edge.sub.-- 
crop.sub.-- flag serve also as a flag for prohibiting the squeezed mode. 
In such a case, regardless of the current display mode, both of the edge 
cropped mode and the squeezed mode are prohibited, and a display is 
forcibly made in the letter box mode. 
According to one coding method, since image signals are coded, and 
additional information including a permission signal indicating whether or 
not a display of an image in a predetermined display state should be 
permitted is coded, it becomes possible to prevent the coding of an image 
which might be displayed in a display state which is against the 
intentions of the producer. 
According to the record medium, since image signals, and a permission 
signal indicating whether or not a display of an image in a predetermined 
display state should be permitted are coded and multiplexed, and recorded, 
it becomes possible to prevent the recording of an image which might be 
displayed in a display state which is against the intentions of the 
producer. 
According to the decoding apparatus and the display mode, since image 
signals and a permission signal are isolated from the input signals, and 
the display state of the isolated image signals is controlled in response 
to the isolated permission signal, it becomes possible to prevent the 
display of an image which might be displayed in a display state which is 
against the intentions of the producer. 
Many different embodiments of the present invention may be constructed 
without departing from the spirit and scope of the present invention. It 
should be understood that the present invention is not limited to the 
specific embodiments described in this specification. To the contrary, the 
present invention is intended to cover various modifications and 
equivalent arrangements included within the spirit and scope of the 
invention as hereafter claimed. The scope of the following claims is to be 
accorded the broadest interpretation so as to encompass all such 
modifications, equivalent structures and functions.