Coding method for notion-image data, decoding method, terminal equipment executing these, and two-way interactive system

Abstract

This invention relates to a coding method for motion-image data and others effective in a special interactive environment for transmitting motion-image data with information concentrated on only a partial region of a display image as in a two-way interactive system implementing real-time two-way interaction. The coding method involves dividing an image frame forming motion-image data into a plurality of rectangular regions, and grouping each of these rectangular regions into a preset ROI and a non-ROI. These rectangular regions are sequentially compressed so that a code length of a rectangular region grouped into the ROI is larger than a code length of a rectangular region grouped into the non-ROI, thereby generating coded data of each image frame.

1 . A coding method for motion-image data in which each of image frames constituting motion-image data is sequentially compressed along a time axis, the method comprising the steps of: 
 dividing an image frame to be coded among the image frames constituting the motion-image data, into a plurality of sub-regions;    grouping each of the plurality of sub-regions into either of a region of interest set in the image frame and a region of no interest different from the region of interest; and    compressing each of the plurality of sub-regions so that a code length of a sub-region grouped into the region of interest out of the plurality of sub-regions is larger than a code length of a sub-region grouped into the region of no interest, thereby generating coded data of each image frame.    
   
   
       2 . A coding method for motion-image data according to  claim 1 , wherein a sub-region in which a motion of an image is detected, out of the plurality of sub-regions, is grouped into the region of interest.  
   
   
       3 . A coding method for motion-image data according to  claim 1 , wherein a plurality of sub-regions are grouped into the region of interest and the sub-regions grouped into the region of interest are compressed so that code lengths of the respective sub-regions are different from each other.  
   
   
       4 . A coding method for motion-image data according to  claim 1 , wherein in a process of coding the sub-region grouped into the region of no interest out of the plurality of sub-regions, the code length of the sub-region is 0 during a certain period of time.  
   
   
       5 . A coding method for motion-image data according to  claim 1 , wherein coded data corresponding to the sub-region grouped into the region of interest out of the plurality of sub-regions is further encrypted.  
   
   
       6 . A coding method for motion-image data according to  claim 1 , wherein the image frames constituting the motion-image data are divided so that the region of interest constitute one sub-region.  
   
   
       7 . A coding method for motion-image data according to  claim 6 , wherein a division size of the sub-regions is dynamically changed corresponding to a size variation of the region of interest.  
   
   
       8 . A coding method for motion-image data according to  claim 1 , wherein the sub-region grouped into the region of interest is dynamically changed corresponding to a size variation of the region of interest.  
   
   
       9 . A coding method for motion-image data according to  claim 1 , wherein the image frames constituting the motion-image data are compressed each by JPEG2000.  
   
   
       10 . A computer program for letting a computer execute a coding method for motion-image data according to  claim 1 .  
   
   
       11 . A recording medium storing a computer program for letting a computer execute a coding method for motion-image data according to  claim 1 .  
   
   
       12 . A two-way interactive system for mutually presenting an image of an interlocutor photographed, to a partner interlocutor through predetermined transmission means to implement an interaction between the interlocutor and the partner interlocutor, wherein image frames constituting motion-image data transmitted and received through the transmission means are coded by a coding method for motion-image data according to  claim 1 .  
   
   
       13 . A two-way interactive system according to  claim 12 , wherein the region of interest is set for a personal image of the interlocutor displayed for adjustment of a display position.  
   
   
       14 . A two-way interactive system according to  claim 12 , wherein compression levels and presence/absence of encryption of the sub-regions are set together with the setting of the region of interest.  
   
   
       15 . A decoding method for motion-image data in which for each of the image frames compressed by a coding method for motion-image data according to  claim 4 , coded data of each sub-region forming the image frame is decoded and in which the sub-regions thus decoded are combined to generate a new image frame, the decoding method comprising the steps of: 
 decoding coded data compressed as a sub-region grouped into the region of interest;    preparing as a sub-region grouped into the region of no interest, a corresponding region of another image frame previously stored after decoded; and    combining the decoded sub-region grouped into the region of interest, with the corresponding region of the other image frame prepared, to generate a display image frame.    
   
   
       16 . A computer program for letting a computer execute a decoding method for motion-image data according to  claim 15 .  
   
   
       17 . A recording medium storing a computer program for letting a computer execute a decoding method for motion-image data according to  claim 15 .  
   
   
       18 . A two-way interactive system for mutually presenting an image of an interlocutor photographed, to a partner interlocutor through predetermined transmission means to implement an interaction between the interlocutor and the partner interlocutor, wherein coded data of image frames constituting motion-image data transmitted and received through the transmission means is decoded by a decoding method for motion-image data according to  claim 15 .  
   
   
       19 . A terminal equipment applicable to a two-way interactive system for mutually presenting an image of an interlocutor photographed, to a partner interlocutor through predetermined transmission means to implement an interaction between the interlocutor and the partner interlocutor, comprising at least a display device for displaying an image of the partner interlocutor, and an image taking unit for taking the image of the interlocutor located in front of the display device, the terminal equipment comprising: 
 a controller for implementing a coding method for motion-image data according to  claim 1;  and    an input/output unit for sending coded data compressed by the controller, to the transmission means.    
   
   
       20 . A terminal equipment of the two-way interactive system according to  claim 19 , further comprising input means for setting the region of interest for the personal image of the interlocutor displayed for adjustment of a display position on the display device.  
   
   
       21 . A terminal equipment of the two-way interactive system according to  claim 19 , wherein the input means retrieves information about compression levels of the sub-regions and presence/absence of encryption thereof, together with the setting of the region of interest.  
   
   
       22 . A terminal equipment of the two-way interactive system according to  claim 19 , wherein the controller receives image data compressed by a coding method for motion-image data according to  claim 4  and transmitted to the transmission means, through the input/output unit, decodes coded data of each of the sub-regions constituting the image data, and combines the sub-regions decoded, with corresponding regions of another image frame prepared in advance, to generate a display image frame.  
   
   
       23 . A coding method for motion-image data in which each of image frames constituting motion-image data is sequentially compressed along a time axis, the coding method comprising the steps of: 
 setting a virtual image frame comprised of a plurality of sub-regions, as an image frame to be coded:    allocating one selected from at least one of a plurality of sub-images obtained by dividing an image frame to be coded out of the image frames constituting the motion-image data, and a clipped image obtained from another information source different from the motion-image data, to each of the plurality of sub-regions constituting the virtual image frame; and    individually compressing each of the images allocated to the plurality of sub-regions constituting the virtual image frame, according to a coding level set for each of the plurality of sub-regions, thereby generating coded data of each virtual image frame including plural types of image information.    
   
   
       24 . A coding method for motion-image data according to  claim 23 , wherein each of the plurality of sub-regions is grouped into either of a region of interest set in the virtual image frame and a region of no interest different from the region of interest, and 
 wherein each of the plurality of sub-regions is compressed so that a code length of a sub-region grouped into the region of interest is larger than a code length of a sub-region grouped into the region of no interest.    
   
   
       25 . A coding method for motion-image data according to  claim 24 , wherein a sub-region in which a motion of an image is detected, out of the plurality of sub-regions, is grouped into the region of interest.  
   
   
       26 . A coding method for motion-image data according to  claim 23 , wherein coded data of an image allocated to at least one of the plurality of sub-regions constituting the virtual image frame is further encrypted.  
   
   
       27 . A coding method for motion-image data according to  claim 23 , wherein in a process of coding at least one of the plurality of sub-regions, the code length of the sub-region is  0  during a certain period of time.  
   
   
       28 . A coding method for motion-image data according to  claim 23 , wherein the virtual image frame is compressed each by JPEG2000.  
   
   
       29 . A computer program for letting a computer execute a coding method for motion-image data according to  claim 23 .  
   
   
       30 . A recording medium storing a computer program for letting a computer execute a coding method for motion-image data according to  claim 23 .  
   
   
       31 . A two-way interactive system for mutually presenting an image of an interlocutor photographed, to a partner interlocutor through predetermined transmission means to implement an interaction between the interlocutor and the partner interlocutor, wherein image frames constituting motion-image data transmitted and received through the transmission means are coded by a coding method for motion-image data according to  claim 23 .  
   
   
       32 . A terminal equipment applicable to a two-way interactive system for mutually presenting an image of an interlocutor photographed, to a partner interlocutor through predetermined transmission means to implement an interaction between the interlocutor and the partner interlocutor, comprising at least a display device for displaying an image of the partner interlocutor, and an image taking unit for taking the image of the interlocutor located in front of the display device, the terminal equipment comprising: 
 a controller for implementing a coding method for motion-image data according to  claim 23;  and    an input/output unit for sending coded data compressed by the controller, to the transmission means.    
   
   
       33 . A terminal equipment of the two-way interactive system according to  claim 32 , further comprising input means for retrieving information about compression levels of the sub-regions and presence/absence of encryption thereof.  
   
   
       34 . A terminal equipment of the two-way interactive system according to  claim 29 , wherein the controller receives image data compressed by the coding method for motion-image data according to  claim 27  and transmitted to the transmission means, through the input/output unit, decodes coded data of each of the sub-regions constituting the image data, and combines the decoded sub-regions with an image prepared instead of the sub-region having the code length of 0, to generate display image data.