Device and method for dynamic range expansion in a virtual reality scene
A lower dynamic range visual content ( 21 ) of a virtual reality or VR scene represented in a curved shape form is adapted to a higher dynamic range display of the virtual reality scene. At least two planar key views ( 230 ) of the VR scene area obtained at least two parameter values ( 240 ) respectively associated with those planar key views are obtained, corresponding to at least one parameter adapted to expand a dynamic range of a visual content, and a higher dynamic range visual content ( 22 ) corresponding to the lower dynamic range visual content in at least part of the VR scene extending beyond the planar key views is determined, based on the parameter values. Applications to Inverse Tone Mapping.
1. A method for displaying content of a virtual reality scene in a virtual reality display device, wherein a set of key views is associated with the virtual reality scene and parameter values being associated with the key views, the key views being located at different positions in the virtual reality scene, the method comprising:
determining a current viewing position of a user of the virtual reality display device;
determining a dynamic range expansion function based on the current viewing position and on at least two elementary range expansion functions being associated with respectively at least two key views selected among the set of key views associated with the virtual reality scene, the dynamic range expansion function being determined based on parameter values associated with the at least two key views;
applying the dynamic range expansion function to an area of the content of the virtual reality scene visible to the user from the current viewing position to produce a range-expanded area; and
displaying the range-expanded area on the virtual reality display device.
2. The method of claim 1 , wherein the at least two key views are selected based on distance to the current viewing position.
3. The method of claim 2 , wherein the range expansion function is determined by a weighting based on distances between the at least two key views and the current viewing position.
4. The method of claim 3 , wherein the virtual reality scene is temporally varying as a video content, the method further comprising:
extracting at least two shots from the video content,
extracting one single representative frame from each of the shots, and
in each of the representative frames:
obtaining the key views and the associated parameter values, and
determining a higher dynamic range visual content from the key views and associated parameter values,
in other frames than the representative frames in any of the shots, determining the higher dynamic range visual content based on positions of the key views and on the associated parameter values as obtained for the representative frame of the shot.
5. A virtual reality display device for displaying content of a virtual reality scene, wherein a set of key views is associated with the virtual reality scene and parameter values being associated with the key views, the key views being located at different positions in the virtual reality scene, comprising:
at least one processor configured to:
determine a current viewing position of a user of the virtual reality display device;
determine a dynamic range expansion function based on the current viewing position and on at least two elementary range expansion functions being associated with respectively at least two key views selected among the set of key views associated with the virtual reality scene, the dynamic range expansion function being determined based on parameter values associated with the at least two key views;
apply the dynamic range expansion function to an area of the content of the virtual reality scene visible to the user from the current viewing position to produce a range-expanded area; and
a display configured to display the range-expanded area.
6. The device of claim 5 , wherein the at least two key views are selected based on distance to the current viewing position.
7. The device of claim 6 , wherein the range expansion function is determined by a weighting based on distances between the at least two key views and the current viewing position.
8. The device of claim 7 , wherein the virtual reality scene is temporally varying as a video content, and the at least one processor is further configured to:
extract at least two shots from the video content,
extract one single representative frame from each of the shots, and
in each of the representative frames:
obtain the key views and the associated parameter values, and
determine a higher dynamic range visual content from the key views and associated parameter values,
in other frames than the representative frames in any of the shots, determine the higher dynamic range visual content based on positions of the key views and on the associated parameter values as obtained for the representative frame of the shot.
9. A non-transitory machine readable medium having stored thereon machine executable instructions that, when executed on a processor, display content of a virtual reality scene in a virtual reality display device, wherein a set of key views is associated with the virtual reality scene and parameter values being associated with the key views, the key views being located at different positions in the virtual reality scene, the instructions causing the processor to:
determine a current viewing position of a user of the virtual reality display device;
determine a dynamic range expansion function based on the current viewing position and on at least two elementary range expansion functions being associated with respectively at least two key views selected among the set of key views associated with the virtual reality scene, the dynamic range expansion function being determined based on parameter values associated with the at least two key views;
apply the dynamic range expansion function to an area of the content of the virtual reality scene visible to the user from the current viewing position to produce a range-expanded area; and
display the range-expanded area on the virtual reality display device.
10. The non-transitory machine readable medium of claim 9 , wherein the at least two key views are selected based on distance to the current viewing position.
11. The non-transitory machine readable medium of claim 10 , wherein the range expansion function is determined by a weighting based on distances between the at least two key views and the current viewing position.
12. The non-transitory machine readable medium of claim 11 , wherein the virtual reality scene is temporally varying as a video content, and the instructions further cause the processor to:
extract at least two shots from the video content,
extract one single representative frame from each of the shots, and
in each of the representative frames:
obtain the key views and the associated parameter values, and
determine a higher dynamic range visual content from the key views and associated parameter values,
in other frames than the representative frames in any of the shots, determine the higher dynamic range visual content based on positions of the key views and on the associated parameter values as obtained for the representative frame of the shot.