Method for rendering a current image on a head-mounted display, corresponding apparatus, computer program product, and computer readable carrier medium

1. A method for rendering a current image on a head-mounted display, said current image being acquired by an image capturing device mounted on a moving object, the method comprising:

obtaining a capturing roll angle, representative of a roll angle of said image capturing device for the acquisition of said current image;

determining a viewing roll angle, representative of a current roll angle of the head of a user of said head-mounted display, called a current viewing roll angle;

comparing said capturing roll angle and said current viewing roll angle and activating a detection flag if the difference between the capturing roll angle and the current viewing roll angle is lower than a determined threshold;

rotating said current image by a rotational angle, delivering a current rotated image, said rotational angle being determined as a function of said capturing roll angle, of said current viewing roll angle, and of said detection flag; and

rendering said current rotated image.

2. The method of claim 1 , wherein said rotational angle is obtained as a function of said current viewing roll angle, if said detection flag is not activated.

3. The method of claim 2 , wherein said rotational angle is equal to said current viewing roll angle, if said detection flag is not activated.

4. The method according to claim 1 , wherein said detection flag is deactivated on user request or if said capturing roll angle is null.

5. The method according to claim 1 , wherein rendering said current rotated image further comprises rendering a graphical indicator, said graphical indicator being determined as a function of said current viewing roll angle and said capturing roll angle.

6. The method of claim 5 , wherein said graphical indicator comprises a background part representative of said capturing roll angle and a foreground part representative of said current viewing roll angle.

7. The method of claim 1 , wherein said rotational angle is equal to said capturing roll angle minus said current viewing roll angle, if said detection flag is activated.

8. An apparatus for rendering a current image on a head-mounted display, said current image being acquired by an image capturing device mounted on a moving object, the apparatus comprising:

a storage unit that stores program instructions and data; and

a processor coupled to the storage unit, the processor configured to:

obtain a capturing roll angle, representative of a roll angle of said image capturing device for the acquisition of said current image;

determine a viewing roll angle, representative of a current roll angle of the head of a user of said head-mounted display, called a current viewing roll angle;

compare said capturing roll angle and said current viewing roll angle and activate a detection flag if the difference between the capturing roll angle and the current viewing roll angle is lower than a determined threshold;

rotate said current image by a rotational angle and produce a current rotated image, said rotational angle being determined as a function of said capturing roll angle, of said current viewing roll angle, and of said detection flag; and

provide said current rotated image for display.

9. The apparatus of claim 8 , wherein said rotational angle is obtained as a function of said current viewing roll angle, if said detection flag is not activated.

10. The apparatus of claim 9 , wherein said rotational angle is equal to said current viewing roll angle, if said detection flag is not activated.

11. The apparatus according to claim 8 , wherein the processor is further configured to deactivate said detection flag on user request or if said capturing roll angle is null.

12. The apparatus according to claim 8 , wherein the processor is further configured to render a graphical indicator, said graphical indicator being determined as a function of said current viewing roll angle and said capturing roll angle.

13. The apparatus of claim 8 , wherein said rotational angle is equal to said capturing roll angle minus said current viewing roll angle, if said detection flag is activated.

14. A non-transitory computer-readable medium comprising a computer program product recorded thereon and capable of being run by a processor, including program code instructions for implementing a method comprising:

obtaining a capturing roll angle, representative of a roll angle of said image capturing device for the acquisition of said current image;

determining a viewing roll angle, representative of a current roll angle of the head of a user of said head-mounted display, called a current viewing roll angle;

comparing said capturing roll angle and said current viewing roll angle and activating a detection flag if the difference between the capturing roll angle and the current viewing roll angle is lower than a determined threshold;

rotating said current image by a rotational angle, delivering a current rotated image, said rotational angle being determined as a function of said capturing roll angle, of said current viewing roll angle, and of said detection flag; and

rendering said current rotated image.

15. An apparatus, comprising:

an input device that receives a current image and obtains a capturing roll angle, representative of a roll angle of an image capturing device for the acquisition of said current image;

a processor, coupled to the input device, the processor determining a viewing roll angle, representative of a current roll angle of the head of a user of said apparatus, called a current viewing roll angle, the processor comparing said capturing roll angle and said current viewing roll angle and activating a detection flag if the difference between the capturing roll angle and the current viewing roll angle is lower than a determined threshold, the processor additionally rotating said current image by a rotational angle and producing a current rotated image for display, said rotational angle being determined as a function of said capturing roll angle, of said current viewing roll angle, and of said detection flag; and

an output device, coupled to the processor, the output device displaying said current rotated image.