Omnidirectional image processing method and device

An omnidirectional image processing method, comprising the following steps:

• expressing at least one image region in an omnidirectional image by the following mapping relationship, wherein the mapping relationship between a position (x, y) in the image region and a position (θ, φ) on a sphere is:
• x and φ are in linear relationship, and y and
• θ
• tan
• -
• 1
• ⁢
• cos
• ⁢
• ⁢
• φ
• are in linear relationship,
• where x represents a first dimensional coordinate position of the region in the omnidirectional image, y represents a second dimensional coordinate position of the region in the omnidirectional image, φ represents a longitude position of the sphere, θ represents a latitude position of the sphere, a line mapped to the sphere by a first dimensional coordinate axis is an equator line, and a line mapped to the sphere by a second dimensional coordinate axis is a prime meridian;
• coding and writing the omnidirectional image expressed by the mapping relationship to a code stream;
• and
• writing format information of the mapping relationship to the code stream.

An omnidirectional image processing method, comprising:

• decoding a code stream to obtain omnidirectional image coding format information;
• and
• determining mapping relationships between a position (x1, y1) in a region 1 and a position (x2, y2) in a region 2 and their respective corresponding positions (θ1, φ1) and (θ2, φ2) on a sphere according to the format information since at least one pair of adjacent regions, i.e. the region 1 and the region 2, is present in a decoded omnidirectional image, wherein the mapping relationships are:
• x1 and φ1 are in linear relationship, and y1 and
• θ
• ⁢
• 1
• tan
• -
• 1
• ⁢
• cos
• ⁢
• ⁢
• φ
• ⁢
• ⁢
• 1
• are in linear relationship;
• x2 and φ2 are in linear relationship, and y2 and
• θ
• ⁢
• 2
• tan
• -
• 1
• ⁢
• cos
• ⁢
• ⁢
• φ2
• are in linear relationship,
• where x1 represents a first dimensional coordinate position of the region 1 in the omnidirectional image, y1 represents a second dimensional coordinate position of the image region 1, φ1 represents a longitude position of the sphere corresponding to the position (x1, y1) in the region 1 in the omnidirectional image, and θ1 represents a latitude position of the sphere corresponding to the position (x1, y1) in the region 1 in the omnidirectional image;
• x2 represents a first dimensional coordinate position of the region 2 in the omnidirectional image, y2 represents a second dimensional coordinate position of the region 2 in the omnidirectional image, φ2 represents a longitude position of the sphere corresponding to the position (x2, y2) in the image region 2, and θ2 represents a latitude position of the sphere corresponding to the position (x2, y2) in the region 2 in the omnidirectional image;
• and a line mapped to the sphere by a first dimensional coordinate axis of the region 1 is the same as a line mapped to the sphere by a first dimensional coordinate axis of the region 2, and is an equator line of the sphere.

An omnidirectional image processing device, comprising the following modules:

• a format information extraction module, wherein input of the format information extraction module is a coding code stream, output of the format information extraction module is omnidirectional image format information, and the module decodes the coding code stream to obtain the omnidirectional image format information;
• and
• a position mapping module, wherein input of the position mapping module is the omnidirectional image format information, output of the position mapping module is a mapping relationship between a position (x, y) in at least one region in an omnidirectional image obtained by decoding the code stream and a position (θ, φ) on a sphere, and the mapping relationship is:
• x and φ are in linear relationship, and y and
• θ
• tan
• -
• 1
• ⁢
• cos
• ⁢
• ⁢
• φ
• are in linear relationship,
• where x represents a first dimensional coordinate position of the region in the omnidirectional image, y represents a second dimensional coordinate position of the region in the omnidirectional image, φ represents a longitude position of the sphere, θ represents a latitude position of the sphere, a line mapped to the sphere by a first dimensional coordinate axis is an equator line, and a line mapped to the sphere by a second dimensional coordinate axis is a prime meridian.

An omnidirectional image processing device, comprising the following modules:

• a position mapping module, wherein output of the position mapping module is omnidirectional image format information, and a mapping relationship between a position (x, y) in at least one region in an omnidirectional image and a position (θ, φ) on a sphere is determined in the module as:
• x and φ are in linear relationship, and y and
• θ
• tan
• -
• 1
• ⁢
• cos
• ⁢
• ⁢
• φ
• are in linear relationship,
• where x represents a first dimensional coordinate position of the region in the omnidirectional image, y represents a second dimensional coordinate position of the region in the omnidirectional image, φ represents a longitude position of the sphere, θ represents a latitude position of the sphere, a line mapped to the sphere by a first dimensional coordinate axis is an equator line, and a line mapped to the sphere by a second dimensional coordinate axis is a prime meridian;
• and
• a format information and image coding module, wherein input of the format information and image coding module is the omnidirectional image format information and the omnidirectional image expressed by the mapping relationship determined by the format information, output of the format information and image coding module is a code stream comprising the omnidirectional image and the format information of the omnidirectional image, and the module codes and writes the omnidirectional image and the format information to the code stream.