Method and device for mapping a hdr picture to a sdr picture and corresponding sdr to hdr mapping method and device
OwnerSebastien LASSERRE, Fabrice LELEANNEC +1inventors
InventorsSebastien LASSERRE, Fabrice LELEANNEC, Patrick LOPEZ
Life of this patent
Estimating the term…
Abstract
A method is disclosed that comprises mapping a high-dynamic range luminance picture to a standard-dynamic range luminance picture based on a backlight value Bac associated with the high-dynamic range luminance picture.
Claims16
A method comprising mapping a high-dynamic range luminance picture to a standard-dynamic range luminance picture based on a current backlight value representative of an average brightness of said high-dynamic range luminance picture comprising:
- determining a mapping function from a set of at least two mapping functions based on said current backlight value;
- and
- mapping the high-dynamic range luminance picture to a standard-dynamic range luminance picture using the determined mapping function, wherein each mapping function g(Bai, Y) of said set is associated with a different backlight value and is defined as f(Y/Bai)/N(Bai) where N(Bai)=f(PHDR/Bai)/MSDR with PHDR being a high-dynamic range peak brightness and MSDR being a maximum codeword value of the standard-dynamic range luminance picture and where
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- Ϛ
-
- (
- z
- )
- z
-
- [
- [
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- ζ
-
- (
- z
- )
- /
- z
- ]
- ]
- and ζ(z) is a decreasing function.
A method comprising mapping a standard-dynamic range luminance picture to a high-dynamic range luminance picture based on a current backlight value representative of an average brightness of said high-dynamic range luminance picture, comprising:
- determining a mapping function from a set of at least two mapping functions based on said current backlight value;
- and
- mapping the standard-dynamic range luminance picture to a high-dynamic range luminance picture using the determined mapping function, wherein each mapping function g−1(Bai, L) of said set is associated with a different backlight value and is defined as Bai*f−1(L*N(Bai)) where N(Bai)=f(PHDR/Bai)/MSDR with PHDR being a high-dynamic range peak brightness and MSDR being a maximum codeword value of the standard-dynamic range luminance picture and where
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- Ϛ
-
- (
- z
- )
- z
-
- [
- [
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- ζ
-
- (
- z
- )
- /
- z
- ]
- ]
- and ζ(z) is a decreasing function.
A device configured to map a high-dynamic range luminance picture to a standard-dynamic range luminance picture based on a current backlight value Bac representative of an average brightness of said high-dynamic range luminance picture, comprising at least a processor configured to:
- determine a mapping function from a set of at least two mapping functions based on said current backlight value;
- and
- map the high-dynamic range luminance picture to a standard-dynamic range luminance picture using the determined mapping function, wherein each mapping function g(Bai, Y) of said set is associated with a different backlight value and is defined as f(Y/Bai)/N(Bai) where N(Bai)=f(PHDR/Bai)/MSDR with PHDR being a high-dynamic range peak brightness and MSDR being a maximum codeword value of the standard-dynamic range luminance picture and where
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- Ϛ
-
- (
- z
- )
- z
-
- [
- [
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- ζ
-
- (
- z
- )
- /
- z
- ]
- ]
- and ζ(z) is a decreasing function.
A device configured to map a standard-dynamic range luminance picture to a high-dynamic range luminance picture based on a current backlight value representative of an average brightness of said high-dynamic range luminance picture, comprising at least a processor configured to:
- determine a mapping function from a set of at least two mapping functions based on said current backlight value;
- and
- map the standard-dynamic range luminance picture to a high-dynamic range luminance picture using the determined mapping function, wherein each mapping function g−1(Bai, L) of said set is associated with a different backlight value and is defined as Bai*f−1(L*N(Bai)) where N(Bai)=f(PHDR/Bai)/MSDR with PHDR being a high-dynamic range peak brightness and MSDR being a maximum codeword value of the standard-dynamic range luminance picture and where
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- Ϛ
-
- (
- z
- )
- z
-
- [
- [
- f
-
- (
- z
- )
- =
- exp
-
- ∫
- ζ
-
- (
- z
- )
- /
- z
- ]
- ]
- and ζ(z) is a decreasing function.
Dependencies are inferred from the claim text.