Systems and methods for adjusting video processing curves for high dynamic range images
Systems and methods for adjusting video processing curves are disclosed herein. In one embodiment a method for applying an adjustment to an original curve derived from a set of input image data is disclosed, comprising: receiving a set of input image data to be adjusted; calculating an original curve from the set of input image data; receiving an adjustment curve, the adjustment curve based upon a desired image parameter; and applying the adjustment curve to the original curve to produce a resulting curve. In another embodiment, a display management unit (DMU) comprising a processor is disclosed that, upon receiving a set of input image data, processes the original curve according to: calculating an original curve from the set of input image data; receiving an adjustment curve, the adjustment curve based upon a desired image parameter; and applying the adjustment curve to the original curve to produce a resulting curve.
1. A method for applying an adjustment to an original luminance mapping curve or to an original chrominance mapping curve derived from a set of input image data, comprising:
receiving a set of input image data to be adjusted;
calculating an original luminance mapping curve and/or an original chrominance mapping curve from the set of input image data;
receiving an adjustment curve, the adjustment curve being based upon a scaling factor representing an ambient illumination of a viewing environment and/or user preferences, wherein the user preferences comprise user preferences regarding one of saturation, brightness and contrast of a final image; and
applying the adjustment curve to one original mapping curve to produce a resulting mapping curve used for rendering a final image based on the resulting mapping curve, wherein the adjsutment curve is calculated as:
f s ( x )=a Saturation Scale Function
C′ T =C T ×f S ( I )
C′ P =C P ×f S ( I )
wherein C T and C P are chroma components of a source image, and C′ T and C′ P are chroma components of a target image and I is a luminance component, wherein optionally the Saturation Scale Function may be a function of one of ambient conditions and the user preferences.
2. The method according to claim 1 , wherein the set of input image data comprises one of an image, a frame of video data and a scene in a video to be displayed by a display device in the viewing environment, wherein the scene in the video comprises multiple consecutive frames of video data.
3. The method according to claim 1 , wherein calculating the original luminance mapping curve from the set of input image data further comprises calculating the original luminance mapping curve from one or more tone mapping parameters.
4. The method according to claim 1 , wherein calculating the original chrominance mapping curve from the set of input image data further comprises calculating the original chrominance mapping curve from one or more saturation mapping parameters.
5. The method according to claim 1 , wherein applying the adjustment curve to one original curve comprises applying an operation to said original curve employing the adjustment curve, wherein optionally the operation comprises one of addition, subtraction, multiplying, dividing and convolving.
6. The method according to claim 1 , wherein the adjustment curve is calculated as:
C
=
SB
100
max
(
B
)
wherein S is the scaling factor representing the ambient illumination and B is a function dependent on input pixel values, assumed original adapting luminance and a function based on an Electro-Optical Transfer Function, EOTF.
7. The method according to claim 1 , wherein the adjustment curve is calculated as:
f
(
x
)
=
ae
-
(
x
-
b
)
2
2
c
2
wherein x comprises an input pixel value, a comprises a change in brightness requested based on user preferences, b comprises the mean and c comprises the min ( max−mean, mean−min ) luminance values in an image, a frame of video data or a scene in a video, wherein the scene in the video comprises multiple consecutive frames of video data.
8. The method according to claim 1 , wherein the adjustment curve is calculated as the negative of the derivative of
f
(
x
)
=
ae
-
(
x
-
b
)
2
2
c
2
,
wherein x comprises an input pixel value, a comprises a change in brightness requested based on user preferences, b comprises the mean and c comprises the min ( max−mean, mean−min ) luminance values in an image, a frame of video data or a scene in a video, wherein the scene in the video comprises multiple consecutive frames of video data.
9. The method according to claim 1 , wherein the method further comprises:
sending the resulting mapping curve to a display for rendering the final image based on the resulting mapping curve.
10. A display management unit, DMU, comprising a processor that, upon receiving a set of input image data, processes an original luminance or chrominance mapping curve according to:
calculating an original luminance mapping or chrominance mapping curve from the set of input image data;
receiving an adjustment curve, the adjustment curve being based upon a scaling factor representing an ambient illumination of a viewing environment and/or user preferences; and
applying the adjustment curve to the original mapping curve to produce a resulting curve for rendering a final image based on the resulting curve, wherein the adjustment curve is calculated as:
f s ( x )=some Saturation Scale Function
C′ T =C T ×f S ( I )
C′ P =C P ×f S ( I )
wherein C T and C P are chroma components of a source image, and C′ T and C′ P are chroma components of a target image and I is a luminance component, wherein optionally the Saturation Scale Function may be a function of one of ambient conditions and the user preferences.
11. The DMU according to claim 10 , wherein the user preferences comprise user preferences regarding one of saturation, brightness and contrast of the final image.
12. The DMU according to claim 11 , wherein applying the adjustment curve to the original curve comprises applying an operation to the original curve employing the adjustment curve, wherein optionally the operation comprises one of addition, subtraction, multiplying, dividing and convolving.
13. The DMU according to claim 10 , wherein the DMU sends the resulting curve to a display for rendering a final image based on the resulting curve.