Method And Apparatus For Conversion Of HDR Signals

• US 20170006273A1
• Filed: 06/29/2016
• Published: 01/05/2017
• Est. Priority Date: 06/30/2015
• Status: Active Grant

• Current Assignee: British Broadcasting Corporation
• Original Assignee: British Broadcasting Corporation
• Inventors: Raine Cotton, Andrew David, Borer, Timothy John
• Granted Patent: US 10,455,209 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/20208 High dynamic range [HDR] image processing
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 2370/04 Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/10 Intensity circuits
• CPC Class Codes: H04N 5/202 Gamma control circuits for controlling camera response irrespective of the scene brightness H04N23/82
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86
• CPC Class Codes: H04N 9/77 Circuits for processing the brightness signal and the chrominance signal relative to each other, e.g. adjusting the phase of the brightness signal relative to the colour signal, correcting differential gain or differential phase circuits for matrixing H04N9/67

Abstract

Described are concepts, systems and techniques related to processing an input video signal intended for a first display to produce an output signal appropriate for a second display. The concepts, systems and techniques include converting using one or more transfer functions arranged to provide relative scene light values and remove or apply rendering intent of the input or output video signal, wherein the removing or applying rendering intent alters luminance.

Claims

1. A method of processing an input video signal intended for a first display to produce an output signal appropriate for a second display, comprising converting using one or more transfer functions arranged to:

provide relative scene light values; and

remove or apply rendering intent of the input or output video signal;

wherein the removing or applying rendering intent alters luminance.

2. A method according to claim 1, wherein the removing or applying rendering intent is applied to a luminance component.

3. A method according to claim 1, wherein removing or applying rendering intent is applied to RGB components without altering relative values such that colour is unchanged.

4. A method according to claim 1, further comprising scaling to convert between an absolute range and a relative range.

5. A method according to claim 1, wherein at least one of the input or output signals is a display referred signal and the rendering intent is the rendering intent of the display referred signal.

6. A method according to claim 5, wherein the output signal is a display referred signal and the removing or applying rendering intent is an opto-optical transfer function to provide the rendering intent for the display referred signal.

7. A method according to claim 5, wherein the input is a display referred signal and the removing or applying rendering intent is an inverse opto-optical transfer function to remove the rendering intent from the display referred signal.

8. A method according to claim 1, wherein one or more transfer functions are provided by a 3D-LUT having values to provide the conversion.

9. A method according to claim 1, wherein the removing or applying rendering intent is applied as a function of input RGB values according to any of:

R_d=L_peak×

R_s×

(Y_d/Y_s)

G_d=L_peak×

G_s×

(Y_d/Y_s)

B_d=L_peak×

B_s×

(Y_d/Y_s)

(a)

$\begin{array}{cc}{R}_s=R_r\times <br><br>{\left(Y_r\right)}^{\frac{1-\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}}}<br><br><br><br>G_s=G_r\times <br><br>{\left(Y_r\right)}^{\frac{1-\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}}}<br><br><br><br>B_s=B_r\times <br><br>{\left(Y_r\right)}^{\frac{1-\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}}}& \left(b\right)\end{array}$
R_r=R_s×

(Y_r/Y_s)=R_s×

Y_s<sup>γ

−

1</sup>

G_r=G_s×

(Y_r/Y_s)=G_s×

Y_s<sup>γ

−

1</sup>

B_r=B_s×

(Y_r/Y_s)=B_s×

Y_s<sup>γ

−

1</sup>

(c)

22. Apparatus being part of a studio chain comprising means arranged to undertake the method of claim 1.

10. A converter for processing an input video signal intended for a first display to produce an output signal appropriate for a second display, comprising one or more transfer functions arranged to:

provide relative scene light values; and

remove or apply rendering intent of the input or output video signal;

wherein the removing or applying rendering intent alters luminance.

11. A converter according to claim 10, wherein the removing or applying rendering intent is applied to a luminance component.

12. A converter according to claim 10, wherein the removing or applying rendering intent is applied to RGB components without altering relative values such that colour is unchanged.

13. A converter according to claim 10, further comprising means for scaling to convert between an absolute range and a relative range.

14. A converter according to of claim 10, wherein at least one of the input or output signals is a display referred signal and the rendering intent is the rendering intent of the display referred signal.

15. A converter according to claim 14, wherein the output signal is a display referred signal and the removing or applying rendering intent is an opto-optical transfer function to provide the rendering intent for the display referred signal.

16. A converter according to claim 14, wherein the input is a display referred signal and the removing or applying rendering intent is an inverse opto-optical transfer function to remove the rendering intent from the display referred signal.

17. A converter according to claim 10, wherein one or more transfer functions are provided by a 3D-LUT having values to provide the conversion.

18. A converter according to claim 10, wherein the removing or applying rendering intent is applied as a function of input RGB values according to any of:

R_d=L_peak×

R_s×

(Y_d/Y_s)

G_d=L_peak×

G_s×

(Y_d/Y_s)

B_d=L_peak×

B_s×

(Y_d/Y_s)

(a)

$\begin{array}{cc}{R}_s=R_r\times <br><br>{\left(Y_r\right)}^{\frac{1-\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}}}<br><br><br><br>G_s=G_r\times <br><br>{\left(Y_r\right)}^{\frac{1-\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}}}<br><br><br><br>B_s=B_r\times <br><br>{\left(Y_r\right)}^{\frac{1-\mathrm{\gamma <br><br>}}{\mathrm{\gamma <br><br>}}}& \left(b\right)\end{array}$
R_r=R_s×

(Y_r/Y_s)=R_s×

Y_s<sup>γ

−

1</sup>

G_r=G_s×

(Y_r/Y_s)=G_s×

Y_s<sup>γ

−

1</sup>

B_r=B_s×

(Y_r/Y_s)=B_s×

Y_s<sup>γ

−

1</sup>

(c)

19. A device comprising the converter of claim 10.

20. A receiver, set top box or display comprising the converter of claim 10.

21. A system comprising the converter of claim 10.

23. A transmitter comprising the converter of claim 10.