Patent ID: 11935492
Assignee: DOLBY LABORATORIES LICENSING CORPORATION
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 9:
10. A computer-implemented method for providing an image-dependent brightness control based on a user-defined value of an average picture level boost adjustment parameter to increase brightness in dark image portions relatively stronger than in bright image portions, the method comprising:
receiving an input image in an image dynamic range;
receiving a minimum display luminance value and a maximum display luminance value defining a display dynamic range of a target display;
generating (405) an adjusted maximum luminance value for the target display based on the average picture level boost adjustment parameter, wherein the adjusted maximum luminance value is lower than the maximum display luminance value;
generating (410) a tone-mapped image with a tone-mapping function and the input image, wherein the tone-mapping function maps the image dynamic range to the minimum display luminance value and the adjusted maximum luminance value; and
generating (415) an output image for the target display by applying a linear mapping to the tone-mapped image, wherein parameters of the linear mapping are based on the minimum display luminance value, the maximum display luminance value, and the adjusted maximum luminance value;
wherein generating the adjusted maximum luminance value (TmaxAdj) comprises computing, T
    
     max
     Adj
    
   
   =
   
    T
    ⁢
    max
    *
    
     1
     
      2
      α
     
    
   
  
  ,
 

wherein Tmax denotes the maximum display luminance value and α denotes the average picture level boost adjustment parameter;
wherein for an RGB color component in the tone-mapped image applying the linear mapping to generate a color component (RGB0) in the output image comprises computing

RGBo=RGB*m−b, 

wherein, m
  =
  
   
    
     T
     ⁢
     max
    
    -
    
     T
     ⁢
     min
    
   
   
    
     T
     
      max
      Adj
     
    
    -
    
     T
     ⁢
     min
    
   
  
 

 and

 
  b
  =
  
   
    
     
      T
      ⁢
      min
      *
      T
      ⁢
      max
     
     -
     
      T
      
       min
       2
      
     
    
    
     
      T
      
       max
       Adj
      
     
     -
     
      T
      ⁢
      min
     
    
   
   -
   
    T
    ⁢
    min, denote the parameters of the linear mapping, Tmin denotes the minimum display luminance value, Tmax denotes the maximum display luminance value, and TmaxAdj denotes the adjusted maximum luminance value.