Mask-based spatio-temporal dithering

Abstract

In one embodiment, a computing system may determine, a target pixel value for a pixel of a current subframe of a series of N subframes. The series of N subframes may be displayed consequently in a time domain. The system may determine an aggregated target pixel value of target pixel values of the pixel in subframes prior to the current subframe in the series of N subframes. The system may determine an aggregated actual pixel value of displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes. The system may determine an aggregated quantization error based on a difference between the aggregated target pixel value and the aggregated actual pixel value. The system may determine a compensated target pixel value based on the target pixel value and the aggregated quantization error.

1 - 20 . (canceled) 
     
     
         21 . A method comprising, by a computing system:
 determining a target pixel value for a pixel of a current subframe of a series of N subframes, wherein the series of N subframes are to be displayed consequently in a time domain;   determining an aggregated target pixel value of target pixel values of the pixel in subframes prior to the current subframe in the series of N subframes;   determining an aggregated actual pixel value of displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes;   determining an aggregated quantization error based on a difference between the aggregated target pixel value and the aggregated actual pixel value; and   determining a compensated target pixel value based on the target pixel value and the aggregated quantization error.   
     
     
         22 . The method of  claim 21 , wherein the aggregated target pixel value is determined based on the target pixel value for the pixel and a current subframe number n of the series of N subframes. 
     
     
         23 . The method of  claim 21 , wherein the aggregated actual pixel value is a sum of the displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes. 
     
     
         24 . The method of  claim 21 , further comprising:
 accessing a mask value from a dithering mask having a spatial stacking property;   determining a quantized pixel value for the pixel of the current frame based on the compensated target pixel value and the accessed mask value; and   providing the quantized pixel value for display.   
     
     
         25 . The method of  claim 24 , wherein the quantized pixel value is determined based on the compensated target pixel value and a quantization level unit corresponding a least significant bit (LSB) of a quantization range. 
     
     
         26 . The method of  claim 25 , wherein the quantized pixel value corresponds to a closest quantization level lower than the compensated target pixel value adjusted by the mask value, and wherein the quantized pixel value is determined based on a floor operation. 
     
     
         27 . The method of  claim 24 , wherein the quantized pixel value is determined based on a non-linear quantization on a quantization range comprising non-uniformly distributed quantization levels within the quantization range. 
     
     
         28 . The method of  claim 27 , wherein the quantized pixel value is determined by:
 determining a first closest quantization level lower than the compensated target pixel value;   determining a second closest quantization level greater than the compensated target pixel value;   determining a remainder of the compensated pixel value over the first closest quantization level;   comparing the remainder to the mask value accessed from the dithering mask; and
 in response to a determination that the remainder is less than the mask value, determining the quantized pixel value based on the first closest quantization level; and 
 in response to a determination that the remainder is greater than the mask value, determining the quantized pixel value based on the second closest quantization level. 
   
     
     
         29 . The method of  claim 24 , wherein the dithering mask comprises a plurality of stacked dot patterns each comprising a plurality of dots, wherein each dot of the dithering mask is associated with a threshold value, and wherein the threshold value corresponds to a lowest threshold value which has a corresponding dot pattern comprising that dot. 
     
     
         30 . The method of  claim 29 , wherein each of the plurality of stacked dot patterns corresponds to a particular grayscale level and satisfies a constraint for the spatial stacking property by comprising all dot patterns corresponding to lower grayscale levels than that particular grayscale level. 
     
     
         31 . The method of  claim 21 , further comprising:
 determining an intermediate compensated target pixel value based on a difference between (1) the aggregated target pixel value of the target pixels of the pixel of the current subframe and the previously subframes of the series of N subframes, and (2) the aggregated actual pixel value of the displayed pixel values of the pixel in the previous subframes of the series of N subframes, wherein the intermediate compensated target pixel corresponds to N times of the compensated target pixel value; and   clipping the intermediate compensated target pixel value into a range of [0, 1].   
     
     
         32 . The method of  claim 31 , wherein the compensated target pixel value is determined based on a quantization result of the intermediate compensated target pixel. 
     
     
         33 . The method of  claim 21 , further comprising:
 displaying the series of N subframes sequentially in the time domain within a pre-determined time duration, wherein the pre-determined time duration allows human visual systems to work as temporal integrators for perceiving the series of N subframes.   
     
     
         34 . One or more computer-readable non-transitory storage media embodying software that is operable when executed to:
 determine a target pixel value for a pixel of a current subframe of a series of N subframes, wherein the series of N subframes are to be displayed consequently in a time domain;   determine an aggregated target pixel value of target pixel values of the pixel in subframes prior to the current subframe in the series of N subframes;   determine an aggregated actual pixel value of displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes;   determine an aggregated quantization error based on a difference between the aggregated target pixel value and the aggregated actual pixel value; and   determine a compensated target pixel value based on the target pixel value and the aggregated quantization error.   
     
     
         35 . The media of  claim 34 , wherein the aggregated target pixel value is determined based on the target pixel value for the pixel and a current subframe number n of the series of N subframes. 
     
     
         36 . The media of  claim 34 , wherein the aggregated actual pixel value is a sum of the displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes. 
     
     
         37 . The media of  claim 34 , further embodying software that is operable to:
 access a mask value from a dithering mask having a spatial stacking property;   determine a quantized pixel value for the pixel of the current frame based on the compensated target pixel value and the accessed mask value; and   provide the quantized pixel value for display.   
     
     
         38 . A system comprising:
 one or more non-transitory computer-readable storage media embodying instructions; and   one or more processors coupled to the storage media and operable to execute the instructions to:
 determine a target pixel value for a pixel of a current subframe of a series of N subframes, wherein the series of N subframes are to be displayed consequently in a time domain; 
 determine an aggregated target pixel value of target pixel values of the pixel in subframes prior to the current subframe in the series of N subframes; 
 determine an aggregated actual pixel value of displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes; 
 determine an aggregated quantization error based on a difference between the aggregated target pixel value and the aggregated actual pixel value; and 
 determine a compensated target pixel value based on the target pixel value and the aggregated quantization error. 
   
     
     
         39 . The system of  claim 38 , wherein the aggregated target pixel value is determined based on the target pixel value for the pixel and a current subframe number n of the series of N subframes. 
     
     
         40 . The system of  claim 38 , wherein the aggregated actual pixel value is a sum of the displayed pixel values of the pixel in the subframes prior to the current subframe in the series of N subframes.