text: #import "GPUImageGaussianBlurFilter.h"
  
  @interface GPUImageBilateralFilter : GPUImageGaussianBlurFilter
  {
      CGFloat firstDistanceNormalizationFactorUniform;
      CGFloat secondDistanceNormalizationFactorUniform;
  }
  // A normalization factor for the distance between central color and sample color.
  @property(nonatomic, readwrite) CGFloat distanceNormalizationFactor;
  @end
  