text: #import "GPUImageFilter.h"
  
  @interface GPUImageBrightnessFilter : GPUImageFilter
  {
      GLint brightnessUniform;
  }
  
  // Brightness ranges from -1.0 to 1.0, with 0.0 as the normal level
  @property(readwrite, nonatomic) CGFloat brightness; 
  
  @end
  