text: #import "GPUImageColorInvertFilter.h"
  
  #if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
  NSString *const kGPUImageInvertFragmentShaderString = SHADER_STRING
  (
   varying highp vec2 textureCoordinate;
   
   uniform sampler2D inputImageTexture;
   
   void main()
   {
      lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
      
      gl_FragColor = vec4((1.0 - textureColor.rgb), textureColor.w);
   }
  );                                                                    
  #else
  NSString *const kGPUImageInvertFragmentShaderString = SHADER_STRING
  (
   varying vec2 textureCoordinate;
   
   uniform sampler2D inputImageTexture;
   
   void main()
   {
       vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
       
       gl_FragColor = vec4((1.0 - textureColor.rgb), textureColor.w);
   }
   );
  #endif
  
  @implementation GPUImageColorInvertFilter
  
  - (id)init;
  {
      if (!(self = [super initWithFragmentShaderFromString:kGPUImageInvertFragmentShaderString]))
      {
  		return nil;
      }
      
      return self;
  }
  
  @end
  
  