<languageVersion: 1.0;>
   
  // invertRGB: A simple example to demonstrate how to invert the RGB color 
  //            space.
  kernel invertRGB
  <   namespace : "AIF";
      vendor : "Adobe Systems, Inc.";
      version : 2;
      description : "Invert the Red, Green and Blue channels of an image"; >
  {
      input image4 src;
      output float4 dst;
      
      // evaluatePixel(): The function of the filter that actually does the 
      //                  processing of the image.  This function is called once 
      //                  for each pixel of the output image.
      void
      evaluatePixel()
      {
          // Obtain the input pixel color
          float4 inputColor = sampleNearest(src, outCoord());
  
          // Calculate (1 - channel) for each of the RGB channels
          dst.rgb = float3(1.0, 1.0, 1.0) - inputColor.rgb;
          
          // set the alpha value equal to the alpha of the input
          dst.a = inputColor.a;
      }
  }