public StretchColorizerDefinition( 
   int bandIndex,
   RasterStretchType stretchType,
   double gamma,
   CIMColorRamp colorRamp
)

await QueuedTask.Run(async () =>
{
  // Check if the Stretch colorizer can be applied to the raster layer.
  if (rasterLayer.GetApplicableColorizers().Contains(RasterColorizerType.StretchColorizer))
  {
    // Create a new Stretch Colorizer Definition specifying parameters 
    // for band index, stretch type, gamma and color ramp.
    StretchColorizerDefinition stretchColorizerDef_custom =
      new StretchColorizerDefinition(1, RasterStretchType.ESRI, 2, colorRamp);
    // Create a new stretch colorizer using the colorizer definition created above.
    CIMRasterStretchColorizer newStretchColorizer_custom =
      await rasterLayer.CreateColorizerAsync(stretchColorizerDef_custom) as CIMRasterStretchColorizer;
    // Set the new colorizer on the raster layer.
    rasterLayer.SetColorizer(newStretchColorizer_custom);
  }
});

await QueuedTask.Run(async () =>
{
  // Get the image sub-layer from the mosaic layer.
  ImageMosaicSubLayer mosaicImageSubLayer = mosaicLayer.GetImageLayer();
  // Check if the Stretch colorizer can be applied to the image sub-layer.
  if (mosaicImageSubLayer.GetApplicableColorizers().Contains(RasterColorizerType.StretchColorizer))
  {
    // Create a new Stretch colorizer definition specifying parameters
    // for band index, stretch type, gamma and color ramp.
    StretchColorizerDefinition stretchColorizerDef_custom =
      new StretchColorizerDefinition(1, RasterStretchType.ESRI, 2, colorRamp);
    // Create a new stretch colorizer using the colorizer definition created above.
    CIMRasterStretchColorizer newStretchColorizer_custom =
      await mosaicImageSubLayer.CreateColorizerAsync(stretchColorizerDef_custom) as CIMRasterStretchColorizer;
    // Set the new colorizer on the image sub-layer.
    mosaicImageSubLayer.SetColorizer(newStretchColorizer_custom);
  }
});

await QueuedTask.Run(async () =>
{
  // Check if the Stretch colorizer can be applied to the image service layer.
  if (isLayer.GetApplicableColorizers().Contains(RasterColorizerType.StretchColorizer))
  {
    // Create a new Stretch Colorizer Definition specifying parameters
    // for band index, stretch type, gamma and color ramp. 
    StretchColorizerDefinition stretchColorizerDef_custom =
      new StretchColorizerDefinition(1, RasterStretchType.ESRI, 2, colorRamp);
    // Create a new stretch colorizer using the colorizer definition created above.
    CIMRasterStretchColorizer newStretchColorizer_custom =
      await isLayer.CreateColorizerAsync(stretchColorizerDef_custom) as CIMRasterStretchColorizer;
    // Set the new colorizer on the image service layer.
    isLayer.SetColorizer(newStretchColorizer_custom);
  }
});