HOW TO: Highlight part of image using region and simple processing

If the bitmap has a region, many LEADTOOLS processing functions act on the region instead of the full image.
This code sample shows how to add emphasis to part of the image by dimming out the rest of the image.
The C# code is simply this:

img.AddRoundRectangleToRegion(null, new LeadRect(80, 80, 400, 200), new LeadSize(90, 90), RasterRegionCombineMode.SetNot);
ChangeIntensityCommand changeIntensity = new ChangeIntensityCommand(-300);
changeIntensity.Run(img);

Where img is a RasterImage.
The code defines a region for all parts outside the emphasis area then reduces the intensity of these parts.

The attached image shows how the bitmap looks before processing and after.