HOW TO: Modify a small portion of a large image without loading the entire image

Sometimes you might want to make a small change to a specific area of a large image that would take up a lot of memory if loaded in its entirety.  For example, you just want to stamp some text or fill a 100x100 rectangle in a 10,000x10,000 image.  Instead of loading the entire image into memory (over 300MB at 24bpp), you can load just the tile, modify it, and then save it back to the image.  This C# 2005 example uses LEADTOOLS v16 .NET interface shows how to do this by:

1. Using the RasterCodecs.Load overload function which takes a Rectangle to load a specific portion (tile) of the image
2. Modify the tile with an ImageProcessing command such as FlipCommand
3. Use the RasterCodecs.SaveImage event to save the image row by row (using RasterImage.GetRow) so that you don't have to load the entire image into memory at one time.