||You can do this with Spatial Analyst.
See "An overview of the Generalization tools" in the online help for an introductory discussion of the kinds of tools you will most likely want to use:
You will probably want to use Nibble. Nibble allows selected areas of a raster to be assigned the value of their nearest neighbor. This is useful for editing areas of a raster where the data is known to be erroneous.
You need to create another grid, called a MASK, with the NODATA value in each of the cells you want to replace. You can do this with the CON tool. Con performs a conditional if/else evaluation on each of the input cells of an input raster.
You can use Nibble and Con at the command line which means they can also be used in a script.
See "HowTo: Repeat-run a geoprocessing tool-batch style processing" for help on writing a script that loops through your images.
Refer to the product documentation and/or the help for more information about spatial analyst, geoprocessing and scripting.
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