You can do it in two ways: before blob recognition and after.
Before — just use yes another filter: http://www.aforgenet.com/framework/docs/html/4a83d944-d776-ba2c-9847-3254fe3dbfdd.htm
In response to your first question on blob recognition, I advised you to use brightness and contrasting filters:
image processing using Aforge.net >> I need the help
If you use the blob filtering using the filter referenced above, you should apply those brightness and contrasting filters before
blob filtering. Note that this blob filtering has nothing to do with blob enumeration you already know.
So, you can use this blob enumeration. You should do it after all other filters are applied
. From the AForge.NET demo application you can see the properties of each blob:
So, you can always traverse the collection of all blobs and remove the blobs you don't want for further considerations, based on whatever criteria you need.
Finally, you can combine this approach with filtering. Basically, filtering criteria can only be pretty simple (typically, by X/Y size of a block), but final selection can be based on the criteria you want, so using both approaches can be useful.