at can't be a null pointer, so the condition was always false, and
a nonsensical pattern like "image.png%00d" was being inferred.

CMake's get_filename_component with NAME_WE parameters, interprets first period as start of extension. For. e.g file name with out extension of 'this.is.a.text.file.txt' will be taken as 'this'. Hence using NAME with regex replacement to get 'this.is.a.text.file'

Also, I made a separate macro for the current function name, which
helps simplify a lot of code that uses it.

Cleaned up adaptive bilateral filtering, added support for gaussian interpolation, updated sample and docs