Add filter plugin

[Boudewijn Rempt]

On Fri, 3 Aug 2012, Daniel Johannsen wrote:

> I will start by defining a new process() method and take a look at the examples on how to create proper menu entries.

That's pretty easy. Just take any existing filter (the invert example is 
quite ok) and replace the the relevant strings in the rc, desktop and 
plugin files.

> 
> Motivation comes from the importance of luminance information in paintings (ref. M. Livingstone).
> Let me suggest for future versions to extend the existing desaturation filter in order to be able to choose among several
> color-to-gray transformation algorithms ( e.g. luminance or luminosity in gimp, average, etc. ).

Oh, yes, that would be great!


> By the way, when invoking the desaturate filter in calligra version 2.4.2, there is repeatedly the message on stdout:
> krita(12176)/koffice: Lcms2 error:  12 Malformed struct in type 'desc' for tag 'dmnd'.
> Since the filter works, it is not a big issue.

That's probably caused by one of the profiles we load -- I doubt it's 
relevant, that tag is only for user information

> Congratulations and thank you very much for this fantastic painting program.

thanks! And thanks for wanting to hack on krita :-)

Boudewijn