[fpc-pascal] fpimage blur

[Mattias Gaertner]

On Thu, 31 May 2012 20:42:35 +0100
Graeme Geldenhuys <graemeg.lists at gmail.com> wrote:

> On 31 May 2012 12:35, Mattias Gaertner <nc-gaertnma at netcologne.de> wrote:
> >
> > Can you give an example or some pseudocode?
> 
> 
> I just moved country, so don't have access to my development pc yet
> (still in shipping), so can't get hold of a working code example. So
> best I can do is code example from memory... it was something like
> this.
> 
> 
> Untested code follows...
> 
> ------------------------
> program project1;
> 
> {$mode objfpc}{$H+}
> 
> uses
>   {$IFDEF UNIX}{$IFDEF UseCThreads}
>   cthreads,
>   {$ENDIF}{$ENDIF}
>   Classes, fpcanvas, fpimage, FPReadBMP, FPWriteBMP;
> 
> {$R *.res}
> 
> type
>   { to make Initialize public, though FImage field variable is all we
> need access to }
>   TMyInterpolation = class(TMitchelInterpolation)
>   public
>     procedure Initialize(aimage: TFPCustomImage; acanvas: TFPCustomCanvas);
>        override;
>   end;
> 
> var
>   img: TFPMemoryImage;
>   inter: TMyInterpolation;
> 
> { TMyInterpolation }
> 
> procedure TMyInterpolation.Initialize(aimage: TFPCustomImage;
>   acanvas: TFPCustomCanvas);
> begin
>   inherited Initialize(aimage, acanvas);
> end;
> 
> begin
>   img := TFPMemoryImage.Create(32, 32);
>   inter := TMyInterpolation.Create;
>   try
>     img.LoadFromFile('testin.bmp');
>     inter.Initialize(img, nil);  { associate the memory image to
> interpolation class }
>     inter.Execute(0, 0, 32, 32);  { define rectangle or whole image
> and exec interpolation }
>     img.SaveToFile('testout.bmp');
>   finally
>     inter.Free;
>     img.Free;
>   end;
> end.
> 
> -------------------------
> 
> 
> I hope this gives you the general idea. As I mentioned, I have done
> something similar before, and from what I remember, it wasn't to hard
> to get working.

The interpolation is only for scaling, isn't it?
Do you mean: down sample, gaussian blur, up sample?
That would give a fast algorithm, with only a small memory need. But I
fear the results won't be pretty.

 
> Alternatively, AggPas also has many filter/blur/interpolation
> functions available. There are a few AggPas demos showing this in
> action.

Yep, Aggpas seems to have the right algorithm.
Thanks, this gives me some ideas to continue.

Mattias