Hi,

Is there a function to blur an entire fpimage or a rectangular area?

Mattias

Not to my knowledge.

Michael.

Mattias Gaertner wrote

Hi, Is there a function to blur an entire fpimage or a rectangular area?

Not a direct function of Tfpimage, but is very easily accomplished using fpcanvas and the various Interpolation methods.

Graeme Geldenhuys hat am 31. Mai 2012 um 12:59
geschrieben:

Can you give an example or some pseudocode?

Mattias

Bgrabitmap for Lazarus has such filters as far as I know. You may use the algoritms I suppose.

"S.Anil Yilmaz" hat am 31. Mai 2012 um 16:39
geschrieben:

Bgrabitmap for Lazarus has such filters as far as I know. You may use the algoritms I suppose.

Thanks.

It has some nice blur algorithms.

But as far as I can see:
BGRA is RGBA 8bit, I need up to 16 bit gray scale. FilterBlur allocates a copy of an image. I have big images, so I would like to avoid that.

FilterBlur seems to require runtime O(Width*Height*Radius^2). I need Radius 20, so this would be quite slow.

Mattias

Mattias Gaertner 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.

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

You can find more examples in the ExtInterpolation.pp unit.

Michael.

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

fpc has now a new unit fpimggauss, with a normal Gaussian blur and a fast binominal Gaussian blur.

Mattias