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delphi good quality resizing BITMAP

I am looking for a good BITMAP resizing library (I need to resize BITMAP picture and then have to save it).
I found some poor quality results, and I am looking for something like Photoshop result (good quality interpolation).
Any clues ?

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MerijnB

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dinilud

http://www.swissdelphicenter.ch/torry/showcode.php?id=1896

dinilud

http://www.efg2.com/Lab/Library/Delphi/Graphics/ImageProcessing.htm

MerijnB

I snippet I made a while ago, as an example how to use GR32.
In this case Lanczos algorithm is used (the line where StretchTransfer() is called).
But you case use other algorithms aswell: type TStretchFilter = (sfNearest, sfLinear, sfSpline, sfLanczos, sfMitchell);

asaik Spline is used often by PhotoShop

procedure TMainForm.ResizeImage(Image: TBitmap; OutImage: TJPEGImage);
const OUT_WIDTH = 480;
OUT_HEIGHT = 360;
BACK_COLOR = clWhite;
var SourceBMP: TBitmap32;
DestBMP: TBitmap32;
StretchFactor: real;
StretchRect: TRect;
Temp: TBitmap;
begin
SourceBMP := TBitmap32.Create();
SourceBMP.Assign(Image);

DestBMP := TBitmap32.Create();
DestBMP.SetSize(OUT_WIDTH, OUT_HEIGHT);
DestBMP.Canvas.Brush.Color := BACK_COLOR;
DestBMP.Canvas.FillRect(DestBMP.BoundsRect);
DestBMP.StretchFilter := sfLanczos;

StretchRect.Left := 0;
StretchRect.Top := 0;
StretchRect.Right := Image.Width;
StretchRect.Bottom := Image.Height;

if (Image.Width > OUT_WIDTH) or (Image.Height > OUT_HEIGHT) then
begin
if (Image.Width div 4) > (Image.Height div 3) then
begin
StretchFactor := Image.Width / OUT_WIDTH;

StretchRect.Right := OUT_WIDTH;
StretchRect.Bottom := round(Image.Height / StretchFactor);
end
else
begin
StretchFactor := Image.Height / OUT_HEIGHT;

StretchRect.Bottom := OUT_HEIGHT;
StretchRect.Right := round(Image.Width / StretchFactor);
end;
end;

OffsetRect(StretchRect, (OUT_WIDTH - StretchRect.Right) div 2, (OUT_HEIGHT - StretchRect.Bottom) div 2);

StretchTransfer(DestBMP, StretchRect, DestBMP.BoundsRect, SourceBMP, SourceBMP.BoundsRect, sfLanczos, dmOpaque);

Temp := TBitmap.Create();
Temp.Width := DestBMP.Width;
Temp.Height := DestBMP.Height;

DestBMP.DrawTo(Temp.Canvas.Handle, 0, 0);

OutImage.Assign(Temp);

Temp.Free();
SourceBMP.Free();
DestBMP.Free();
end;