Folding a Bitmap

type
  TRGBTripleArray = array[0..10000] of TRGBTriple;
  PRGBTripleArray = ^TRGBTripleArray;
  T3x3FloatArray = array[0..2] of array[0..2] of Extended;
  
//

function Convolve(ABitmap: TBitmap; AMask: T3x3FloatArray;
  ABias: Integer): TBitmap;
var
  LRow1, LRow2, LRow3, LRowOut: PRGBTripleArray;
  LRow, LCol: integer;
  LNewBlue, LNewGreen, LNewRed: Extended;
  LCoef: Extended;
begin
  LCoef := 0;
  for LRow := 0 to 2 do
    for LCol := 0 to 2 do
      LCoef := LCoef + AMask[LCol, LRow];
  if LCoef = 0 then LCoef := 1;

  Result := TBitmap.Create;

  Result.Width := ABitmap.Width - 2;
  Result.Height := ABitmap.Height - 2;
  Result.PixelFormat := pf24bit;

  LRow2 := ABitmap.ScanLine[0];
  LRow3 := ABitmap.ScanLine[1];

  for LRow := 1 to ABitmap.Height - 2 do
  begin
    LRow1 := LRow2;
    LRow2 := LRow3;
    LRow3 := ABitmap.ScanLine[LRow + 1];

    LRowOut := Result.ScanLine[LRow - 1];

    for LCol := 1 to ABitmap.Width - 2 do
    begin
      LNewBlue :=
        (LRow1[LCol - 1].rgbtBlue * AMask[0,0]) + (LRow1[LCol].rgbtBlue * AMask[1,0]) +
        (LRow1[LCol + 1].rgbtBlue * AMask[2,0]) +
        (LRow2[LCol - 1].rgbtBlue * AMask[0,1]) + (LRow2[LCol].rgbtBlue * AMask[1,1]) +
        (LRow2[LCol + 1].rgbtBlue * AMask[2,1]) +
        (LRow3[LCol - 1].rgbtBlue * AMask[0,2]) + (LRow3[LCol].rgbtBlue * AMask[1,2]) +
        (LRow3[LCol + 1].rgbtBlue * AMask[2,2]);
      LNewBlue := (LNewBlue / LCoef) + ABias;
      if LNewBlue > 255 then
        LNewBlue := 255;
      if LNewBlue < 0 then
        LNewBlue := 0;

      LNewGreen :=
        (LRow1[LCol - 1].rgbtGreen * AMask[0,0]) + (LRow1[LCol].rgbtGreen * AMask[1,0]) +
        (LRow1[LCol + 1].rgbtGreen * AMask[2,0]) +
        (LRow2[LCol - 1].rgbtGreen * AMask[0,1]) + (LRow2[LCol].rgbtGreen * AMask[1,1]) +
        (LRow2[LCol + 1].rgbtGreen * AMask[2,1]) +
        (LRow3[LCol - 1].rgbtGreen * AMask[0,2]) + (LRow3[LCol].rgbtGreen * AMask[1,2]) +
        (LRow3[LCol + 1].rgbtGreen * AMask[2,2]);
      LNewGreen := (LNewGreen / LCoef) + ABias;
      if LNewGreen > 255 then
        LNewGreen := 255;
      if LNewGreen < 0 then
        LNewGreen := 0;

      LNewRed :=
        (LRow1[LCol - 1].rgbtRed * AMask[0,0]) + (LRow1[LCol].rgbtRed * AMask[1,0])
        + (LRow1[LCol + 1].rgbtRed * AMask[2,0]) +
        (LRow2[LCol - 1].rgbtRed * AMask[0,1]) + (LRow2[LCol].rgbtRed * AMask[1,1])
        + (LRow2[LCol + 1].rgbtRed * AMask[2,1]) +
        (LRow3[LCol - 1].rgbtRed * AMask[0,2]) + (LRow3[LCol].rgbtRed * AMask[1,2])
        + (LRow3[LCol + 1].rgbtRed * AMask[2,2]);
      LNewRed := (LNewRed / LCoef) + ABias;
      if LNewRed > 255 then
        LNewRed := 255;
      if LNewRed < 0 then
        LNewRed := 0;

      LRowOut[LCol - 1].rgbtBlue  := trunc(LNewBlue);
      LRowOut[LCol - 1].rgbtGreen := trunc(LNewGreen);
      LRowOut[LCol - 1].rgbtRed   := trunc(LNewRed);
    end;
  end;
end;

Beispiel :

procedure TForm1.Button1Click(Sender: TObject);
var
  LMask: T3x3FloatArray;
begin
  LMask[0,0] := -1;
  LMask[1,0] := -1;
  LMask[2,0] := -1;
  LMask[0,1] := -1;
  LMask[1,1] :=  8;
  LMask[2,1] := -1;
  LMask[0,2] := -1;
  LMask[1,2] := -1;
  LMask[2,2] := -1;

  Image1.Picture.Bitmap := Convolve(Image1.Picture.Bitmap, LMask, 0);
end;