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function Thumbnail(InStream: TStream;Width, Height: Integer; FillColor: TColor=clWhite):TBitmap;
var
  JpegImage: TJpegImage;
  Bitmap: TBitmap;
  Ratio: Double;
  ARect: TRect;
  AHeight, AHeightOffset: Integer;
  AWidth, AWidthOffset: Integer;
begin
//  Check for invalid parameters
  if Width<1 then
    raise Exception.Create('Invalid Width');
  if Height<1 then
    raise Exception.Create('Invalid Height');
  JpegImage:=TJpegImage.Create;
  try
//  Load the image
    JpegImage.LoadFromStream(InStream);
// Create bitmap, and calculate parameters
    Bitmap:=TBitmap.Create;
    try
      Ratio:=JpegImage.Width/JpegImage.Height;
      if Ratio>1 then
      begin
        AHeight:=Round(Width/Ratio);
        AHeightOffset:=(Height-AHeight) div 2;
        AWidth:=Width;
        AWidthOffset:=0;
      end
      else
      begin
        AWidth:=Round(Height*Ratio);
        AWidthOffset:=(Width-AWidth) div 2;
        AHeight:=Height;
        AHeightOffset:=0;
      end;
      Bitmap.Width:=Width;
      Bitmap.Height:=Height;
      Bitmap.Canvas.Brush.Color:=FillColor;
      Bitmap.Canvas.FillRect(Rect(0,0,Width,Height));
// StretchDraw original image
      ARect:=Rect(AWidthOffset,AHeightOffset,AWidth+AWidthOffset,AHeight+AHeightOffset);
      Bitmap.Canvas.StretchDraw(ARect,JpegImage);
// Assign back to the Jpeg, and save to the file
        Result := Bitmap;
finally
end;
finally
end;

end;