将bmp文件转换为jpg文件

procedure TForm1.Button1Click(Sender: TObject);
(*压缩MBP为JPEG;但是没有提供压缩比可选项
凑合用吧，大概1/3 ^_^:
Note:必须加上JPEG到Uses单元
*)
var
MyJPEG : TJPEGImage;
MyBMP : TBitmap;
begin
MyBMP := TBitmap.Create;
with MyBMP do
try
LoadFromFile('e:lm.BMP'); //你的图片位置
MyJPEG := TJPEGImage.Create;
with MyJPEG do begin
Assign(MyBMP);
CompressionQuality:=10; //压缩比例
Compress;
SaveToFile('e:lm01.JPEG');//保存路径……
Free;
end;
finally
Free;
end;
end;

---

By Luiz Vaz - luiz.vaz@arinso.com.br

function Bmp2Jpg(Bmp: TBitmap; Quality: Integer = 100): TJpegImage;

begin

  Result := nil;

  if Assigned(Bmp)

  then begin

  Result := TJpegImage.Create;

  Result.Assign(Bmp); {Its all folks...}

  Result.CompressionQuality := Quality;

  Result.JPEGNeeded; {Key method...}

  Result.Compress;

  end;

end;

function Jpg2Bmp(Jpg: TJpegImage): TBitmap;

begin

  Result := nil;

  if Assigned(Jpg)

  then begin

  Result := TBitmap.Create;

  Jpg.DIBNeeded; {Key method...}

  Result.Assign(Jpg); {Its all folks...}

  end;

end;

注意：JPEGNeeded过程转换并存储图像数据到内部的JPEG数据。我们无法直接存取JPEG 内部数据，因为D5并没有提供jpeg.pas单元的源码。但是可以通过JPEGNeeded和DIBNeeded过程来操作它。