procedure GetResJpg(JPGFile: string);
 const
 BufferSize = 50;
 var
 Buffer: string;
 Index: integer;
 FileStream: TFileStream;
 HorzRes, VertRes: Word;
 DP: Byte;
 Measure: string;
 begin
 FileStream := TFileStream.Create(JPGFile,
 fmOpenReadWrite);
 try
 SetLength(Buffer, BufferSize);
 FileStream.Read(buffer[1], BufferSize);
 Index := Pos('JFIF' + #0$00,buffer);
 if Index > 0 then
 begin
 FileStream.Seek(Index + 6, soFromBeginning);
 FileStream.Read(DP, 1);
 case DP of
 1: Measure := 'DPI'; //Dots Per Inch 
 2: Measure := 'DPC'; //Dots Per Cm. 
 end;
 FileStream.Read(HorzRes, 2); // x axis 
 HorzRes := Swap(HorzRes);
 FileStream.Read(VertRes, 2); // y axis 
 VertRes := Swap(VertRes);
 end
 finally
 FileStream.Free;
 end;
 end;

 procedure SetResJpg(name: string; dpix, dpiy: Integer);
 const
 BufferSize = 50;
 DPI = 1; //inch 
 DPC = 2; //cm 
var
 Buffer: string;
 index: INTEGER;
 FileStream: TFileStream;
 xResolution: WORD;
 yResolution: WORD;
 _type: Byte;
 begin
 FileStream := TFileStream.Create(name,
 fmOpenReadWrite);
 try
 SetLength(Buffer, BufferSize);
 FileStream.Read(buffer[1], BufferSize);
 index := POS('JFIF' + #0$00,buffer);
 if index > 0
 then begin
 FileStream.Seek(index + 6, soFromBeginning);
 _type := DPI;
 FileStream.write(_type, 1);
 xresolution := swap(dpix);
 FileStream.write(xresolution, 2);
 yresolution := swap(dpiy);
 FileStream.write(yresolution, 2);
 end
 finally
 FileStream.Free;
 end;
 end;