unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls,    
  Forms, Dialogs,jpeg, ExtCtrls, StdCtrls,ActiveX, AxCtrls;
type
  TForm1 = class(TForm)
    Image1: TImage;
    Button2: TButton;
    Image2: TImage;
    procedure Button2Click(Sender: TObject);
  private
    procedure StreamToVariant(Stream: TMemoryStream;
                              var v:  OleVariant);
    procedure VariantToStream(const v: olevariant;
                              Stream: TMemoryStream);
    procedure JPEGToVariant(aJPEG : TJPEGImage;
                             var aVariant:OleVariant);
    procedure VariantToJPEG(aValue : OleVariant;
                             var aJPEG:TJPEGImage);
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.VariantToStream (const v : olevariant; Stream : TMemoryStream);
var
  p : pointer;
begin
  Stream.Position := 0;
  Stream.Size := VarArrayHighBound (v, 1) - VarArrayLowBound (v, 1) + 1;
  p := VarArrayLock (v);
  Stream.Write (p^, Stream.Size);
  VarArrayUnlock (v);
  Stream.Position := 0;
end;

procedure TForm1.StreamToVariant (Stream : TMemoryStream; var v : OleVariant);
var
  p : pointer;
begin
  v := VarArrayCreate ([0, Stream.Size - 1], varByte);
  p := VarArrayLock (v);
  Stream.Position := 0;
  Stream.Read (p^, Stream.Size);
  VarArrayUnlock (v);
end;

procedure TForm1.JPEGToVariant(aJPEG : TJPEGImage; var aVariant:OleVariant);
var
  Stream        : TMemoryStream;
begin
    try
      Stream := TMemoryStream.Create;

      aJPEG.Assign(Image1.Picture.Bitmap);
      aJPEG.SaveToStream(Stream);

      StreamToVariant(Stream, aVariant);
    finally
       Stream.Free;
   end;
end;

procedure TForm1.VariantToJPEG(aValue : OleVariant;var aJPEG:TJPEGImage);
var
   Stream : TMemoryStream;
begin
try
  Stream := TMemoryStream.Create;

  VariantToStream (aValue,Stream);
  aJPEG.LoadfromStream(Stream);

finally
   VariantClear(aValue);
   Stream.free;
end;
end;

procedure TForm1.Button2Click(Sender: TObject);
var
   aJPEG :TJPEGImage;
   aVariant : OleVariant;
begin
try
   aJPEG:=TJPEGImage.Create;

   //JPEG To Variant
   aJPEG.Assign(Image1.Picture.Bitmap);
   JPEGToVariant(aJPEG,aVariant);

   //Variant To JPEG
   VariantToJPEG(aVariant,aJPEG);
   Image2.Picture.assign(aJPEG);
finally
   aJPEG.free;
end;
end;

end.