[ecfisa]

Hola jusar.

Usando bitmap podés hacer:

bool IsBitmapsEqual(Graphics::TBitmap* B1, Graphics::TBitmap* B2)
{
  if( B1->Height != B2->Height || B1->Width != B2->Width ||
      B1->PixelFormat != B2->PixelFormat )
    return false;
  for(int i =0; i < B1->Height ; i++ )
    if(memcmp(B1->ScanLine[i],
      B2->ScanLine[i],B1->Width * (B1->PixelFormat) / 8) != 0)
      return false;
 return true;
}

Ejemplo llamada:

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  ShowMessage( IsBitmapsEqual(Image1->Picture->Bitmap,
    Image2->Picture->Bitmap ) ? "IGUALES" : "DIFERENTES" );
}

Saludos.