Graphics::TBitmap *bmpOriginal = new Graphics::TBitmap();
bmpOriginal->Assign(Picture->Bitmap);
Graphics::TBitmap *bmpCopy = new Graphics::TBitmap();
bmpCopy->Width  = bmpOriginal->Height;
bmpCopy->Height = bmpOriginal->Width;

int wOr = bmpOriginal->Width, hOr = bmpOriginal->Height;
for(int x = 0; x < wOr; x++)
     for(int y = 0; y < hOr; y++)
          bmpCopy->Canvas->Pixels[hOr - y][x] = bmpOriginal->Canvas->Pixels[x][y];

Picture->Assign(bmpCopy);