private void AssertEqual(ScratchImage image, Bitmap expected)
{
// Check various meta-data.
var metaData = image.GetMetadata();
AssertEqual(metaData, expected);
// Check raw contents match. (This test only works for specific images)
var img = image.GetImage(0);
var expectedBytes = expected.GetRawBytesRGBA();
var readBytes = new byte[expectedBytes.Length];
Marshal.Copy(img.Pixels, readBytes, 0, readBytes.Length);
Assert.That(readBytes, Is.EqualTo(expectedBytes));
}