Gets the raw samples at the image's own resolution, Stride × Height bytes in the §8.9.3 layout.
public ReadOnlySpan<byte> Samples { get; }
ISO 32000-2 §8.9.3. Rows the data did not reach are zero. For an image kept encoded this decodes it at its full resolution (GetSamplesAt(Int32) with 0); empty when it cannot be decoded.