Converts count colours of 8-bit samples, as an image row holds them, to 8-bit device colours.
public void Convert(ReadOnlySpan<byte> source, Span<byte> destination, int count)
At least count × InputCount samples. Each maps linearly from 0..255 onto its component's
range (the default Decode of Table 88), except in an Indexed space, where a sample is the index.
At least count × OutputCount bytes; receives the device colours, 0 to 255.
The number of colours.
ISO 32000-2 §8.9.5.2. One-component spaces convert through a table of 256 colours built once.