Remarks on Colour line that 'There is no such thing as phenomenology, though there are phenomenological problems.' He was content to regard Goethe's observations as a kind of logic or geometry. Wittgenstein took his examples from the Runge letter included in the "Farbenlehre", e.g. "White is the lightest colour", "There cannot be a transparent white", "There cannot be a reddish green", and so on. The logical status of these propositions in Wittgenstein's investigation, including their relation to physics, was discussed in Jonathan Westphal's "Colour: a Philosophical Introduction" (1991). Although "Remarks on Colour" is considered difficult on account of its fragmentation, his last work,
Colour recovery frequency, known as the "colour subcarrier". Black and white televisions do not decode this extra colour information in the subcarrier, using only the luminance to provide a monochrome picture. However, due to limited bandwidth in the video channel, the chrominance and luminance signals bleed into each other considerably, resulting in the colour information showing up visibly as Chroma Crawl, or Chroma dots on black & white TV sets. This is normally considered a nuisance in analogue broadcasting. However, since telerecordings were made from black & white TV screens and technicians at the time often decided not to apply a filter