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 cast Improper timing or imbalanced chemical mixtures can cause unwanted casts. Colour casts can also occur in old photographs due to fading of dyes, particularly under the action of ultra violet light. These may be correctable on a scanned version of the photograph with image editing techniques. Most digital cameras try to automatically detect and compensate colour cast and usually have a selection of manually set white balance settings to choose from. Otherwise, photo editing programs, such as Photoshop, often have built in colour correction facilities. For film, blue filters and amber filters are used to counter casts. Amber filters are