Preview ignores colour matrix etc.

[Former user]

As I understand it, when a clip is converted from one set of primaries/transfer/matrix to another it should look the same in the preview window; after all the picture didn’t actually change, only its encoded bit representation. However, if I convert to linear RGB the picture in the preview is markedly darker.

I have attached a VapourSynth test script which shows this behaviour.

I’m using VapourSynth Editor r18, self-compiled on Gentoo.

Actually, I’m not quite sure if this is a bug in VapourSynth Editor, in VapourSynth/zimg, or in my head as I am just beginning to understand the basics of colour theory.

[Aleksey Lyashin]

To create the preview vsedit uses internal Resize filter, which uses zimg. The filter is set up so it reads matrix/transfer/primaries from the clip if they're present, or uses preview settings if they're not. So, when you convert the clip - preview is supposed to look different.