Chroma threshold considerations

[Novakasa]

Increasing the chroma threshold is definitely experimental. Mostly for my own reference, here is some old measurement data:
RGB:

Chroma value (unfortunately the axis labels are black so doesn't show well on github dark mode):

So this is a blue, green, red and blue marker (in that order).

It seems the lowest chroma value is the green, where chroma is approximately 4200.
Then comes Blue with 5900, then red with 7200.

Depending on what marker colors the layout actually uses, you want to make sure that the chroma threshold is at least ~500 below the actual chroma value of your markers. This is why I chose 3500 as the default threshold, it still will reliably trigger on a green marker. If you don't have any green markers in the layout, 5000 should be safe.

Increasing the chroma threshold should also only be necessary, if there are some colors on the track that have high chroma values and have similar hues to the actually used markers. For example, the color brown might be seen as a red marker, if the chroma threshold is too low. If there are colors on the track that have different hues than actually used markers (e.g. green baseplates, but no green marker used, brickrail should be smart enough to not trigger a marker on the green baseplates, even if the chroma threshold is low enough for the green baseplates. This only works of no green marker is used in the layout though, and at least one marker does not have the color None.