Hi Dale,
So Pixy only uses hue and saturation to find objects (not brightness), so Pixy is automatically fairly decent at dealing with different lighting and exposure changes (like what you describe). But still, lighting and exposure changes can affect the saturation, and things will break, like in your video. (Low light and low exposure results in lower saturation values.)
When Pixy creates a signature, it automatically calculates a range of saturations it expects based on the training set. When training on very uniform swatches (like you have in your video) Pixy will tend to create a fairly small saturation range. This needs to be improved…because it isn’t usually what’s wanted/needed.
But you can fix this by playing with the “Min saturation” and “Saturation spread” parameters. In particular, try increasing “Saturation spread” – it’s a multiplier, try 10.0 and see if that improves things. You might also try lowering “Min saturation”… bear in mind that these parameters only affect signature generation, so change the values and re-teach.
This link contains similar info, perhaps goes into a little more detail:
http://cmucam.org/projects/cmucam5/wiki/Some_Tips_on_Generating_Color_Signatures
