Allow scanning codes that are color inverted

[jiapw]

I used inverted luminance for all even frames to handle the case that the code being scanned is color inverted. For production, that should be made as an option, sorry I didn't walk through the entire library to learn how to do it.

P.S. I duplicated the loop for converting pixels, because I think that hurts performance a bit if the odd-even branching is made for every pixel. Not sure of that, I am not a TS guy. :) This is the first time for me to write TS code.

[werthdavid]

That's nice! Have you tested that?

[johnnyb]

What is the status of this? This would be extremely helpful for my current project.

[werthdavid]

Can somebody test this and confirm that it works correctly?