Thanks for the follow. Good to see the difference between black and red plate characters. I am going to stick with my guess that it's the lower luminosity contrast for the red characters. Anyone have any other ideas?
(1) For license plate color issue: Can you see plates with black characters? Can you share a picture of them?
My theory of why red is likely to be more of a problem is that the luminosity contrast is lower for red on white than for black on white (here's an online ratio analyzer tool). Black on white scores the max 21. Red on white scores a far more modest 4:1 (you need to enter hex codes for each color - here's a directory of them).
It's likely harder to 'see' red on white than black on white.
(2) Thanks for sharing the Nanolux video. I couldn't find any significant new developments in the 2 years following that video's release. I did find Nanonlux's website that does look to be actively maintained.
That said, the demonstration in the video is really not that impressive. Here's a screencap of what they claim for color with no light:
If anyone knows more about Nanolux, I'd be interested to hear.
1. It's using IR illuminator at night, but it's color. Does it mean the camera remove IR cut filter and use FW to keep color, not B/W.
2 For the case to use IR illuminator at night, is it possible to see license plate with red characters? Please check below image, it shows it cannot see plate information that with red characters. Any comments here?
Color can be important for police departments in a state, local or municipal settings or a public safety department at a university. For example, having a color image of a potential suspect or suspect vehicle adds significant value when compared to only having a B/W image. It is also helpful when a victim of a crime describes the clothing or vehicle color and the investigator is able to review archived video to locate the suspect or suspect vehicle on another part of the campus/city.
If you need to detect color at night, you'll need to add white light illumination and keep in color mode. The same manufacturers of IR illuminators typically make white light units. See our test of white light illuminators.
I have often felt the need for colour under low light conditions, specially when there is a need to positively identify trouble makers in dimly lit crowded bars and similar scenarios. So perhaps one could say that while it is desirable most of the time, it becomes essential only about 10% of the time.