What is optical filter?
If you know Chinese character, you can reference the website as below.
http://bbs.cpsmedia.cn/frame.php?frameon=yes&referer=http://bbs.cpsmedia.cn/
Depending on that article, he inform me that Optical filter will improve two points
1. Infrared
2. Adjust the high frequency video image. (My English is not very good. So I do not use the “correct “ word to describe )
Some one asks me if we can use digital video Algorithm to replace optical filter?
I haven’t seen the Algorithm so far, especially adjust the Infrared
1. Infrared
In security or surveillance field, we want to cut infrared in daytime but we must need infrared in the night.
In daytime, we want to cut infrared because of beautiful picture.
We can see the comparison table as below.
The left picture is without IR cut filter. (that means the infrared will input the sensor )
The right picture is with IR Cut filter.
But in the night, we need capture the video by using extra infrared light source.
That is why we often hear Day & Night camera in the market.
The D&N camera has a switch IR cut filter machine controlled by motor. In daytime, the IR cut filter will auto be “with” IR cutl filter.
In the evening, the IR cut filter will auto be “without” IR cut filter.
If you have ability to let left picture to become right picture by using video Algorithm.
Be careful we will become rich guy.
2.Adjust the high frequency video image.
When I first to touch optical low pass filter (OLPF), I also think this thing is like stock’s moving average line (MA).
Compare with 1day MA and 10day MA, 10 day MA will be smoother than 1 MA.
That is trade off for detail information and trend (average).
The OLPF is like this. It will cut off Moiré (false color). But sometime it will loss a little resolution.
But the Day & Night camera will separate two parts, IR cut filter and OLPF.
Regarding IR cut filter, it will be controlled by CPU through Light Dependent Resistor signal.
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