Solving camera bad feedback(several shades of horizontal lines moving up and down)

问题

It's bit difficult to define my problem as I am not sure the name of the symptoms, and its difficult to see it through static images. However I am still going to illustrate it, hope you all will get the idea of the problem.

Real time video with the horizontal shades video, very obvious, but cannot be seen through images. But view the next 2 images:

slightly more obvious here(through abs diff of background(a fixed static image) and current video streaming), though you have to squint your eyes to see it:

Kind of more obvious here(through thresholding the image. The white shades are moving up and down in the image):

Ok, so I am not sure what is the name of this symptom, I wish to know, what is this? What is the cause of this? And how can I solved it.

THings I have tried:

• increasing and decreasing exposure

• increasing and decreasing resolution

• use waitkey(), to lower the refresh rate

• increasing and decreasing frame per second.

Does anybody have any idea?

回答1:

AC lights (in the US) flicker on and off at a rate of 60 hertz, or 60 times per second. It is possible that you are getting the dark and light bands on the image because of this flickering matching up with the camera rate. This is what the effect can look like:

While LED lamps are known to do this, florescent lamps can also exhibit this effect in a lesser way. To eliminate this issue, it is recommended to change the camera to PAL or NTSC mode.

A good way to test out this issue would be to take the camera outside and try using it. Last time I checked, the sun does not flicker at 60 hertz. :) If the bands persist, then there is another issue going on.

回答2:

see if your ISO is on auto or not. if not, make sure it is and it should be fine.

回答3:

I was having the same issue on my c22 pro stream webcam. After reading the above response about the lights flickering at a certain rate, I do have ceiling flourescent lights in the room I am filming, I thought maybe disrupting the lights flickering timing might fix it. On a hunch I turned off the lights and then after a couple seconds turned them back on. Problem solved.

来源：https://stackoverflow.com/questions/22432652/solving-camera-bad-feedbackseveral-shades-of-horizontal-lines-moving-up-and-dow