How to extract frames from a video?

Question

Video processing

To do this, you need to divide the recorded video into frames, but so that there are no blurry frames, or automatically remove blurry frames.
1. What causes blurry frames?
2. Perhaps you can use some kind of high-quality camera so that they are not? Because from the camera phone they are. If so, which one?
3. Is it possible to identify blurry frames and throw them away? I think not in general.

Answer 1

1. Long exposure of each frame.
2. Lots of light, sensitive matrix, 60fps or more. Some cameras allow you to manually set the shutter speed for each frame.
3. You can. For each frame, the value of the amount of information (clarity) is calculated. This is frequency analysis in one form or another - the more energy is concentrated in the high-frequency part of the spectrum, the sharper the image. You can find various approaches to calculating this value on the net. Next, select a time interval, for example 1 second, look at which frame in this interval has the highest clarity value and select it accordingly. At the same time, you choose some threshold value to detect the case when the entire time interval consists of blurry frames.

Answer 2

1.2. In any case, footage from a moving video camera will be a little blurry, so it's best to stop for a while. To shoot panoramas, some people simply use several high-quality cameras aimed in different directions and taking a picture at the same time - this way it is less likely that objects will move during the shooting and it will not be possible to sew the ends together (or "ghosts" will appear).
About extracts. HDR is used to create a professional panorama , i.e. shooting the same frame several times with different exposure values, as the lighting can be very uneven.
3. To find the clearest frames, you can apply the autofocus algorithm (frequency descriptors, as @Lerg wrote ).