Aliasing after downsampling [duplicate]

1. Does downsampling cause aliasing?
2. How do you prevent aliasing in downsampling?
3. What happens when Downsample?
4. What causes aliasing?

Does downsampling cause aliasing?

If a discrete-time signal's baseband spectral support is not limited to an interval of width 2 π / M radians, downsampling by M results in aliasing. Aliasing is the distortion that occurs when overlapping copies of the signal's spectrum are added together.

How do you prevent aliasing in downsampling?

(b) Aliasing can be mitigated by integrating a low pass filter before the downsampling. The low-pass filter attenuate high-frequency band and thus inhibits high-frequency band aliasing.

What happens when Downsample?

Downsampling is done to decrease the bit rate when transmitting over a limited bandwidth or to convert to a more limited audio format. Contrast with upsample. See sampling. (2) To decrease the color depth of a digital image; for example, from 24 bits to 16 bits per pixel.

What causes aliasing?

Aliasing is the effect of new frequencies appearing in the sampled signal after reconstruction, that were not present in the original signal. It is caused by too low sample rate for sampling a particular signal or too high frequencies present in the signal for a particular sample rate.