Some people will understand those concepts better with examples:
Imagine you are in the Sahara desert at night with no lights out there in new moon. You fire a candle so you can see. Your vision adapts to the candle illumination that is 1 lumen. Let's call it one unit of illumination.
You can see things around. That is your sensibility is capable of seeing things in very dark conditions. Your sensibility is very high.
Now imagine that you are in a room at night, the illumination could be thousands of times bigger than with the candle, so your vision sensibility must be thousands of times smaller.
No you get out outside in Sahara desert at 12 AM in July and the illumination is millions or hundreds of millions of times stronger than with the candle. Your vision's sensibility must be hundreds of millions of times smaller.
Our senses adapt dynamically to the signal level. That is sensibility becomes inversely proportional to the signal level itself, starting from a given threshold of minimal signal we could perceive.
In a high dynamic range(a big range in illumination or sound levels) we can use logarithms to model that behavior. In a low dynamic range, we can use gamma or ulaw(in sound).
Imagine you are in the Sahara desert at night with no lights out there in new moon. You fire a candle so you can see. Your vision adapts to the candle illumination that is 1 lumen. Let's call it one unit of illumination.
You can see things around. That is your sensibility is capable of seeing things in very dark conditions. Your sensibility is very high.
Now imagine that you are in a room at night, the illumination could be thousands of times bigger than with the candle, so your vision sensibility must be thousands of times smaller.
No you get out outside in Sahara desert at 12 AM in July and the illumination is millions or hundreds of millions of times stronger than with the candle. Your vision's sensibility must be hundreds of millions of times smaller.
Our senses adapt dynamically to the signal level. That is sensibility becomes inversely proportional to the signal level itself, starting from a given threshold of minimal signal we could perceive.
In a high dynamic range(a big range in illumination or sound levels) we can use logarithms to model that behavior. In a low dynamic range, we can use gamma or ulaw(in sound).