The noise, measured in db (decibels), quantifies the Signal to Noise Ratio, i.e. the amount of signal as a function of the amount of noise. In this way, the higher the SNR, the greater the signal, which implies the absence of noise. Characteristically, any SNR graph taken on a tonal or densitometric scale will present less noise towards the high lights, and more noise towards the shadows. The lack of coherence in this evolution can inform us of noise reduction processes during image processing or defects in the signal processing of our equipment.
SNR information is shown through the following panels:
- SNR-RGB: shows the SNR for each R, G and B channel, so that it is possible to evaluate which channel has the best signal-to-noise ratio and the coherence in its evolution. For example, neutrality adjustment processes (white balance) can induce more noise in some channels than others, due to the lack of signal.
- SNR: shows the SNR along the luma.
- RDEV: shows the dynamic range of the scene studied in terms of EV.
- Avg Dev: it is shown only for SNR-RGB and it shows the average deviation along each sample in relation to the difference between its channels.
- Max and Min deviation: it is shown only for SNR-RGB and it indicates the maximum and minimum deviation along the channels and samples.
- Average: it indicates the average SNR
- Dev: indicates the standard deviation
- Max and Min the maximum and minimum SNR peaks.