The lower limit of an accurate determination of stellar brightness is usually determined from the standard deviation of a certain part of the star deflection, as it is recorded by the recording facility at hand. This sample is considered, according to the observer’s estimation (judgment) to reflect the noise of his photometric system and is clear from any real stellar brightness variations. The combined use of Fractal analysis, Fourier analysis and wavelet analysis will improve efficiently the ability of the available instrumentation in detecting weak transient stellar brightness variations. Fractal analysis will provide decisive arguments on the estimation of the sample randomness and will indicate the presence or not of non-random constituent in the sample and Fourier and wavelet analysis will provide the exact determination of this variation in the frequency and in the time domain.