Determination of the dip amplitude with the example of HP Tau. Top: light-curve detrending of the original data (black) with a boxcar of size 4 ⋅ P. The blue line is the trend. Bottom: detrended light curve. The convolution with a boxcar removes a small part of the data at the edges. Orange line: flux median. Red lines: 90th and fifth percentiles of flux. The usage of flux percentiles allows us to consider the global variability of the light curve.