Illustration of the annulus-wise PCA post-processing and merit function evaluation used in the negative fake companion technique. Left: no NEGFC was injected before annulus-wise PCA processing. Right: a NEGFC was injected at the position and flux minimizing the merit function. The white circle illustrates the fixed circular aperture from which the pixel values I_j have been extracted to evaluate the merit function. The same color-scale was used for both images.