Setting up the relative fluxes within a sequence of 70 images: 1) three sequences, covered by horizontal lines, are built around three reference images (black, blue, and brown arrows). Gain × fluxes ratios are determined as in Fig. 11 (I_cur = 9, I_ref = 11). 2) The reference image of sequence 2 is measured relative to reference 1 and reference 3 relative to reference 2. By transitivity all fluxes are related. 3) The two overlap regions 1 over 2 and 2 over 3 yield a set of double determinations. The relative fluxes of all 70 images agree within 3 × 10^-5 rms. They give the relations flux vs. exposure time (shaded area: 28 images at a common LED current) and flux vs. LED current (constant exposure time). The only significant LED jitter occurs between images 55 and 56.