A method of determining a quantization value of the deviation of the average value of a distribution of severity difference between an initial time and a time after the initial time, the contrast-dependent severity between areas receiving a treatment and areas receiving a vehicle, comprising steps in which: at least one patient, at an initial time and at at least one time subsequent to the initial time, acquires at least one hyper-spectral image comprising at least one at least one of a sick area receiving the treatment, a healthy area receiving the treatment, a sick area receiving the vehicle and a healthy area receiving the vehicle, a weighting coefficient of each wavelength is determined, an optimized value is determined the value of the severity difference according to acquired hyper-spectral images including weighted wavelengths, for each patient and for each measuring time, and determining a quantization value of the deviation of the mean value between a distribution of the severity difference at the initial time and a distribution of the severity difference at a time subsequent to the initial moment according to the optimized values of the severity difference value for each patient at the initial time and the posterior moment.Procédé de détermination d'une valeur de quantification de la déviation de la valeur moyenne d'une distribution de l'écart de sévérité entre un instant initial et un instant postérieur à l'instant initial, la sévérité dépendant du contraste entre des zones recevant un traitement et des zones recevant un véhicule, comprenant des étapes au cours desquelles : on acquiert, pour au moins un patient, à un instant initial et à au moins un instant postérieur à l'instant initial, au moins une image hyper-spectrale comprenant au moins une zone parmi une zone malade recevant le traitement, une zone saine recevant le traitement, une zone malade recevant le véhicule et une zone saine recevant le véhicule, on détermine un coefficient de pondération de
