Hemorrhagic stroke is the leading cause of disability related to stroke, it is caused by the rupture of cerebral blood vessels. The rupture of the blood vessels pours the blood into the surrounding tissues causing the hematoma. In general, it is by simple visual reading of the brain CT scan image that the specialist must make a decision about the evolutionary stage and decide on the management. The present work aims to quantify the hyperacute and subacute stages of hemorrhagic stroke. We used a material consisted of haemorrhagic stroke CT scan images collected at Cotonou National University Hospital (CNHU-HKM) scanner unit. We also used MATLAB R2015a as processing environment. The proposed method is based on a priori knowledge of the hematoma, especially on its transformations during evolutionary stages. The method consisted in modeling by mathematical functions the distribution of oxyhemoglobins in the hematoma. On a sample of a database of 102 images, the method yielded a pass rate of 86.23%. This method of dating the hematoma will certainly be a decision-making tool in the diagnosis and management of haemorrhagic stroke.