Method and device for processing images in order to automatically estimate the position of a trocar

An image processing method for processing endoscopic images for the automatic estimation of the position of at least one trocar (58), each trocar (58) being configured to permit the passage of a substantially straight instrument (54) therethrough, characterized in that it comprises:

• a step (110) of receiving at least two images (118a, 118b), each of the images being an endoscopic image showing at least one instrument (54) passing through each trocar (58), said instrument being in a different orientation and/or position in at least two of the images (118a, 118b),
• a step (130) of determining, from the images and in at least said two images, the position and the orientation of each instrument (54) with respect to a reference position,
• a step (160) of estimating, from the images, the position of each trocar (58) with respect to the reference position, from at least two positions and orientations of the instrument (54) passing through this trocar (58), comprising, for each trocar:
• a sub-step (160a) of defining a main axis (60a, 60b) of the instrument (54) passing through the trocar (58),
• a sub-step (160b) of determining, from each image, a group of main axes of the instrument in each position and orientation of the instrument,
• a sub-step (160c) of determining the intersection (62) of the main axes of the group in each position and orientation of the instrument,
• a sub-step (160d) of estimating the position of the trocar (58) by matching said position with the intersection (62) of the main axes corresponding to the instrument (54) passing through said trocar (58).