Methods and systems are described for hair transplantation and other surgical procedures on a body surface. Specifically, methods and systems for computer-implemented and/or robotic hair transplantation and other surgical procedures, using time constrained image processing techniques are described. In various examples, multiple images of a body surface may be divided into overlapping sub regions for comparison. In various other cases, a percentage of an image of a body surface to be processed may be adjusted based on a time constraint. In some implementations, the output of one of these methods may be used as input for the other method.