Automatic exposure module for an image acquisition system

A method for automatically determining exposure settings for an image acquisition system, the image acquisition system comprising an infra-red (IR) illumination source and an image sensor responsive to selected IR wavelengths, the method comprising:

• acquiring an image of a subject from a camera module while the subject is illuminated by the IR illumination source;
• determining a light condition occurring during the acquisition based on the acquired image of the subject, including detecting at least one feature of the subject in the acquired image and determining the lighting condition based on a region of the acquired image corresponding to the detected at least one feature;
• determining a distance between the subject and the camera module during the acquisition based on the acquired image of the subject;
• determining whether to make a correction of the image exposure settings for the camera module based on the determined distance and the determined light condition;
• and
• responsive to determining to make the correction of the image exposure settings for the camera module:
• determining image exposure settings corresponding to the determined distance and to the determined light condition;
• and
• acquiring a new image of the subject using the determined image exposure settings.

An acquisition system comprising:

• an infra-red (IR) illumination source;
• an image sensor responsive to selected IR wavelengths;
• and
• image processing means arranged for executing the operations of claim 1.

A system for automatically determining exposure settings for an image acquisition system, wherein the image acquisition system comprises an infra-red (IR) illumination source and an image sensor responsive to selected IR wavelengths, the system comprising a processor executing instructions to:

• acquire an image of a subject from a camera module while the subject is illuminated by the IR illumination source;
• determine a light condition occurring during the acquisition based on the acquired image of the subject, including detecting at least one feature of the subject in the acquired image and determining the lighting condition based on a region of the acquired image corresponding to the detected at least one feature;
• determine a distance between the subject and the camera module during the acquisition based on the acquired image of the subject;
• determine whether to make a correction of the image exposure settings for the camera module based on the determined distance and the determined light condition;
• responsive to determining to make the correction of the image exposure settings for the camera module:
• determining image exposure settings corresponding to the determined distance and to the determined light condition;
• and
• acquiring a new image of the subject using the determined image exposure settings.