AUTO-EXPOSURE METHOD USING CONTINUOUS VIDEO FRAMES UNDER CONTROLLED ILLUMINATION

摘要

An illumination control process for use in a digital image capture and processing system includes illuminating an object in the field of view with different pulses of illumination over a pair of image frames, detecting digital images of the illuminated object over these image frames, and decode processing the digital images. In an embodiment, upon failure to read a symbol in one of the first and second images, these digital images are analyzed in real-time, and based on the results of this real-time image analysis, the exposure time is adjusted during subsequent image frames. In another embodiment, upon failure to read a symbol in one of the first and second images, these digital images are analyzed in real-time, and based on the results of this real-time image analysis, the energy level of the illumination is adjusted during subsequent image frames.

主权项

1. A method of controlling illumination processes within a digital image system having a field of view, comprising:
illuminating an object in the field of view at a first energy level; capturing a first digital image of the object illuminated at the first energy level using a predetermined exposure duration; attempting to read a symbol in the first digital image; if a symbol is not read in the first digital image, illuminating the object in the field of view at a second energy level that is different from the first energy level; capturing a second digital image of the object illuminated at the second energy level using the predetermined exposure duration; attempting to read a symbol in the second digital image; if a symbol is not read in the second digital image, analyzing the first digital image and the second digital image to measure whether:
the first digital image and the second digital image are both too dark;the first digital image and the second digital image are both too bright; orone of the first digital image and second digital image is too bright and the other of the first digital image and second digital image is too dark; determining a modified energy level based on the analysis of the first digital image and second digital image; determining a modified exposure duration based on the analysis of the first digital image and second digital image; illuminating the object in the field of view at the modified energy level; capturing a first subsequent digital image of the object illuminated at the modified energy level using the modified exposure duration; attempting to read a symbol in the first subsequent digital image; if a symbol is not read in the first subsequent digital image, illuminating the object in the field of view at the second energy level; capturing a second subsequent digital image of the object illuminated at the second energy level using the modified exposure duration; and attempting to read a symbol in the second subsequent digital image.