1. A method for adaptively varying resolutions of captured images, the method being performed by a graphical code reader, the method comprising: capturing images; and varying the resolutions at which the images are captured based on brightness information that is determined about the captured images; wherein varying the resolutions at which the images are captured based on the brightness information comprises decreasing the number of pixels that are included in a next captured image relative to the number of pixels that were included in a most recently captured image if the brightness of the most recently captured image exceeds an upper threshold; and wherein varying the resolutions at which the images are captured based on the brightness information also comprises increasing the number of pixels that are included in the next captured image relative to the number of pixels that were included in the most recently captured image if the brightness of the most recently captured image is less than a lower threshold.