1. A barcode reading system for a mobile device, the mobile device comprising a processor, a memory, a camera comprising a color image capture system including an image sensor array for generating a color image of a target area, and a white light source for generating illumination encompassing a first band of illumination, a second band of illumination, and a third band of illumination, wherein the color image comprises a first sub-image captured with a portion of the image sensor array sensitive to the first band of illumination, a second sub-image captured with a portion of the image sensor array sensitive to the second band of illumination, and a third sub-image captured with a portion of the image sensor array sensitive to the third band of illumination, the barcode reading system comprising: a barcode reading accessory including an optic system positioned within a field of illumination of the white light source when the barcode reading accessory is secured to the mobile device, the optic system comprising: an optical filter for passing a fourth band of illumination generated by the white light source, wherein one of a first portion of the image sensor array, a second portion of the image sensor array, and a third portion of the image sensor array are more sensitive to the fourth band of illumination than the other two portions; and a collimating optic for narrowing the field of illumination of the white light source to produce a targeting illumination pattern of the fourth band of illumination passed by the optical filter within the target area; and a barcode reading application stored in the memory and executable by the processor, the barcode reading application including: an image capture function for controlling the white light source and the camera to simultaneously capture the color image of the target area illuminated by illumination generated by the white light source and filtered by the optical filter; an image processing function for creating a grayscale composite image of the barcode within the target area by combining each of the first sub-image, the second sub-image, and the third sub-image using weights, wherein a contribution from a sub-image captured by a portion of the image sensor array most sensitive to the fourth band of illumination is smaller than a contribution from the other two sub-images captured by the other two portions of the image sensor array; a decoder function for receiving the grayscale composite image of the barcode and generating decoded data representing data encoded in the barcode; and a relay function for sending the decoded data to a remote server via a wireless connection established between the mobile device and a network.