1. A method of generating, during acquisition via a camera of a foreground document, a plurality of pre-processed images of the foreground document, the pre-processed images being used to optimize a capture position of the camera when capturing the foreground document for optical character recognition, the method comprising: obtaining a plurality of source images, including a first source image and a second source image, continuously acquired via the camera of a computing device, each of the obtained plurality of source images containing characters associated with the foreground document, wherein the first source image is acquired by the camera at a first capture position, and wherein the second source image is acquired by the camera at a second capture position, wherein the first capture position is different from the second capture position; for each of the plurality of obtained source images, pre-processing a given obtained source image to generate, by a processor of the computing device, a pre-processed image of the given obtained source image so as to emphasize the characters associated with the foreground document and to attenuate image background objects that are background to the characters associated with the foreground document by i) detecting edges of the characters in the given obtained source image using an image processing operation, ii) thickening edges of the characters of the detected edge characters to generate a first intermediate image data using a second image processing operation, and iii) thresholding the first intermediate image data; and presenting, on a graphical user interface, via a display of the computing device, i) the pre-processed image and ii) a graphical indicator to guide physical repositioning of the camera to capture an image to be used by an optical character recognition operation to determine characters of the foreground document, wherein the graphical widget presents one or more parameters associated with repositioning of the camera relative to the foreground document, wherein the one or more parameters are determined based on the characters associated with the foreground document in the pre-processed image.