1. A method of using image processing to automatically identify and complete a fill-in field of a printed form document, the method comprising: by an electronic device having a processing device, executing programming instructions that cause the processing device to: receive an image file of a printed form having at least one fill-in field that contains a handwritten symbol within a field boundary, process the image file using a computer-implemented image processing function to automatically identify a fill-in field on the printed form and the handwritten symbol that is contained within the identified fill-in field, by a communication hardware component of the electronic device: communicatively connect to a proximate user mobile device, and access a data file from the proximate user mobile device, wherein the data file comprises a plurality of categories and stored values, retrieve a candidate value that corresponds to the identified handwritten symbol by: identifying, from the data file, a category that corresponds to the handwritten symbol, extracting the stored value for the identified category from the data file, and using the extracted stored value as the candidate value, insert the candidate value in the identified fill-in field, and cause a document generation device to generate a document comprising the form with the selected candidate value displayed in the identified fill-in field.