1. A dual-spectrum digital imaging arc welding system providing enhanced discrimination between arc welding characteristics to a user, said system comprising: a welding headgear configured to be worn on a head of a user and to shield at least the eyes of said user from spectral radiation emitted by an arc welding process; a visible-spectrum digital camera physically integrated with said welding headgear and configured to provide raw visible spectrum real-time digital video image frames; an infrared-spectrum digital camera physically integrated with said welding headgear and configured to provide raw infrared-spectrum real-time digital video image frames; an optical display assembly physically integrated with said welding headgear and configured to present real-time digital video images to said user while said user is wearing said welding headgear; a vision engine integrated with said welding headgear and operatively interfacing with said visible spectrum digital camera, said infrared-spectrum digital camera, and said optical display assembly, wherein said vision engine is configured to spatially align and temporally correlate at least said raw visible spectrum and raw infrared-spectrum real-time digital video image frames producing at least dual-spectrum real-time digital video image frames from said raw visible spectrum and raw infrared-spectrum real-time digital video image frames; and a user interface integrated with said welding headgear and operatively interfacing to at least one of said vision engine and said optical display assembly and configured to allow a user to manually select an imaging mode from a plurality of selectable and pre-defined imaging modes, wherein the plurality of selectable and pre-defined imaging modes include displaying infrared-spectrum information in a first portion of said optical display assembly associated with one of a welding arc and a weld puddle, and displaying visible spectrum information in a second portion of said optical display assembly associated with the other of the welding arc and the weld puddle.