Recent development in the image sensing field has resulted in image sensors that feature security and machine vision applications, including gesture sensing, depth analysis, iris detection, eye tracking, night or low light vision, etc. In one aspect, these image sensors use traditional, VIS spectrum image sensing pixels to produce VIS images. In another aspect, these sensors also use additional, IR spectrum pixels to produce IR images. Basically, these sensors serve a dual purpose of producing both VIS and IR images.
Conventionally, such a dual purpose image sensor employs a direct combination design wherein an IR sub-sensor is physically juxtaposed next to a VIS sub-sensor. The VIS sub-sensor only includes VIS imaging pixels, and the IR sub-sensor only includes IR imaging pixels. This design offers simplicity, but the VIS and IR sub-sensors inevitably have different vantage points with regard to an imaging target. As a result, the resulting VIS and IR images not only have different optical spectra (VIS versus IR), but are also not able to be completely superimposed onto each other. This creates difficulties for subsequent image processing.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.