FIG. 6 illustrates an example of how a change alert image generated by the change alerting system may appear. In FIG. 6, the larger image is the change image, shown in a divergent red-white-green color scheme, where red tones indicate negative change, green tones indicate positive change, and white tones indicate neutral areas with minimal change. Overlaid on the change image are the regions of significant change, shown as a blue outline. The smaller images show the normalized VI layers for the master and companion images. These images use a red-yellow-green color scheme, with below-average VI values shown as red tones, VI values close to average shown as yellow tones, and above-average VI values shown as green tones.

Example Computer System

FIG. 7 is a block diagram illustrating components of an example machine for reading and executing instructions from a machine-readable medium. Specifically, FIG. 7 shows a diagrammatic representation of network system 120 and client device 130 in the example form of a computer system 700. Thus, the computer system implements the method 300 of FIG. 3. The computer system 700 can be used to execute instructions 724 (e.g., program code or software) for causing the machine to perform any one or more of the methodologies (or processes) described herein. In alternative embodiments, the machine operates as a standalone device or a connected (e.g., networked) device that connects to other machines. In a networked deployment, the machine may operate in the capacity of a server machine or a client machine in a server-client system environment 100, or as a peer machine in a peer-to-peer (or distributed) system environment 100.