Image markers are a type of on-screen analysis that allows the thermographer to pin-point a specific spot on an object within an image. Markers will also include the temperature reading at the marked point.
Markers provide two main benefits: first they are useful for highlighting a location for someone viewing the thermal image and secondly they can be used as reminders for the thermographer when creating reports using the computer software.
Some cameras allow for marking both thermal and visual images, some allow marketing thermal images only. In addition, higher end cameras will usually support the addition of multiple image markers, whereas entry or mid-level cameras with either not offer this capability or will only support a limited number of markers.