1. A method comprising: detecting a burn-in event that causes thermal images captured by a focal plane array (FPA) to exhibit a blemish, wherein the detecting comprises: performing a first flat field correction (FFC) process to determine first FFC terms, performing a second FFC process to determine second FFC terms, comparing the first and second FFC terms, identifying, based on the comparing, corresponding ones of the first and second FFC terms that exhibit differences greater than a threshold amount, identifying one or more pixels corresponding to the identified first and second FFC terms, and associating the identified pixels with the burn-in event; and mitigating the blemish in the thermal images.