Consumers can buy attachments that add thermal-imaging capability to smartphones. Jon Keegan in the Wall Street Journal reviews two such attachments: the Flir One and the Seek Compact, which he tried out on his iPhone 5S.

He notes two main differences: the Seek Compact is powered by the phone—a simple scheme that unfortunately takes “…a serious toll on your phone’s battery.”

The other difference, he says, is that the Flir One has a traditional as well as thermal camera, yielding a composite image in which the full-color camera provides high-contrast edges to the thermal blobs—helpful, Keegan writes, “..when you go back to look at your images later. In many cases, you’d otherwise have no clue what you’re looking at.”

Keegan concludes that the Flir One will be the better choice for most people, while the Seek Comact, with its larger sensor and wider thermal detection range (-40 to +626°F, vs -4 to +248°F for the Flir One) can be the better pick for technical applications.

The Flir One employs Flir’s smaller-than-a-dime Lepton longwave infrared (LWIR) camera, which you can use to integrate thermal imaging into products of your own design. Lepton is available through distributors such as Digi-Key, as previously reported.