IR image of the day: coffee and chat

My wife, sat drinking coffee, and wearing a quilted jacket.

Infrared images featuring people are among the easiest to interpret, and inevitably some of the more interesting.

Here, my wife sits, her right elbow resting on the table in front of her, and her right hand resting against her jaw, a large Costa coffee cup in front of her. She is listening to a friend on the opposite side of the table, and wears a quilted jacket which is open at the front.

Behind and in front of her the wall and table are cool, it being a chilly autumn morning (the area is sheltered but not well heated).

Her face and hand are the warmest areas of the image, with skin temperatures typically around 33˚C. These are highest where subcutaneous fat is thinnest, around the mouth and on the forehead, where there is also a rich superficial blood supply. Her hair is cool, demonstrating its inherent insulation for the scalp. The glass in her spectacles appears (and probably is) quite cold, but as its reflectivity/emissivity is different from skin and other surfaces this must be interpreted with caution.

Her quilted jacket, a good insulator, also has a cool surface, although parts of it which are more compressed, around the left armpit for instance, are warmer and ‘letting the heat through’. The sewn compartments in the quilting are also shown quite clearly in places. Cheap sewn-through quilting would be much warmer along those lines, but this jacket uses better box-quilt construction for greater warmth. Where the jacket gapes at the front, her warmer clothing underneath is obvious.

The coffee cup is still warm from its contents, but is cooling from the top lip down. The Costa lettering on the cup appears to be colder, but this is likely to be an artefact, either from the reflectivity/emissivity of the paint used in that lettering, or from the superimposed MSX visual image.

My wife, sat drinking coffee, and wearing a quilted jacket.
My wife, sat drinking coffee, and wearing a quilted jacket.

Image captured using a FLIR One™ IR camera and iPhone 6. Standard ‘Iron’ palette, without further image processing.