Thanks Fraser
I think thermal imaging is presently roughly 30 years behind visible light cameras. About 25 years ago my employer needed a digital camera for taking location reference pictures in the field. Only two models were really available - one offering 320 x 240 and the other 640 x 480 pixels. That's visible, not thermal. We chose the higher resolution because, while all agreed that the photos from the 320 x 240 were just about good enough, the extra resolution was better. I think we paid something like £1000 for the camera, which may well have been a QV-10. Either way, the price of the camera was a
very small part of the whole project cost.
320 x 240 resolution is roughly the same as a NTSC VHS video tape. 384 x 288 (as per Therm-App et al) equates broadly to PAL VHS, while 640 x 480 is comparable to a DVD or mini-DV video recording. There definitely are 1024 x 768 uncooled sensors available out there on the civilian market, though they're rather expensive (FLIR has at least one range of that resolution, which starts at the price of a luxury car - and a full set of lenses can double that). I strongly suspect there are higher resolution uncooled LWIR sensors around, for military or at least experimental purposes. No-one's talking much about those, though.
Not all applications require the same aspect ratio: a scope might benefit from a square (or even round!) image, whereas a driving aid might find an extreme widescreen view more relevant (drivers generally don't need to see the clouds). Some relatively commonly available imagers are near-square (5:4, eg 640 x 512) as opposed to the 4:3 of more common types (320 x 240, 384 x 388, 640 x 480 etc).
I'm well aware that there are technical differences between the way thermal and visible light sensors presently work, and that the manufacture of thermal sensors is much harder (not to mention complex, needing a readout IC (ROIC) bonded directly to, and at least the same size as, the thermal sensor matrix). But my suspicion is that there may be a development around the corner with some hitherto-unknown thermally sensitive arrangement that simplifies - cheapens - the sensors. Lenses remain an issue, with nothing presently much better than germanium or zinc selenide, although the chalcogenide glasses may be catching up). Everything
after the sensor, in terms of image processing and display, is essentially the same as that used for visible light images. That part is only more expensive because relatively few are made and there are none of the huge economies of scale that you get in, say, phone cameras.
As I've said elsewhere, I look forward to the day we can all buy multi-megapixel thermal imaging cameras. High resolution thermal images can look good - see
here,
here,
here,
here,
here,
here,
here,
here,
here,
here,
here and
here for just a few examples of the state of the art in stitched hi-res thermal images. Some of these took quite a while to put together. Perhaps it's a pipedream, but imagine if hi-res thermal imaging was as simple as a point-and-shoot mobile phone camera. And as inexpensive. Time will tell; those few of us today making pretty pictures with thermal cameras are true pioneers.