IFD-x Red Eye "512*384" for GBP60 - caveat emptor - Page 1
Forum section: electronics / general

author: Ultrapurple
author_rank: Super Contributor
timestamp: December 17, 2019, 03:41:28 pm
content: Yes, that caught my eye. 512 x 384? Now that's an odd resolution. But that's what it says on eBay (and presumably elsewhere). Selected quotes:The imaging resolution is 512*384 pixels, the temperature sensitivity is 0.1℃, the absolute accuracy is ±1.5℃, and the refresh frequency is up to 64Hz.Measuring temperature range: -40~300℃Temperature measurement accuracy:Temperature sensitivity: 0.1℃@1HzAbsolute temperature error: ±1.5℃ (middle area)Refresh rate: 0.5~60HzAll this for GBP 60 (US$80)?A strong smell of rat, methinks.Judging by the almost total lack of definition in the sample images (whicharethermal) I suspect it's no more than 60x80 thermal pixels. Anyone know any more info?Caveat emptor!

author: bap2703
author_rank: Regular Contributor
timestamp: December 17, 2019, 04:57:58 pm
content: It's just another thermopile sensor disguised as a "camera"...32*32 displayed as 65536*655361Hz physical first order cutoff sampled at 512 GHzReal thermal imagers already use dodgy specs, amateurs just followed the trend with even less regulation

author: Fraser
author_rank: Super Contributor
timestamp: December 17, 2019, 05:21:35 pm
content: It uses a MLX90640 32x24 pixel thermopile sensor and interpolation to whatever crazy resolution spec the seller wishes to claimhttps://www.melexis.com/en/product/MLX90640/Far-Infrared-Thermal-Sensor-ArrayGranted IRISYS managed to make simple thermal cameras with a 16 x 16 and 32 x 32 pixel IRISYS REDEYE FPA, but at least they were honest about the optical resolution.Since the release of the MLX90640 there have been several “thermal cameras” that have appeared on eBay and other internet sales outlets. They are OK for learning about the basics of thermal imaging and great as an educational project or demo at low costI would have loved to own such a unit in the early 1990’s !Fraser

author: Ultrapurple
author_rank: Super Contributor
timestamp: December 17, 2019, 10:27:41 pm
content: So... here's a philosophical point: what level of native pixel resolution does it take to make a 'camera'?I leave out of this question the single pixel mechanically scanned devices and propose only to consider staring array technology. Also, let's leave aside NETD and similar measures of finesse. If it can respond to my thumb hovering above water ice then that meets the definition (waves cheekily towards the early Seek cameras: you're in!).At what point is it no longer an 'image' from a 'camera' but just a collection of heat samples?Answers on a postcard please (or, failing that, here).Ultrapurple

author: Vipitis
author_rank: Frequent Contributor
timestamp: December 17, 2019, 10:46:13 pm
content: to me this is a question of spatial resolution. 80x60 does not work(for a 80° diagonal). 160x120 does work post stamp sized. a printed out PPi of like 160 from an arms length viewing distance.another measurement that seems less subjective is how many pixels does your brain need to identify a face. A letter/number. an animal, etc.Ambiguity remains but QVGA+ is very acceptable for me right now and VGA seems sufficient.Camera is anything that captures a scene in a time instance and is able to reproduce it. we do had a longer discussion about he philosophical idea of a camera I the photography Discord a while back and it ended with very conflicting solutions.

author: Fraser
author_rank: Super Contributor
timestamp: December 17, 2019, 11:08:43 pm
content: Ultrapurple,A good question and one I have pondered previously when fellow forum members have made comment that a certain low resolution thermal Imager is not truly a “Camera”.To be pedantic, “Camera” May not even be a correct term for what we are talking about. See this page......https://www.dailywritingtips.com/what-does-in-camera-mean/I actually prefer the term “Thermal Imager” as that accurately describes the device. The unit creates an “Image” that reflects a scene in the thermal domain. How much Resolution or detail is contained in the “Image” very much depends upon the needs of the user. An image can be useful with very few data points if those data points contain the information needed by the user to INTERPRET the thermal scene. A good example of this ‘argument’ is the Omega OS XL thermal imaging device. It contains a visible light colour camera that produces the visible light domain scene on the screen. Over that visible light image is overlaid a very low resolution matrix, each square or which is a pixels thermal domain data. It can show the user heat distribution in the scene and even measure temperature, but without the visible light image the low resolution thermal ‘image’ is hard to interpret and correlate to the scene being viewed. That said, if the low resolution thermal pixel matrix can be aligned with an optical viewfinder, it could be used as a thermal energy distribution tool without the need for the visible light camera. There is also the projected matrix technique that shines a carefully aligned rastered laser on the scene so that the user can see the correlation of the pixels to the target scene. Is this a camera ? Is this a thermal imaging device ? I prefer to call it a thermal imaging device as it allows the user to SEE the distribution of thermal energy within a defined scene in order to assess such energy and its meaning in the scenario. As few as one pixel in an 8x8 pixel matrix may be able to identify an overheating electrical breaker or mechanical bearing in a scene. A single pixel IR thermometer of the correct specification might be able to do the same measurement, but it would likely take longer and not show the measurement pictorially with reference to its surroundings.So I prefer the term “Thermal Imager” but understand that when people see a lens at the front of a box and a display at the rear, they like to call it a “Camera”. Provided everyone understands what is meant and the specification/capabilities of a particular “Thermal Camera” I have no great issue with the terminologyFraser

author: bap2703
author_rank: Regular Contributor
timestamp: December 18, 2019, 04:51:37 pm
content: I like to think that a "camera" is a device the provides you the luxury of deciding afterwards what is interesting!Capture more information than what will be necessary (space and time) --> Look up afterwards at what interesting stuff was captured.Even with that there isn't a clear line between camera and non-camera.For example is your computer mouse a camera ?Quote from: Fraser on December 17, 2019, 05:21:35 pm*switches browser tab, casually buys a 1$ cooled imager*