netd - Page 1
Forum section: electronics / general

author: johnelot
author_rank: Contributor
timestamp: October 20, 2019, 07:33:58 am
content: i have a chinese minir384 type core , it is listed as 80mk - i find the image outside fairly washed out even on max gain , i can see a cow or sheep ok but the background merges into grey - i am thinking of getting a 50mk version but wondered if anyone would know how much better this would be , i am hoping it would pick out more details in the background , please let me have any advice if you have knowledge of this - thanks - john

author: bap2703
author_rank: Regular Contributor
timestamp: October 20, 2019, 08:30:38 am
content: That's probably more a rendering issue: the embedded software has to decide how to translate the measured infrared intensity into a displayable image.In your case it's probably the temperature span that is too wide + the rendering algorithm might be crappy.Do you have any control over these two?

author: johnelot
author_rank: Contributor
timestamp: October 20, 2019, 09:08:53 am
content: there is only control over the gain /brightness thru keypad , it could be that being a few years old the software is out of date now but i will be looking for a good small size core in 640 and really would like to find out how much difference the netd makes (i dont know how accurate or optomistic they can be when measuring them of course) i realise the software can play a big part in image quality - but are che chinese good on this or are they all much the same ?some of them are said to be 40mk and even 30mk in their literature

author: Vipitis
author_rank: Frequent Contributor
timestamp: October 20, 2019, 10:57:44 am
content: you may just be experiencing depth of field. Lenses for thermal cameras are very low f ratio. Can you adjust focus? NETD won't help you there.

author: johnelot
author_rank: Contributor
timestamp: October 20, 2019, 12:12:39 pm
content: yes i can focus it in ok , it just seems to wash out whenthere is only a small temperature difference in the background and i was thinking the high 80netd could account for that so i wondered if a 50mk would bring out more details in the scene and how it affects thisi can turn the gain full to get a little better but then if i turn to look at a hotter thing it is too bright(or black dependant on polarity )it just does not drag any detail out if the temperature difference is small - i have other thermal items that are much betteri have looked for comparisons for netd's - video's etc. but cant find much

author: Vipitis
author_rank: Frequent Contributor
timestamp: October 20, 2019, 05:05:16 pm
content: sounds like you just have issues with the histogram scaling. If clarity is important it might be a chance to look into ICE(DRS) or DDE(FLIR) capable products.

author: johnelot
author_rank: Contributor
timestamp: October 20, 2019, 08:02:59 pm
content: yes i will look for one with some kind of enhancement - most of the cores i have looked at quote DDE , but i dont know if its as good as the likes of flir, guess i will find out

author: Bill W
author_rank: Super Contributor
timestamp: October 25, 2019, 10:50:55 am
content: Some thoughts,The NETD for a camera is copied from the sensor data sheet (or even the datasheet of the sensor that they copied....)Sensor NETD only applies in the sensor manufacturer test facility.You do not know if the test conditions are applied in the camera.You do not know if the ADC is the same bit noise as in the camera.NETD would not reduce with bad fixed column noise, while a low contrast image presentation might well be used to hide this.The choice of display and late stage image processing has no bearing on NETD, as NETD is a statistically generated figure (noise of pixel/response of pixel).Simple scene stretching is easier to do (especially in an FPGA camera) than a histogram equalisation, as noted in some of the other replies.regardsBill