[SS2S-Main] Re: Infrared webcam

  • From: "Lampe, Mattias SLC CT PEK" <mattias.lampe@xxxxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Sun, 18 May 2014 14:52:43 +0800

Hi David,



I suppose there are probably many ways of doing it. I used GIMP (a free image 
processing tool, maybe comparable to Photoshop) and a plugin named GAP that 
allows importing videos. The frames of the video will be represented as layers 
of a single image, and it is possible to apply filters or other transformations 
to all layers (i.e. all video frames) at once.



The filter I used is called “gradient map”. There are a number of predefined 
color gradients, but it’s also possible to define one’s own. I modified an 
existing one to create a gradient from dark blue over cyan, green, yellow, 
orange to red. After applying the “gradient map” operation to the image, the 
dark parts of the image will be mapped to the “cold” colors and the bright 
parts to the “warm” colors.



I takes a bit of processing time (depending on the resolution and number of 
frames in the video), but only a few mouse clicks.



“Gradient map” seems to be the “official” term for it, so I think the function 
will have the same name in Photoshop or other programs.



It shouldn’t be too hard to even apply this kind of operation “on the fly”, in 
real-time when recording the video, but that probably requires a bit of 
programming.



Have a good day!



Mattias



From: sugarshot-bounce@xxxxxxxxxxxxx [mailto:sugarshot-bounce@xxxxxxxxxxxxx] On 
Behalf Of waaslandwolf
Sent: Saturday, May 17, 2014 4:51 PM
To: sugarshot@xxxxxxxxxxxxx
Subject: [SS2S-Main] Re: Infrared webcam



Mattias,

Great work! I am curious how you did the gradient mapping post-processing, care 
to elaborate?

Cheers,
David.



On Fri, May 16, 2014 at 9:22 AM, Lampe, Mattias SLC CT PEK 
<mattias.lampe@xxxxxxxxxxx<mailto:mattias.lampe@xxxxxxxxxxx>> wrote:

Hi all,



after some experimenting I have to correct my previous statement that a 
modified webcam (after removal/exchange of the IR filter) is unsuitable for 
thermal imaging.



Here are my learnings:

-          Objects hotter than approx. 260 degrees centigrade (about 500 
degrees Fahrenheit) seem to “light up” in the near infrared image. The hotter 
the brighter, so at least a relative temperature comparison is possible, to 
some extent. The tip of a hot soldering iron, for example, appears to shine 
quite brightly when looking at it through a modified webcam.

-          Hot combustion gases show up brightly in the IR image, even if they 
are invisible to the naked eye. (Not sure if it’s the CO2 or some other gas 
that causes the effect.



As a proof, here are some videos taken simultaneously with three cheap webcams 
of the same brad and model. One had the IR blocking filter removed, anouther 
one had the blocking filter replaced by a filter blocking visible light (i.e. 
only letting IR pass to the sensor), and the third camera was not modified at 
all.



The so-so quality of the videos is not due to the camera but due to the slow 
computer used for recording and encoding. If the videos don’t play in your 
browser, downloading them may help.



This is me frying an egg as seen by a normal webcam (visible light only):

https://onedrive.live.com/redir?resid=6838BE39B86A56AC!178&authkey=!AKrXza_7QKYre8s&ithint=video%2c.mp4

Please note the familiar short, blue gas flame.





Looking only at the IR componente with a modified webcam, the flame looks 
totally different:

https://onedrive.live.com/redir?resid=6838BE39B86A56AC!176&authkey=!AOAS5uk5p0QffiA&ithint=video%2c.mp4



The hot gas moving upward is visible, and after shutting down the flame you can 
see the metal frame “glowing” for quite a while. The frying pan itself does not 
light up because it never really exceeds 200 degrees C.



Here is a post-processed version of the video with a so-called gradient-mapping 
applied to the IR video:

https://onedrive.live.com/redir?resid=6838BE39B86A56AC!177&authkey=!AKwVxXkHqhw0Z_k&ithint=video%2c.mp4



The camera that only had the IR blocking filter removed but no blocking filter 
for visible light installed took the following video:

https://onedrive.live.com/redir?resid=6838BE39B86A56AC!179&authkey=!AOZAg8XGkhGL0aQ&ithint=video%2c.mp4



(The videos were recorded simultaneously, and the lights in my kitchen are 
fluorescent ones, containg very little IR. Things look quite a bit different 
under incandescent lights.)





So after initial doubts I do see some value in using modified webcams for IR 
imaging of rocket motor tests. Compared to low-end FLIR cameras the resolution 
is higher and the cost is nearly negligible (less than 15$ for the cameras I 
used). You can observe the flow of exhaust gases and see where things get 
really hot (>260 degrees), and I could imagine that IR penetrates the smoke a 
little bit better than visible light.

Absolute temperature measurements, however, would probably be impossible or at 
least require quite a bit of calibration work.





Only a single egg was hurt in the process of recording the four videos ;-)  
(The other 11 eggs from the same box will be hurt later.)

Hope it’s interesting. I’ll send the cameras to Vicente, who started this 
thread.



Have a good day!



Mattias





















From: sugarshot-bounce@xxxxxxxxxxxxx<mailto:sugarshot-bounce@xxxxxxxxxxxxx> 
[mailto:sugarshot-bounce@xxxxxxxxxxxxx<mailto:sugarshot-bounce@xxxxxxxxxxxxx>] 
On Behalf Of Lampe, Mattias SLC CT PEK
Sent: Sunday, May 04, 2014 10:12 AM
To: sugarshot@xxxxxxxxxxxxx<mailto:sugarshot@xxxxxxxxxxxxx>


Subject: [SS2S-Main] Re: Infrared webcam



Hi,



I think removing the internal IR filter works with most webcams, and if you 
want to make sure you ONLY see the infrared but not the visible part of the 
spectrum, you can add a filter that only lets infrared light pass. A piece of 
overexposed and developed color negative film (like from the beginning of a 
film roll) works quite well for that purpose. It blocks nearly all visible 
light and is quite transparent for IR. If you know someone who still shoots 
pictures on film or someone who did so in the past and kept the negatives, they 
should be able to find a suitable piece of material.



Not sure how you want to use the IR camera, but you should be aware that it 
will not be a thermal imaging device. It will be sensitive only to near 
infrared, and in order to emit those wavelengths a body must be quite hot 
already, i.e. close to glowing.



I have a few unused webcams at home and will check if they can be converted.



Have a great day!



Mattias



From: sugarshot-bounce@xxxxxxxxxxxxx<mailto:sugarshot-bounce@xxxxxxxxxxxxx> 
[mailto:sugarshot-bounce@xxxxxxxxxxxxx] On Behalf Of James Fackert
Sent: Saturday, May 03, 2014 1:18 AM
To: sUGAR sHOT TO SPACE LIST
Subject: [SS2S-Main] Re: Infrared webcam



here is one, $30.
http://www.adafruit.com/products/1567



On Fri, May 2, 2014 at 9:53 AM, Lyn Berry 
<lyn_berry@xxxxxxxxxxx<mailto:lyn_berry@xxxxxxxxxxx>> wrote:

Hi
I am no expert but if memory serves webcams contain an IR filter. If the filter 
is simply removed the webcam becomes much more sensative to the IR part of the 
spectrum.
QED
Regards,
Lyn Berry



On Friday, 2 May 2014, 12:52, Vicente Alvero Zambrano 
<vicente_alvero_14@xxxxxxxxxxx<mailto:vicente_alvero_14@xxxxxxxxxxx>> wrote:

Hi,



Does anyone know and is willing to turn a webcam into a webcam with infrared 
vision for the series of motors VIC and to study the ablative materials?



Cheers

Vicente Alvero







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