Question: Spec Cam to Infragram w/the flip of filter? (Rosco "Fire" #19)

natalie is asking a question about ndvi
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by natalie | July 29, 2014 23:12 | #10996

What I want to do

I would like to see if the "low-cost" webcam we are using currently for our Desktop Sprectrometer Kit will work as an Infragram webcam by installing the red filter (specifically the Rosco "Fire" #19)

First attempt and results

I cut and installed a circular red filter under the lens of the spec cam and screwed it back on. Then I plugged it into the labtop and opened Hit begin and so far have collected two images, one with raw capture selected. The second image which didn't turn out so good, is the preset NDVI capture with red filter installed, no colormap.(right here--->) 222.jpg The blob in the middle is a tree, as seen from my office window.

Update Second attempts and results

Okay, here we have a new SpecCam in focus with no filter, raw capture on One pic of me the other of a live plant on the left, and a dead leaf branch on the right, with a white poster board for the background. The third picture is with the office fluorescent lights on and natural lighting coming from the right office window.

RawMe.jpg Me Raw Capture No Filter Live_Dead.jpgLive Plant (left) Dead (right) Raw Capture No Filter

Live_Dead2.jpg Same as above but with lighting (office and natural)

So why is the plant brown and not green. Do I need to white balance it? and how?


These pictures are from Raw Capture with red filter and then blue filter taped over the lens.

MeRawRed.jpg Raw Capture w/Red Filter taped over lens RawMeBlueFilter.jpgRaw w/Blue

Live_DeadRed.jpg Raw w/red Live_DeadRawBlueFilter.jpg Raw w/blue

The focus was a little off with the red filter pics. I think it is because the filter wasn't all the way tape against the lens.

After NDVI Capture with red filter over lens followed by blue filter over lens.

NDVIRedfilter.jpgMe, red filter NDVI red capture MeNDVIbLUEfilter.jpgMe, blue, NDVI blue capt

Live_DeadRedNDVI.jpgLive (left) Dead (right), red filter NDVI red capture

Live_DeadNDVIbluefilter.jpgLive (left) Dead (right), blue filter NDVI blue capture

Live_Deaddefault.jpgLive (left) Dead (right) with the default colormap, red filter NDVI red

Live_DeadNDVIbluefiltercolormap.jpgLive (left) Dead (right) with the default colormap, blue filter NDVI blue


The next 3 were taken in the sandox using my clip on webcam I use for Skyping. First is Raw with no filter, second is Raw with Red Filter, and third is NDVI capture with Red Filter ColorMap. I didn't do blue filter testing on this since it was a last minute comparison. @mathew maybe you can answer where my Skype webcam came from and the cost????

WebcamRaw.jpg Me w/live plant Raw Skypecam capture

WebCamredfilterraw.jpg Me w/live & dead plants red filter Raw capture

WebcamNDVIRedfilter.jpg Me w/live & dead plants red filter NDVI colormap capture

What do you think folks?!? @warren, @mathew, @cfastie

Questions and next steps

What do I need to do to get quality captures? How do I set the white balance? Has anyone else tried this yet? Is anyone else willing to try it and/or walk through it with me? Maybe I should try a blue filter? What is the benefit of one over the other in this case? @warren @mathew @cfastie @liz @GreenLeaves @NoahHochman

Why I'm interested

The webcam we use for the Desktop Spectrometer Kit is much more cost effective to produce. If we could also use if for the Infragram Kit it would allow us to bring the cost down and offer a more attractive price point for both individuals and bulk buyers.


Trying for full res....



Hi natalie- it looks like the focus is a bit off... You actually don't have to remove the lens or anything to test this, you can just tape some red filter in front of the lens.

Do you think you could photograph some live and dead plant material, like dead leaves and live leaves? The tree is just a bit blurry to infer much.

Actually if you took the same photo with red and blue filters and also a regular photo that'd allow us to compare more thoroughly. Is that possible?

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The blurry photo looks interesting though...


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I also updated with red/blue filter information. I believe all webcams are CMOS sensors so I'm not actually sure how we were able to find a webcam that did work with a blue filter.

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white balance is tough-- I only remember control of exposure in UVC. look at these programs:

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Okay check out my updates. @warren, @mathew, @cfastie

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Hi, Natalie - thanks for updating, but your photos are really tiny -- is there any way you can post them at full resolution? They look promising, but it's hard to tell how good the photos are... thanks!

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There's an application for linux-- GUVCView that should let you capture full resolution 1200x1600) in the settings.

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I guess. What a pain in the butt. I tried for about an hour to post them at the original size and the wiki just said updating, perpetually and never added the photos. Finally I had to "save picture" from the recent pictures page as is and they finally loaded. I'll have to try the app a little later. There are a lot of pictures.

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Mathew just had trouble uploading lots of photos too, so perhaps it chokes on large uploads. If you could just upload the one raw image with a red filter and the live/dead plants, that would be plenty, and feel free to post it in a comment. We just need to see this one photo at full res:



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The plant is dying but it still have some green to it. How is this?

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:-/ doesn't look good. I think without white balancing it, we're going to have a hard time using this cam.


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What about a different filter? Or how do we white balance these?

Next Steps suggestions.

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Nice try Natalie Ui Developer @ RailsCarma & Carmatec

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