Public Lab Wiki documentation

Infragram Filters

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The Infragram project has used a variety of filters to make Do-It-Yourself infrared cameras, as well as infrared-visible multispectral cameras. This page is about choosing filters for different purposes.

Red vs Blue

Both blue and red filters are intended to block most visible light in one channel, to then use that channel for near-infrared light. This way, a single camera can be used to take simultaneous visible light and near-infrared light photos -- one in the red channel, one in the blue channel (we discard the green channel).

Most recent DIY efforts on Public Lab have focused on red filters, but early on we used blue filters. A red filter (the most common conversion we see on Public Lab as of October 2017) results in vegetation appearing pale blue, and a blue filter typically results in vegetation appearing pale yellow.

Left: pale blue from a RED filter; Right: pale yellow from a BLUE filter. Images by @mathew and Eclectis students


Background on filter choice

There's a lot of research about this choice here:

Filter sources

We've been using Rosco theater gels as filters, and we currently carry the red Rosco Fire # 19 in the Public Lab store

Red filters include:

  • Rosco Fire # 19

Blue filters include:

  • Rosco # 2007
  • Rosco # 87

Also see this research on various Rosco filters:

Title Author Updated Likes Comments
How to do the white-balancing for the RED filter? @xmv79667 over 4 years ago 1
Hacked Infragram Raspberry Pi camera now on the International Space Station @warren over 6 years ago 3
NIR, Rosco fire #19 and my elph 300HS from Christmas @admaltais almost 9 years ago 1
Video streaming with infragram on intel edison (ubilinux) @pjsbill over 9 years ago 2
Canon SD4000IS as Infragram @warren almost 10 years ago 9
Announcing the Infragram Point & Shoot @mathew about 10 years ago 11
A Wratten 25A replacement from Rosco? @mathew about 10 years ago 8
NDVI with Canon A2300, APM Hexacopter DJI550, Help @andresc4 over 10 years ago 23
A490 Rosco 2007 initial results @patcoyle about 11 years ago 1
NDVI from Infrablue @cfastie about 11 years ago 4
Infrafilters @cfastie about 11 years ago 0
Artichoke filter search @cfastie almost 6 years ago 0
Middlebury Meetup @cfastie about 11 years ago 0
Rosco! @cfastie about 11 years ago 9
Superblue @cfastie about 11 years ago 31

And the Rosco website:

And an article on the history of Rosco filters:

Exposed negative film

To make a camera take only near-infrared photos, you can use a piece of exposed negative film as a filter. This will block most visible light (since the red, green, and blue channels are blocked) but will allow infrared light.