Infragram Filters

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]( [![](/system/images/photos/000/018/533/thumb/Rosco_26_filtered.JPG)(/system/images/photos/000/018/533/original/Rosco_26_filtered.JPG) [![](]( ### Background on filter choice There's a lot of research about this choice here: [notes:red-vs-blue] **** ## 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: [notes:rosco] 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. ...

Author Comment Last activity Moderation
cfastie "Ned's plugin is available under downloads here: I still has a bit of a learning curve but offe..." | Read more » almost 10 years ago
geobduffy "Do you have a source for Ned's ImageJ plugin? I'm very curious about that. Also, I may have gotten ahead of myself with excitement...Do you think t..." | Read more » almost 10 years ago
geobduffy "Thank you for sharing this information. Your results are very promising. I am struggling to come up with a way to capture imagery that can be used ..." | Read more » almost 10 years ago
warren "It'd be neat to test the roscoe with our spectrometer against their spectrum graph. I was excited to see Jeff Hecht working on testing some filters..." | Read more » almost 10 years ago
warren "Super exciting! an important step will be to compare this result to NDVI produced with two cameras Excited to see that step too. Maybe it's just..." | Read more » almost 10 years ago
mathew "I definitely want some Rosco #2007! this is a great idea, it seems like what we need to do is find or make a custom white balance card for the Ros..." | Read more » almost 10 years ago