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](https://publiclab.org/n/9372)_ [(/system/images/photos/000/018/533/original/Rosco_26_filtered.JPG) [](https://i.publiclab.org/system/images/photos/000/001/647/original/IMG_0025.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](https://store.publiclab.org/collections/diy-infrared-photography) 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: http://us.rosco.com/en And an article on the history of Rosco filters: http://www.rosco.com/spectrum/index.php/2016/11/decoding-the-language-of-color/ **** ## 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 | ||
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geobduffy | "Thanks for the quick response. I'd be happy to be a Low Alt Aerial Photo Guinea Pig for testing :) " | Read more » | almost 12 years ago | |||
cfastie | "Ned's plugin is available under downloads here: https://github.com/nedhorning/PhotoMonitoringPlugin. I still has a bit of a learning curve but offe..." | Read more » | almost 12 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 12 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 12 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 12 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 12 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 12 years ago |