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 | ||
|---|---|---|---|---|---|
| admin9o | "Hello all and what a great guide! I have managed the hardware part fine but used a blue instead or red lens cover thanks to this tutorial but I’m ..." | Read more » | about 1 year ago | |||
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| warren | "Very impressive - and yeah, what a great cheap camera... that filter switcher is amazing! " | Read more » | over 3 years ago | |||
| amocorro | "@DS501st What a great way to combine your interests! Thanks for documenting your process and sharing for the Public Lab community to replicate :hea..." | Read more » | over 3 years ago | |||
| warren | "We now have a great solution for this! https://publiclab.org/infrapi !! and a kit available there. " | Read more » | over 5 years ago | |||
| cfastie | "The blue filters used block red light, so the red channel records a lot of NIR, so NGB. The red filters used block blue light, so the blue channel ..." | Read more » | about 6 years ago | |||
| cfastie | "Probably good that they didn't contact me. I would have said only "Blue filter?" " | Read more » | about 6 years ago | |||
| nedhorning | "Yes - the author contacted me shortly before posting the blog " | Read more » | about 6 years ago | |||
| warren | "@nedhorning @cfastie did you hear about this? We just learned of it! Amazing :-) " | Read more » | about 6 years ago | |||
| RehmaanMalik | "Nice try Natalie Ui Developer @ RailsCarma & Carmatec " | Read more » | about 6 years ago | |||
| stevesteve | "Thanks Chris, Actually as I read more papers I am finding that many of the newer references are using: NDVI=(NIR-R)/(NIR+R) rather than the blue an..." | Read more » | over 6 years ago | |||
| cfastie | "I don't know of published results of studies comparing red and blue filters. Red light has been used for the visible part of the NDVI equation for ..." | Read more » | over 6 years ago | |||
| warren | "I'm collecting up info about this here: https://publiclab.org/wiki/raspberry-pi-infragram [activities:raspberry-pi-infragram] and questions about..." | Read more » | over 6 years ago | |||
| ashishkochaar | "It is really very awesome. I am also trying to take the selfies like this but when I was at Chase Routing Number Texas then I had taken a lot of se..." | Read more » | over 6 years ago | |||
| suman | "Thank you guys....sorry for being late in replying... " | Read more » | almost 7 years ago | |||
| warren | ":-) thanks, Chris!!! " | Read more » | almost 7 years ago | |||
| cfastie | "Rosco 19: https://publiclab.org/notes/mathew/04-29-2014/a-wratten-25a-replacement-from-rosco Rosco 2007: http://legacy.rosco.com/filters/SED.cfm?t..." | Read more » | almost 7 years ago | |||
| cfastie | "I think the Public Lab Store will ship filters to Europe: https://store.publiclab.org/collections/diy-infrared-photography/products/infragram-diy-f..." | Read more » | over 8 years ago | |||
| GFFchris | "Hello, I wanted to ask if anyone has an idea on how to order the Rosco filter to Europe / Germany? Many Thanks! " | Read more » | over 8 years ago | |||
| cfastie | "The angle from which the photo is taken and the angle of the sun do influence the NDVI result. NDVI values are a function of how much red and NIR l..." | Read more » | almost 9 years ago |