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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) ![]( ### 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
warren "We now have a great solution for this! !! and a kit available there. " | Read more » about 4 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 » almost 5 years ago
cfastie "Probably good that they didn't contact me. I would have said only "Blue filter?" " | Read more » almost 5 years ago
nedhorning "Yes - the author contacted me shortly before posting the blog " | Read more » almost 5 years ago
warren "@nedhorning @cfastie did you hear about this? We just learned of it! Amazing :-) " | Read more » almost 5 years ago
RehmaanMalik "Nice try Natalie Ui Developer @ RailsCarma & Carmatec " | Read more » almost 5 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 » about 5 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 » about 5 years ago
warren "I'm collecting up info about this here: [activities:raspberry-pi-infragram] and questions about..." | Read more » about 5 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 5 years ago
suman "Thank you guys....sorry for being late in replying... " | Read more » over 5 years ago
warren ":-) thanks, Chris!!! " | Read more » over 5 years ago
cfastie "Rosco 19: Rosco 2007:" | Read more » over 5 years ago
cfastie "I think the Public Lab Store will ship filters to Europe:" | Read more » about 7 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 » about 7 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 » over 7 years ago
kykytos "Is it important the station in which the photo is taken? I mean, how do you differ infrared reflected radiation from infrared emitted radiation (th..." | Read more » over 7 years ago
cfastie "Bob, this is a great idea. A secret admirer sent me one of these and I was very excited. I didn't know that any mortal could order them for only $3..." | Read more » almost 8 years ago
bobmathieson "anyone tried the Rosco sample book... only $3.95 from adorama. The swatches will not be big enough for front lens filters on SLRs but easily big en..." | Read more » almost 8 years ago
aguchosolano "Thanks! " | Read more » about 8 years ago
natalie "Yes that's correct. We have about 100 of the Infrablu filters left. After those are gone, all the new Infragrams have one each of #74, and #19. " | Read more » about 8 years ago
warren "Hi, aguchosolano - the Public Lab store ships internationally and will send Rosco #74 or #2007. I believe they're going to start shipping #19 as we..." | Read more » about 8 years ago
aguchosolano "Thanks cfastie! I am from Argentina, so I will try to contact providers that could send the filters to my country. " | Read more » about 8 years ago
cfastie "Theatrical gels are a good substitute for more precise filters. Rosco #19 "Fire" behaves much like Wratten 25A and costs $7.00 for a huge (20x24") ..." | Read more » about 8 years ago