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Fun with Pi NoIR and Filters

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Experimenting with the Pi NoIR (913-2673) prototype and blue and infrared filters.

Following on from my first attempt at building a night vision time-lapse rig, I thought I'd see how the Pi NoIR performs when used with filters. Of course, you get pretty interesting results just using the camera in daylight and without any filtering; as can be seen below images have a reddish hue and infrared reflecting plants appear curiously radiant..

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Blue filter

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The blue filter shown above came with the prototype camera, but I have to admit to knowing very little about it, beyond that the intended application is detecting disease in plants. Details of how this works can be found on an excellent page over on the Public Lab website.

Below can be seen the same shots from above albeit with the blue filter added. Not surprisingly the red toning has gone, but plants appear to be further emphasised.

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Uploading the first of these to the processing service at infragram.org didn't give quite the result I was expecting, and further reading and experimentation is required.

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IR filter

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Next I tried the camera with a photographic filter that blocks light below 850nm in wavelength. As can be seen from the picture above, this looks completely opaque to the human eye.

First, a shot without the filter.

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Not at all unpleasant and has something of a Kodachrome — or if you must, Instagram — feel to it.

Below is the same shot with the IR filter used.

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Note that no post processing has been used and this is still a colour image. A characteristic IR shot, with the blue of the sky blocked and so it appears much darker, with radiant clouds and brilliant silvery leaves.

Simple post processing can be used to enhance the effect, and the image at the top of this post is the same as the one below albeit with the contrast enhanced.

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Even just photographing the sky through branches resulted in a pleasing image.

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Finally, a shot of a distant hillside bristling with silvery trees. The out of focus objects at the bottom of the frame are the leaves of privets which the camera was balanced upon.

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I have a feeling I'm going to be having a lot more fun experimenting with the Pi NoIR!

Andrew Back

Buy a Pi NoIR at RS (913-2673)

Open source (hardware and software!) advocate, Treasurer and Director of the Free and Open Source Silicon Foundation, organiser of Wuthering Bytes technology festival and founder of the Open Source Hardware User Group.

25 Oct 2013, 10:32

Comments

October 15, 2015 12:11

4l3x wrote:
> Hello, I just want to know if it’s possible to add an IR filter in front of the NoIR
> camera and have the same picture of the normal camera?

This would seem to make sense and my understanding is that the only different is the lack of an IR blocking filter. However, I have not test this.

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October 15, 2015 02:53

Hello, I just want to know if it’s possible to add an IR filter in front of the NoIR camera and have the same picture of the normal camera?

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November 5, 2014 19:56

What process was used to install the filter into the pi camera module? Did you just use the filter outside of the module?

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