how to extract Near-IR (NIR) from an RGB image

I have an RGB image and i have to extract Near-IR (NIR) portion can any one tell how ro process please

Answer 1

[Image Analyst]

You can't. The information for that spectral band simply isn't there. Red captures around ~550 nm to ~700 nm. Near IR is > 700 nm wavelength. In fact camera manufacturers for most cameras put an infra red filter in front of the sensor, specifically to block (filter out) the infra red light.

If you have some special format where you somehow captured the NIR image and stored it along with the RGB images in a file, then you'll have to use an image reading function that can handle that format, such as the tiff class reader.

Answer 2

[Kostas Vogiatzis]

I am looking on the same thing for academic purpose but my camera has no filter so i take visible and nIR image.. Look this link may help. (Sorry for 4 years late answer :p but i post it if someone looks for it)

[Jayakrishna S]

I need your link, please.

[Image Analyst]

@Jayakrishna S I don't know what "your link" means. @Kostas Vogiatzis didn't post a link of his own, but posted a link with an article from Hank Dietz from the University of Kentucky (great guy and quite brilliant - I've met him several times in person).

https://www.engr.uky.edu/directory/dietz-hank

http://aggregate.org/hankd/

[Vedant]

h!

This paper talks about seperation of NIR and Visible Light image. An Acquisition Method for Visible and Near Infrared Images from Single CMYG Color Filter Array-Based Sensor - PMC (nih.gov)

Can you elaborate about this further.

Answer 3

[Walter Roberson]

On cameras that do not filter the infra red, and whose sensors are capable of capturing it (some NIR does fall within the sensitivity of typical CCD devices), the NIR portion simply shows up a contribution to the intensity of red.

Consumer cameras do not record the frequency of the light they receive: all they know is that they received a certain total intensity of light within a band of frequencies.

If you have a camera that does not filter out the infra-red or whose infra-red filter you can remove, and which has sensors able to pick up that range, then if you put in a filter that blocks visible light, what remains to be picked up will be just the infra-red. For more details, please see the comments in this post