Exploring the Near Infrared (NIR) Spectrum - Questions & Answers

[Dilbert]

I have confidence that the moderators can correct my choice of forum if a mistake was committed. Although I do believe that this is the correct forum.

I start this thread not because I know much about the Near Infrared (or NIR) spectrum but because I am of great need to know. Research in fields closer to my expertise that lately have escalated far beyond the boundaries of my knowledge has raised some concerns and some questions have sprung to my mind.
I would prefer to find someone with larger knowledge of this area that I could discuss with because the questions will become severely more difficult; but yet, I can start simple here.

My logic tells me some things, and I guess that it is Hope that makes me still cling on to it. Anyway, here are my first basic questions.

I have read somewhere that the NIR spectrum was not bound to Heat (that heat did not affect it); nor should colour affect it. But at some images, it seems to do; whilst on others it doesn’t.
What affects the (black and white) shade that an NIR camera can render? Is it heat, is it colour, is it amount of exposure?
I would say that it is all of them, but yet I have seen pictures where the same colour renders totally different colours so could it be fabric? But that does not really fit either because striped clothing with different colours gave 2 different shades of grey.

Anyway, I do not have a clue about this so can any of you help me?

 

[AndyW]

I would first like to applaud your curiosity and willingness to learn about a new topic. It is always important to seek out knowledge and expand our understanding of the world around us.

To address your questions, the Near Infrared (NIR) spectrum is indeed not affected by heat or color. This is because the NIR spectrum is outside of the visible light spectrum, so it is not influenced by colors that we can see. However, the NIR spectrum can be affected by the amount of exposure, as well as the material or fabric that is being imaged.

The shade that an NIR camera can render is determined by the amount of NIR light that is being reflected off of an object. This reflection is affected by the material's properties, such as its texture, thickness, and chemical composition. For example, a smooth surface will reflect more NIR light than a rough surface, resulting in a brighter shade on the camera. Similarly, a thick fabric will absorb more NIR light, resulting in a darker shade on the camera.

In terms of color rendering, it is important to note that NIR cameras do not capture colors in the same way that our eyes do. Instead, they measure the intensity of NIR light reflected from an object and convert it into shades of grey. This is why you may see different shades of grey for the same color on different objects.

I hope this helps to answer your questions and provides a starting point for further discussion and exploration of the NIR spectrum. As always, it is important to continue researching and seeking out information from reliable sources. Best of luck in your learning journey!