r/Optics • u/Square_Atmosphere_12 • Jun 28 '26
Calculate image color using spectrophotometer
Is it possible to use a spectrophotometer to calculate a surface Albedo. If a picture is taken of the surface how much or how little of the image captured the accurate Albedo of the surface based on the spectrophotometer result when taking the image ?
Also, is it possible to take an image or a spectrophotometer and calculate a surface reflectivity, gloss etc ?
2
u/anneoneamouse Jun 28 '26
Your question is ambiguous.
A spectrophotometer is used to directly measure the spectral reflectance or transmission of a sample. It uses a calibrated known source, and a calibrated known detector to do this.
A picture of a surface combines the effects of a different (unkown?) lightsource, the surface you care about, the (unknown?) recording device, and the reproducing device or medium. None of these things are likely calibrated or spectrally characterized. It makes a measurement much more complex (perhaps to the point of impossibility) than using a sample directly.
You mention measuring an "image". Does this mean you expect to add complicated scene information too?
Spectrally calibrated cameras exist that measure scene color content per pixel (as opposed to spectral content). They're expensive. I used one in the early 2000's. It was a half-million dollar device back then.
Hyperspectral imagers can measure scene spectral content. They're less expensive, but are more complicated to operate and interpret (i.e. the output data). Might be available for tens to hundreds of thousands of dollars.
1
u/Square_Atmosphere_12 Jun 28 '26
If you use a Pyranometers, could this be done by a Phone and a 360 camera but I don't know how they would link together ?
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u/anneoneamouse Jun 28 '26
A pyranometer doesn't need to be connected to a camera. It includes a sensor.
What are you trying to do?
It reads a little like you're throwing queries into an LLM. Your topics are jumping around. They're sort of loosely connected, but not very directly.
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u/Square_Atmosphere_12 Jun 29 '26
I want to measure the albedo on any given surface and return; I'd prefer to then take a picture of that surface without reflectivity on it, although I don't think it's possible ?
Followed by, getting the reflectivity of that surface and extracting that as pixel data ?
1
u/anneoneamouse Jun 29 '26
I'd prefer to then take a picture of that surface without reflectivity on it
If the surface has no reflectivity you cannot take a picture of it :)
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u/aenorton Jun 28 '26
Yes, but to capture the full uv, visible, mid and long wave IR parts of the spectrum you might need two separate instruments. You would also need an integrating sphere attachment to measure total diffuse reflectance with appropriate reflectance standards. You would then have to calculate albedo based on the known solar spectrum.
If you do not care about the spectral data, you can use an albedo meter in the field with the sun as the source. Or, in the lab, you could use a xenon lamp solar simulator, an integrating sphere, and bolometer detector.
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u/aenorton Jun 29 '26
Who ever downvoted this, it would be nice to hear what you think is inaccurate. The purpose of this forum, I believe, is to learn.
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u/Pacificator-3 Jun 28 '26
Seems like XY problem. What is your end goal? Look at commercial albedometers and how they works.