Calculating Color temperature and Color Rendering Index

In summary: JacobiIn summary, you will need to generate the CIE coordinates for your source, and then use one of the aforementioned programs to calculate the CRI and CCT.
  • #1
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Hi, I've been a lurker here for a while but I finally have a question. I was wondering if there is a simple formula to calculate the Color Rendering Index(CRI) and Correlated Color Temperature(CCT) of a white light source.. To do this I would also need (I think) to make a some points on a chromacity diagram. Right now, all I have is the wavelength emissions of the light in an excel spreadsheet... So basically, I want to know how to convert from wavelength emissions, to a chromacity diagram, to CRI and CCT.. I've looked quickly for some software to do this but it was $1000... Thanks..
 
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  • #3
You will like this tool: http://www.radimg.com/dlcolorcalculator.htm
It's a free program and if I remember correctly allows you to load in your own spectrum (which I think you have, judging from your info) and do some color calculations on it.

Otherwise the abovementioned links, coupled with this one should provide you with the answers. It is not as hard as it looks :)
http://en.wikipedia.org/wiki/Color_temperature
 
  • #4
Thank you both so much! These links really helped (especially the color calculator, thanks Kelemvor)!
 
  • #5
  • #7
You can find it http://www.radiantimaging.com/index.php?q=downloads/ColorCalculator" [Broken] now. They changed their main webaddress.
http://www.radiantimaging.com/index.php?q=downloads/ColorCalculator [Broken]
 
Last edited by a moderator:
  • #8
Hi Folks,
I am trying to use color calculator software in order to calculate color and coordinates for my own SPD (Intensity vs wavelength curve). Would you please let me know how to upload my graph into color calculator program. It does give me some instructions bout it is not clear to me if I have to save an data file in the color calculator folder. Any info is highly appreciated. Thanks
-Janardan
 
  • #9
Would you guys know the availability of a free software to calculate CRI for a given SPD curve and direct it to me. Thanks
-janardan
 
  • #10
spectral analysis

Hello all.

I realize this is quite an old post, but if anyone has stumbled upon this thread because they have use for spectral analysis and/or composition, please check out the ColorTools package available on the LabVIEW Tools Network. A thorough description and trial of the package are available here: http://interfaceinnovations.org/colortools.html . In addition to a LabVIEW Toolkit, we have executables available for use with LabVIEW RunTime.

The package will calculate all CIE (xy, uv) color coordinates, CRI, CQS, as well as generate xy and uv color plots, color gamut, Planckian locus, and many many more features necessary for describing and analyzing color.

Please feel free to contact me directly here or at support@interfaceinnovations.org

Kind Regards,
Colin
 

1. What is color temperature?

Color temperature is a measure of the color appearance of light. It is measured in Kelvin (K) and is used to describe the warmth or coolness of a light source. Lower color temperatures (around 2700K) appear warm and yellow, while higher color temperatures (around 6000K) appear cool and blue.

2. How is color temperature calculated?

Color temperature is calculated by measuring the color of a light source and comparing it to the color of a perfect black body radiator at a given temperature. The color temperature is then assigned a numerical value in Kelvin based on this comparison.

3. What is the Color Rendering Index (CRI)?

The Color Rendering Index (CRI) is a measure of how accurately a light source can reproduce the colors of different objects compared to a natural light source. It is measured on a scale from 0 to 100, with a higher CRI indicating better color rendering abilities.

4. How is the Color Rendering Index (CRI) calculated?

The CRI is calculated by comparing the color rendering of a light source to a reference light source with a known CRI. The colors of eight standardized test colors are used in this calculation, and the resulting score is the CRI for that light source.

5. What factors can affect color temperature and CRI?

The color temperature and CRI of a light source can be affected by the type of light source (e.g. incandescent, fluorescent, LED), the quality of the light source (e.g. color consistency), and the environment in which the light is used (e.g. ambient lighting, color of surrounding surfaces). Additionally, the color temperature and CRI can vary depending on the manufacturer and model of the light source.

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