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Manufacturers of LEDs mention color as a wavelength in nanometers. Is there any method or tool for estimating differences between colors?

For example, how to check if a LED is dark or light green? In other words, a tool for showing the difference, for example, between 500 and 570 nm green LEDs?

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  • \$\begingroup\$ Not sure how precise you really need to get, but if you need a range like that you can just look up a picture of the visible light spectrum to estimate it. For example this is the first result I found: sciencenotes.org/visible-light-spectrum-wavelengths-and-colors \$\endgroup\$
    – InBedded16
    Commented Dec 30, 2022 at 18:44
  • \$\begingroup\$ I want to be more precise. I know that there are differences between monitors nad I always get results misleading little. For example I ask to some nm -> RGB convertor tool. As far I used simple method of looking to the picture you posted, but I ask about something more accurate. \$\endgroup\$
    – Misaz
    Commented Dec 30, 2022 at 18:46
  • \$\begingroup\$ @Misaz A wavelength->sRGB converter tool is literally what an image like this is. \$\endgroup\$
    – Hearth
    Commented Dec 30, 2022 at 18:52
  • \$\begingroup\$ Just use a "system" with a prism to see a calibrated diffraction picture (?). \$\endgroup\$
    – Antonio51
    Commented Dec 30, 2022 at 18:58
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    \$\begingroup\$ I swear there must exist colour comparison cards and you would use them under a good CFI light source. \$\endgroup\$
    – DKNguyen
    Commented Dec 30, 2022 at 19:18

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There are a number of sites that have LED color charts, for example this one with a chart from Lumex that shows color, wavelength, and forward voltage or this one with a video and a color chart.

If you know the brand of LED you are planning to use you can check the manufacturers website to see if the have something similar specific to their product line.

I remember back in the 80s when we were trying to find LEDs that met out requirements for a project we just ordered samples from multiple manufacturers and tested them, so there's always that option.

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It would be great if an LED manufacturer would supply an assortment of their LEDs of various wavelengths, but a quick search produced no joy. However, if you are looking for a particular color, such as green, there are only a few in that color range, and you could order maybe 5 of each for a few dollars (shipping would be the main expense). Then you can make a test fixture to power each of them and choose whichever looks best to you (assuming your need is aesthetics and not lab standard). Here is a chart from LEDtronics showing their range of LEDs and corresponding wavelengths:

LED Color Chart

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Pure, saturated colors as produced by LEDs are actually not present in the common sRGB colorspace used by images on the internet as well as most PC monitors:

 https://commons.m.wikimedia.org/wiki/File:SRGB_chromaticity_CIE1931.svg#mw-jump-to-license

But assuming the color calibration on your display is reasonably accurate, you can get a pretty good idea from those diagrams. For example, a 520nm LED will be slightly more green than the maximum you see in the above image.

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  • \$\begingroup\$ Please provide a link or citation for the image you copied into your answer. The policy for this site is that all material copied from other sources must have proper attribution. \$\endgroup\$ Commented Dec 31, 2022 at 11:50
  • \$\begingroup\$ @ElliotAlderson Put the full wikimedia link into the description. \$\endgroup\$ Commented Dec 31, 2022 at 15:59

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