Why does a lit LED look pink or the wrong color in photos, and how can I capture it accurately?
Asked 11/11/2014
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When I photograph an illuminated LED, it often looks much brighter than it does to my eye and the color is inaccurate. For example, a red LED can appear pink even when I reduce exposure by about -2 EV. Changing white balance and using a faster shutter speed has not fully fixed it. Could this be caused by the LED spectrum not matching the camera sensor, or by infrared emission? What is the best way to photograph LEDs so their brightness and color look more accurate?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
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LEDs emit a narrow frequency band of light. Digital cameras detect color by looking at black and white luminance (brightness) sensors that go through a grid of colored filters (red, green and blue). If the frequency of light from the LED is narrow enough and doesn't match up well with the filters on the sensor, you can get odd looking color as the narrow frequency of light is largely filtered out and you only get a little bit of the edge where it bleeds over.
This is encountered a lot in LED stage lighting where you need to get special LED stage lights for ensuring good color when filming with digital cameras. The same principal applies to still cameras and single LEDs though.
As for the brightness, I doubt it is actually coming through as too bright relative to everything else, more likely, your just not seeing how much of a difference in brightness there actually is. While your eyes do have a similar dynamic range (the difference between the darkest and brightest spot) to a good modern camera, your eyes can shift much faster, giving an apparent dynamic range that is much wider. Your brain and eyes do this in the background very quickly without it really being obvious, but you rarely actually look directly in to a light source and if you do, your eyes normally narrow quickly to adjust. Direct emitted light would be considerably brighter than the surrounding reflected light in almost all cases.
Originally by user11392. Source · Licensed CC BY-SA 4.0
user11392
11y ago
0
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The main causes are overexposure and sensor/white-balance limitations, not usually infrared.
A red LED can look pink when the red channel clips: once it’s overexposed, color gets washed out. Lower the exposure until the LED itself is no longer blown out. If the rest of the scene becomes too dark, that’s normal—you may need to expose for the LED specifically.
White balance also matters. If whites in the scene don’t look neutral, correct WB first. Including a white or gray reference card can help you set it accurately in post.
There’s also a sensor issue: LEDs emit a very narrow band of light, and a camera’s RGB filters may not match that spectrum well. When that happens, even a properly exposed LED can reproduce with a slightly wrong hue. This is a known issue with LED lighting in both stills and video.
So: reduce exposure to avoid clipping, correct white balance, and be aware that some LEDs may still not render perfectly because of their narrow spectrum.
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