How can I get more balanced outdoor images from a machine-vision camera in high-contrast light?

Asked 12/15/2023

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I’m using a machine-vision camera outdoors and seeing very harsh results: bright areas blow out while dark areas block up, even after adjusting exposure, gamma, and gain. I’ve also tried normalizing the image in YUV/HSV without getting a pleasing result.

The goal is to make the output look more natural, closer to a phone or action camera image. Is this mainly a lens issue, a post-processing issue, or a limitation of the sensor? What should I look at for better results in outdoor scenes with a wide range of lighting conditions?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

2y ago

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This is mostly a dynamic-range and processing issue, not a lens fix.

In real outdoor high-contrast scenes, many cameras cannot capture both deep shadows and bright highlights in a single exposure without compromise. Marketing DR figures for machine-vision sensors may not reflect real-world photographic results. Also, phones and action cams usually do heavy computational processing, often combining multiple exposures automatically.

What to try:

  • Expose to protect highlights first; once highlights are clipped, they’re gone.
  • If highlights still clip at the shortest usable exposure / smallest aperture, use an ND filter to reduce incoming light.
  • For scenes with extreme contrast, use exposure bracketing and merge exposures (HDR).
  • Be sure the camera has appropriate IR/UV blocking if you want natural-looking visible-light images.

A different lens generally won’t solve blown highlights and crushed shadows by itself. If your goal is “smartphone-like” output, the biggest difference is usually multi-frame HDR and tone mapping, not optics alone.

UniqueBot

AI

2y ago

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The camera I am using quotes excellent dynamic range from what I can tell, 65dB or 20+ stops.

Practically, no camera has that kind of dynamic range - even a top of the range full frame sensor like the Canon R3 has "only" 15 stops of dynamic range in actual use (source: DxoMark). There may be some theoretical world in which the sensor in that camera has 20 stops but it's not going to get anything like that in real-world use.

If so what is a good thing to look for in image postprocessing / lens selection that might make the photos look as pleasing as if they came off an action cam or smartphone

You can't - the sensor just isn't good enough. Sorry.

Originally by user11371. Source · Licensed CC BY-SA 4.0

user11371

2y ago

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