10 Feb

Pros and Cons of Wide Dynamic Range

Recently I wrote about night vision and green screen, and I assumed that it was a trade off.  It kind of is, but maybe not in the way I thought.

Every time I make a change to EvoCam or to the Hikvision settings, something new occurs. Not necessarily good or bad, just new. And times like this I am simply baffled.

Again, it’s time to look under the hood.

I thought I had turned off the so-called night vision — there is no setting called night vision for my camera, but we’ll get to that — when I made adjustments to the white balance. I had assumed that when I adjusted the white balance from default (AWB1) to Nature Light, that the darker screen meant the feature was disabled. I also assumed that making this change made the green screens go away. It may have, but it could be other things. I recently did a fresh macOS install and I have made many changes to the EvoCam settings since I last had a green screen occur. Can’t assume anything at this point.

When I consolidated the tabs, I noticed that the night vision (just easier to say that, at this point in this narrative) returned; and no changes to the camera settings were made. I scratched by head, but it was time for bed. As long as there weren’t any green screen errors, I would be fine with this freaky change at least until I had time to sleep and think.

In the morning, I checked the footage for the 24-hour timelapse, and was please that not a single frame was green.  Win, I thought. Then I checked the daylight-only timelapse, and saw the problem.

With the night vision back on, there was enough light that EvoCam’s light sensor thought it was daylight. Therefore I had two identical timelapses, and would continue to have two unless something was done.

I played around with the Hikvision interface, and noticed it was the WDR options under Backlight Settings creating the night vision effect. I did a quick video search for my camera model and WDR and learned a bit more about the setting. I decided to leave it on and check the results for the daytime images the next day.

But not before creating a test Action in EvoCam to see if I could still recreate the daylight-only timelapse without the light sensor or disabling WDR.

There is an Action setting for “every day when it is daytime (or nighttime)” which uses location services in macOS to determine sunrise and sunset at the location. This means that the resulting timelapse will start exactly at sunrise and end exactly at sunset. However, unlike the conditions option in use for the sunset and sunrise images, there is no way to offset that time. Not ideal, but it appears to be my best option. I know at least one person — possibly my only viewer — who says she likes the daylight option. And I have plans for the daylight videos to be stitched together. So as of today this method will replace the old light sensor version of the daylight movie.

My opinion so far is that WDR handles shadows in a superior way to when it is turned off; especially around the barn and tree line. The colors appear a bit brighter to me, as well. Ergo, for now, more changes, tweaks, and experimenting… the way I like it.

If it ain’t broke, it ain’t fun, right?

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