• Ultraviolet Photography

Queen Anne's Lace, UVIVF w/ "Nemo," Noise-reduction Stacking

Fluorescence Processing UV Lighting
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#1 Andy Perrin


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Posted 13 August 2020 - 16:33

Since I'm doing the Queen Anne's Lace by every method lately, here is the UVIVF, which was startlingly pretty. The main technical component here was an attempt to subtract off the background light since the plant was slightly illuminated by street lights. I took two batches of photos, one with the 15W UV torch (hereafter called "the Nemo") and the other without it. Then I averaged both separately, and subtracted the two pics after averaging to remove the noise. Since the only difference between the two is the UVIVF and/or any contamination from the torch, the hope is that it will remove the effect of the spurious lighting. I think it was mostly a success, since the background became quite black.

The camera setup was essentially the same as in the previous zinnia thread.

Visible reflectance, illuminated by streetlights. This is the averaged photo. I also adjusted exposure to make the scene visible (it looks black otherwise with the original exposure settings). Also (for display purposes, but not in the image subtraction), I white balanced on the outer petals.
30 photos x F/8, ISO500, 1/4"
Attached Image: Visible light-Mean UVP.jpg

UVIVF + streetlights
38 photos x F/8, ISO500, 1/4"
Attached Image: Queen Anne's Lace UVIVF-Median UVP.jpg

UVIVF after subtracting streetlights in Photoshop
(UVIVF + streetlights) - (streetlights) = UVIVF hopefully
Attached Image: Queen Anne's Lace UVIVF-Median with background subtracted UVP.jpg

Crop on the UVIVF:
Attached Image: Queen Anne's Lace UVIVF-Median with background subtracted crop UVP.jpg

1-1 Crop of the visible:
Attached Image: Visible light-Mean 1-1 crop UVP.jpg

1-1 Crop of the UVIVF:
Attached Image: Queen Anne's Lace UVIVF-Median with background subtracted 1-1 crop UVP.jpg

I will say, the averaging really drives the noise almost to nothing. Since the Starry Sky Stacker program has tools for evaluating image quality and accepting/rejecting each photo individually before stacking, and the camera takes all the photos in a batch, the actual time for taking and processing these photos was about an hour start to finish. There is no reason not to employ this procedure for almost every photo I take of stationary subjects, in fact, because the quality improvement is so dramatic.

Edited by Andy Perrin, 14 August 2020 - 00:40.

#2 Stefano


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Posted 13 August 2020 - 17:08

It really resembles a starry sky, almost as your software was made for this (or the other way around).

#3 Cadmium


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Posted 13 August 2020 - 22:30

Yeah, that last one is my favorite! :smile:

#4 colinbm


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Posted 14 August 2020 - 01:33

Beautiful Queen Anne's Lace to Fairy Lights.

#5 Andrea B.

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Posted 03 September 2020 - 16:36

(I'm a bit late to comment, sorry.)

I really enjoyed seeing one of my favorites, Queen Anne's Lace, in UVIVF. And I'm now lamenting the fact that I did not shoot it in UVIVF when I had the chance so many times in New England.
Excellent processing technique, too.
Andrea G. Blum
Often found hanging out with flowers & bees.