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St. John's Seminary LWIR pano

LWIR Infrared
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#1 Andy Perrin

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Posted 03 February 2018 - 16:56

St. John's Seminary is one of innumerable Catholic institutions in my area of Boston, and it has a lot of very nice neo-gothic buildings that photograph wonderfully in LWIR (which is an inherently gothic-looking photographic medium, to my way of thinking). The trees, in particular, look like something out of Wuthering Heights.

FLIR E60, 43 image panorama.
Tools: Photoshop for stitching, MATLAB for putting all the histograms on the same scale and for colorizing, SmartDeblur for deblurring, exiftool for extracting RAW.

Taken at 1am, air temp was 8°F/-13.3°C.

Attached Image: St-Johns-Seminary2_res.jpg

I'm not sure colorizing the image improves it, but it's traditional for LWIR photos, so if you want to know how it looks with a traditional FLIR "iron" colormap, here it is.
Attached Image: St-Johns-Seminary2_res-iron.jpg

Edited by Andy Perrin, 03 February 2018 - 17:04.


#2 Andrea B.

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Posted 03 February 2018 - 21:05

yessir, this is very wuthering !!

And if I ever get stuck outdoors in freezing weather I'm going to head for that cupola thingie on the roof!!

Have you played with the colour version to perhaps decrease the saturation? Just curious if a "tinted" version would work??
Andrea G. Blum
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#3 Mark

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Posted 03 February 2018 - 21:06

I tend to like grayscale better for thermal IR images because it seems to show subtle details better, where the color versions appear to have saturation issues. Although, color is more appealing, in general. I'm torn.

#4 Andy Perrin

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Posted 03 February 2018 - 21:16

Andrea, you can't directly change the saturation on that photo without making it look very peculiar indeed (try it, you'll see what I mean). I could choose a different colormap, though, although most of the ones I've seen are equally saturated. Some nice ones may be found here (scroll way down):
http://peterkovesi.c...cts/colourmaps/

Mark, the reason for using color to begin with is to show fine details better. Look at the trees in the background (or at the tiny branches) for example.

Edited by Andy Perrin, 03 February 2018 - 21:19.


#5 Mark

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Posted 03 February 2018 - 22:22

I agree that color can make things appear more or less obvious (perception phenomenons). But its all the same data, just mapped differently, and when color is introduced saturation effects can actually reduce perception of detail as high saturation is actually a reduction in the number of discrete levels of [given color]. I still like color images more than grayscale though (just a personal preference).

#6 Andy Perrin

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Posted 04 February 2018 - 00:00

Mark, you just said two contradictory sentences in a row. Either it helps perception or it hurts it, not both! But lots of research backs up the former. I think we agree that the amount of information in the image is fixed, no matter how you divvy it up. Not all the colors in that colormap are maximally saturated, no matter how it looks, either.

Edited by Andy Perrin, 04 February 2018 - 00:02.


#7 Andrea B.

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Posted 04 February 2018 - 02:51

Not really contradictory because one statement is about colour in general and the other about saturated colour.
Colour helps until there is too much saturation at which point it begins to hurt.
Andrea G. Blum
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#8 Cadmium

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Posted 04 February 2018 - 03:05

Oops, please delete this post, wrong topic.

Edited by Cadmium, 04 February 2018 - 04:16.


#9 Andy Perrin

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Posted 04 February 2018 - 03:06

Andrea, Mark:
Well perhaps I'm misunderstanding then. Are we talking about whether the image hurts your eyes (yes, it does) or whether it's conveying useful info? Anyway, while that iron colormap certainly is bright, it is not 100% saturated. I plotted the saturation and while sometimes it is 100%, it wiggles around a bit:

Attached Image: saturation.png

Edited by Andy Perrin, 04 February 2018 - 03:07.