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Other tri-color IR images

Infrared Processing TriColour
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#1 Stefano

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Posted 29 November 2020 - 22:54

I started this new topic since I thought the previous one was already complete, being my first attempts only. I have taken other images, and I am posting them here.

This is the first topic: https://www.ultravio...t-tri-color-ir/

As a reminder, the camera I used is a full-spectrum Panasonic DMC-F3, I used a Hoya R72 filter for the IR images and a white LED for the visible light references. Some tri-color images have been white balanced, I will say that for every image. Note: sometimes my camera doesn't autofocus, and usually (ironically) the IR images are sharper than the visible ones the camera was designed to take.

Channels:
Red: ~940 nm;
Green: ~850 nm;
Blue: ~730 nm.

Visible reference:
Attached Image: P1000684 - Copia.JPG

Tri-color IR (original):
Attached Image: somma 271 - Copia.jpg

I don't think I need to say this, but to be clear the brands shown are just random and there isn't the slightest intent to advertise them.
The first bottle from the left is water, the third one is denaturated alcohol 90°. They both appear bluish, but the alcohol is greener.

Pens, assorted colors. If the colors aren't clear, from left to right they are BLUE RED BLUE GREEN GREEN BLACK BLACK BLUE RED BLUE.
Visible reference:
Attached Image: P1000660 - Copia.JPG

Tri-color IR (original):
Attached Image: somma 268 - Copia.jpg

Full-size crop:
Attached Image: somma 268 - Copia (2).jpg

Some inks became transparent (red), others orange (blue), others red (green) and the black pens remained black. Black pen ink becomes transparent to IR when thin (see my pen ink filter).

Rodolfa

Visible reference:
Attached Image: P1000662 - Copia.JPG

Tri-color IR (original):
Attached Image: somma 269 - Copia.jpg

Amethyst (I am 99.9% sure it is that)

Visible reference:
Attached Image: P1000709 - Copia.JPG

Tri-color IR (white balanced):
Attached Image: somma 274 WB - Copia.jpg

Various minerals

The rock/mineral below has a quite strong orange fluorescence under 365 nm UV.

Visible reference:
Attached Image: P1000717 - Copia.JPG

Tri-color IR (white balanced):
Attached Image: somma 275 WB - Copia.jpg

Visible reference:
Attached Image: P1000725 - Copia.JPG

Tri-color IR (white balanced, almost identical to the original):
Attached Image: somma 276 WB - Copia.jpg

The middle specimen is actually green:
Attached Image: 20201129_212610(0).jpg

Visible reference:
Attached Image: P1000733 - Copia.JPG

Tri-color IR (white balanced, similar to the original):
Attached Image: somma 277 WB - Copia.jpg

The middle specimen is actually blue:
Attached Image: 20201129_212431.jpg

Bonus: a failed attempt. I tried to photograph an orange, but it slowly settled down and thus moved a bit. I processed the images anyway and this is the result (crop):
Attached Image: somma 278 - Copia.jpg

Thoughts and conclusions:

White, red, orange and yellow plastics come out usually white;
Blue plastics are usually yellow;
Green plastics and dark blue plastics are usually orange/brown;
Black plastics are often black.

Most minerals don't have strong IR false colors. Except for one strong yellow, all I got were shades of orange and pink, and a very pale blue from the amethyst.

I think I will take other images, probably 3-6, and I will post them here. If you have any suggestions (I am running out of ideas!), please share them here.

Edited by Stefano, 26 March 2021 - 22:06.


#2 colinbm

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Posted 30 November 2020 - 05:25

Interesting lot Stefano
The other minerals look like Agate to me....

#3 Stefano

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Posted 30 November 2020 - 08:13

Thanks Colin. It may be, I have no idea. I am sure only about the amethyst.

#4 dabateman

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Posted 30 November 2020 - 12:11

I actually really like the orange shot. From that angle, reminds me of the moon, through a cheap kids telescope.

#5 Stefano

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Posted 30 November 2020 - 12:55

I will re-try the orange. I should either give it time to settle or use a support.

Also, I tried a hand. I had to use my dad's hand, and the skin came out mostly white, maybe a tiny bit blue, and the hair on his arm became orange.

#6 Bernard Foot

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Posted 30 November 2020 - 13:31

Well done, Stefano. Looks like the technique is working well. And looks like you've got some rock samples that you can use for fluorescence work !
Bernard Foot

#7 Stefano

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Posted 30 November 2020 - 13:35

Yes, one day I will try fluorescence, both visible and infrared. The pink rock may be similar to a pink highlighter: they are both pink and they both fluoresce orange. Probably the fluorescence keeps going into IR, and in tri-color IR (with filters) it may be blue, since far red appears blue with this technique.

#8 Stefano

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Posted 30 November 2020 - 17:31

Ok, I have other 6 images. Now I really ran out of ideas, probably I will be set for a while. All tri-color IR images have been white balanced except for the heatsink one.

Orange, take 2

Visible reference:
Attached Image: P1000767 - Copia.JPG

Tri-color IR:
Attached Image: somma 281 WB - Copia.jpg

It seems my LEDs weren't perfectly aligned... but this is good enough for me.

Bananas

Visible reference:
Attached Image: P1000775 - Copia.JPG

Tri-color IR:
Attached Image: somma 282 WB - Copia.jpg

10 € banknotes, front and rear. What surprises me aren't the disappearing regions, this is a well-known trick in IR, but the colors I got. I have yellow, red and even blue, which isn't common in tri-color IR (except for water, sky and some filters).

Visible reference:
Attached Image: P1000816 - Copia.JPG

Tri-color IR:
Attached Image: somma 283 WB - Copia.jpg

Below is the heatsink I use with my LEDs. I don't have just one, this is one I didn't use yet. The black paint/coating becomes transparent in IR, and from the golden color it is clear that the absorption decreases as the wavelength increases.

Visible reference:
Attached Image: P1000793 - Copia.JPG

Tri-color IR:
Attached Image: somma 284 - Copia.jpg

Solar panel. I was expecting something interesting, but I was disappointed. Black in visible and IR, and probably also in UV.

Visible reference:
Attached Image: P1000785 - Copia.JPG

Tri-color IR:
Attached Image: somma 285 WB - Copia.jpg

Piggy bank, even though pigs are a bit different...

Visible reference:
Attached Image: P1000808 - Copia.JPG

Tri-color IR:
Attached Image: somma 286 WB - Copia.jpg

I really like this technique. Time-consuming and suitable only for static subjects (movement is your biggest enemy here), but in my opinion it is worth it.

Edited by Stefano, 30 November 2020 - 18:00.


#9 Andy Perrin

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Posted 30 November 2020 - 23:44

Stefano, you might want to retry the solar cell but very close up or macro even. Also the results will be very angle-dependent for the solar cell due to the thin layers involved.

The bank notes were interesting. I tried doing one of ours in SWIR (1500nm-1600nm) once:
Attached Image: Twenty dollar bill vis front UVP.jpg
Attached Image: Twenty dollar bill SWIR front_res UVP.jpg

Attached Image: Twenty dollar bill vis rear UVP.jpg
Attached Image: Twenty dollar bill SWIR rear_res UVP.jpg

Edited by Andy Perrin, 30 November 2020 - 23:55.


#10 Stefano

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Posted 01 December 2020 - 02:03

Thanks Andy, I will try the solar panel again. I don't think I can do macro, but I will try to be as close as possible.

It seems all banknotes or at least most of them have disappearing portions in IR. Usually NIR is deep enough, but SWIR of course works well.

US dollars have a disappearing rectangle (as you showed), and a green line in UVIVF. Euro banknotes are beautiful under UV. They are pretty much full of patterns, and have yellow and orange rings. I think the older ones were better, they had nicer patterns. If I find an old and a new one, I will try to post some UVIVF images (my first)!