esaofeccola
Posts: 7
Joined: Wed Nov 09, 2016 12:07 pm

Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 8:10 am

Hello everyone,

this one is so off-topic so I decided to share it with you:

yesterday, I was playing with my camera around my desk, and took some pictures of the Official case for RasPi Zero, with the camera module running, connected to my Asus Zenpad tablet via AP-WiFi config on Zero W.

Lighting was dim and the image appeared too dark, so I opened the original .jpg in GIMP, adjusted the levels quite a bit, scaled the image down to 800x600px and downsampled to 72dpi, exported as .jpg, optimising the image down to 52% quality.

At this point, I didn't notice anything out of ordinary. After a while I took another look of the image and found some debris starting from where the Zero W antenna is, and ending to the tablet... Checked the lenses and camera sensor, all clean, no dust, hair or debris. The debris had turned visible at some point after my edits on the image!

I've found no explanation for this, other than the debris is the Wifi signal.

Today, I tried to replicate my adjustments with the original image, no luck, couldn't reveal the "signal" again. I should have saved a working copy in GIMP instead of just exporting it as .jpg. I'm going to investigate this further someday.

All this is totally confusing, and I'm asking, have any of you had similar experiences photographing WiFi devices?
I've seen some experiments visualising the signals by photography, but they look like pretty lightpainting to me.

Attached the image with the "signal" visible, original image (2.3Mb) is also available, just ask if you think I'm crazy and just doodled something on it.
Attachments
official-zero-case-4.jpg
"Signal" visible
official-zero-case-4.jpg (41.97 KiB) Viewed 3750 times
Last edited by esaofeccola on Thu Mar 30, 2017 10:12 am, edited 1 time in total.

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DougieLawson
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Re: Did I just take a picture of Zero W WiFI signal?

Thu Mar 30, 2017 8:13 am

You've lost too much resolution and detail by crushing the pic to fit the silly forum limit.
Put the original image on http://imgur.com post the IMGUR link on here.
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esaofeccola
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Joined: Wed Nov 09, 2016 12:07 pm

Re: Did I just take a picture of Zero W WiFI signal?

Thu Mar 30, 2017 8:34 am

Hello Dougie,

here you go:

Signal visible after the abovementioned edits:
http://i.imgur.com/WuJdXIH.jpg

The original image:
http://i.imgur.com/NF98s9g.jpg

gregeric
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Re: Did I just take a picture of Zero W WiFI signal?

Thu Mar 30, 2017 8:58 am

I think your cat jumped on your mouse whilst your back was turned.

Kinda cute how it looks like the wiggles you draw in Feynman diagrams for photons. One clever cat!

esaofeccola
Posts: 7
Joined: Wed Nov 09, 2016 12:07 pm

Re: Did I just take a picture of Zero W WiFI signal?

Thu Mar 30, 2017 9:39 am

@gregeric,

I know I'm a bit on a thin ice here, it's haunting but it's real. No cats, no April Fools.

It could be just the electromagnetic radiation captured by the camera sensor, luckily revealed through image manipulation process.

I take it as a cool, once in a lifetime experience.

Heater
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Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 10:33 am

Picture of a WIFI signal? Really, this is the most absurd speculation I have heard for ages.

Do you really expect a WIFI signal to jump between Pi and tablet in a concentrated line like that?

WIFI signals are radio waves. They have a wave length on the order of half a foot. They radiate in all directions.

Besides no camera is ever going to respond to them.

I have no idea what that squiggle is. Perhaps a fly went by during exposure.

jamesh
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Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 10:34 am

The photon receptors on the camera cannot receive the frequency of the Wifi signal, so this is not that.

If you have invented a radio wave camera, you will of course be very rich and in line for a Nobel prize!
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
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startrek.steve
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Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 10:34 am

Its not the motherboards LED shining through the case is it?

Steve
Pi 2 running LibreElec Krypton, Pi 2 running Wheezy Desktop, Pi 1 headless Wheezy, downloading Radio, Pi 1 running Picore headless Media Server, Pi Zero to be an Old Time Radio Project. Pi 3 testing. Pi Zero W downloading Radio shows headless.

esaofeccola
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Joined: Wed Nov 09, 2016 12:07 pm

Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 10:44 am

Hello everyone,

now I see how confusing this really is, not just for me.

I can assure no pixels are added by me or the famous fly, the wiggled line just appeared there after my basic edits, and I can't understand why it starts from the Zero W antenna. If not the WiFi signal, maybe another radiation source on 0W?

Bad thing is I can't reproduce this phenomenom with the original image, maybe you can?

gregeric
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Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 10:49 am

The wiggly line is not present in the original photo. It seems to have been introduced in the edit process. Can you reproduce it, repeating the same image manipuluations?

esaofeccola
Posts: 7
Joined: Wed Nov 09, 2016 12:07 pm

Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 11:02 am

@gregeric,

like I mentioned, I can't reproduce the adjustments to the levels, (can't remember what the settings were :( ), only the scaling, downsampling and export is what I can reproduce properly.

I wish I'd saved a GIMP .xcf

Heater
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Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 11:43 am

esaofeccola,
...maybe another radiation source on 0W?
Let's be logical:

It's not there in the original picture.

It is there in the edited picture.

You can recreate similar enough image manipulation steps to reproduce it.

Conclusion: It's almost certainly an artefact of whatever image manipulation you did.

esaofeccola
Posts: 7
Joined: Wed Nov 09, 2016 12:07 pm

Re: Did I just take a picture of Zero W WiFi signal?

Thu Mar 30, 2017 11:49 am

@Heater ,

I guess you're right.

@jamesh ,

could you please close or remove this topic before I loose my good nights sleep?

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