Fourier series visualization

Odinbc · **Posted:** Mon Feb 01, 2016 12:51 am **(#1)**

Nice Fourier series visualization.

Gimp & G'MIC tutorials.
G'MIC Tutorial #3 : Descreen Image using Fourier Transform

Pat625 · **Joined:** May 12, 2015 **Posts:** 4693

Wow! Those are really good results. I have photos that need that. Hope I can remember how to use it.

Wallace · **Posted:** Mon Feb 01, 2016 4:10 am **(#3)**

I've seen this tutorial before, but I can't recall when.
I do believe the author of this tutorial is also a GC member,
if I'm not mistaken.
The FFT filter produces quite impressive results.
It's unfortunate that I haven't found an opportunity to utilize this filter yet.

dinasset · **Posted:** Mon Feb 01, 2016 5:21 am **(#4)**

IMO it's a function not easy to understand by a non mathematician, thus it would require a written tutorial (a PDF I mean, not a video), with a couple of examples (input -- output -- all the steps inbetween).
My weakness: I'm unable to take advantage from a video...

Rod · **Joined:** May 16, 2010 **Posts:** 16161

Nice results.

OFF TOPIC:
I want to know where he got the animated windows fx.

Is that WindowsFX? Or is that a freeware?

jazzon · **Posted:** Mon Feb 01, 2016 7:43 am **(#6)**

I'm with dinasset on this one. I am fairly good at math and fourier stuff baffles me.

garagecoder · **Posted:** Mon Feb 01, 2016 8:07 am **(#7)**

One page I found useful in understanding them is here (commercial site but the page is just an info page):

http://qsimaging.com/ccd_noise_interpret_ffts.html

Might look scary at first glance but if you understand the basics (i.e. it's just transforming into frequencies) it does start to make sense!

rich2005 · **Joined:** Mar 04, 2011 **Posts:** 2612

@ Rod
The effect in the video is from linux and in particular the KDE (desktop environment) wobbly windows effect

and generally

You do not need to be a mathematician to understand Fast Fourier Transform. Lots of people can drive and do not understand how an engine works.

Things to remember with FFT
It is for coherent noise
FFT direct to make a defect map
Use the same colour as the map paint out the defects
(G'mic seems to have changed a bit, used to be a nice black map) If using G'mic do not go into the "junk underneath"
FFT Inverse to unscramble

Not the best of examples but all that condensed into four images

Attachment:

fft.jpg [ 356.7 KiB | Viewed 6307 times ]

Rod · **Joined:** May 16, 2010 **Posts:** 16161

Thanks Rich.

doronf2 · **Joined:** Mar 06, 2015 **Posts:** 308

Hi
I need Help.
I can not find this filter in my G'MIC .

Thanks
Doron.

snelltheta · **Joined:** Jan 31, 2016 **Posts:** 3

doronf2 wrote:

Hi
I need Help.
I can not find this filter in my G'MIC .

Thanks
Doron.

It should be under Frequencies.

doronf2 · **Joined:** Mar 06, 2015 **Posts:** 308

Thanks
Thanks

doronf2 · **Joined:** Mar 06, 2015 **Posts:** 308

Hi
Thanks for your help.
I am attaching two pictures before and after effect.

DORON.