Gaussian noise: Image Processing

As we all know, Gaussian Noise follows Gaussian or Normal distribution, and that distribution follows a $ BELL$ $ CURVE$ .

enter image description here

As we can see that most of the values are centered around the mean.

Now consider this image

enter image description here

When I add Gaussian noise to this image I get something like this

enter image description here

As we can see that the noise appears to be $ UNIFORMLY$ $ DISTRIBUTED$ throughout the image. There is no region where we can say that the noises concentrated around the mean value

So how can these be called Gaussian Noise?

The Code that I have used in octave is given below

 pkg load image;  I=imread('C:\Users\Hirak\Desktop\apple.jpg'); I=rgb2gray(I);  J = imnoise(I,'gaussian',0.02); K = medfilt2(J); imshow(J); 

Detailed explanation of Perlin Noise algorithmic complexity

I am doing a project in analysis of algorithm and I have been looking all over for something more complex than Perlin Noise is $ O(n \cdot 2^n)$ because of the doubling in $ n$ dimensions and array operations. Anyone know where there is more information? I have another month before our group gives the presentation.

External monitor visual noise on LTS 18.04

I am on Ubuntu LTS 18.04. I am using a Lenovo Yoga 920, i7 / 16gb. Intel Corporation UHD Graphics 620 (rev 07). The laptop screen is 4k.

When I connect my external monitor (usb-c to hdmi cable) and have it set to it’s native resolution (1680×1050) the screen has small specs of noise moving across it in a repetitive pattern. It also loses connection and re-establishes sporadically, maybe every minute, but sometimes longer. No screen tearing or other common issues I have seen searching online.

However, if I lower the resolution, it works fine. No problems at all.

I have tried using Wayland at login, but that did not help. And, I tried updating X from ppa, but I don’t know if I did that correctly.

I did not try much else because I couldn’t find any posts online with the same issue.

Can anyone help me resolve this? Let me know if any more information is needed and I will provide it promptly.

Microphone software boost is extremely low and boosts also noise

I am using a distribution based on Ubuntu. I have a problem that I have been facing on basically any Linux distro I have tried. I have a condenser microphone (NW-700) that under Windows sounds perfectly.

Under Linux tho it’s completely different. Normally on Windows I use boost function (that btw appears only if I have correct motherboard drivers installed) to boost microphone volume. Under Linux there is not any boost like this (as far as I know) and boosting it normally with PulseAudio volume control means extreme static noise (I can’t even hear myself over that noise).


My theory is that the motherboard (Asus Prime B250 Pro) has actually some hardware based booster that is controlled by this driver (which is not working under Linux).

Is there any way to solve it? I am connecting the microphone directly to motherboard.


xinput property ‘Synaptics Noise Cancellation’ doesn’t exist – Thinkpad x220 – jittery touchpad – ubuntu18.04.3

I just installed ubuntu on my thinkpad-x220 and my touchpad is extremely jittery / jumpy. If I don’t touch it my mouse stays still which is fine, but once I start moving my finger on the touchpad the mouse shakes and moves which is so annoying.

Apparently this is a well known issue, but I’m not having any luck using the recomended solution of xinput:

When I run xinput I see this:

root@martin-ThinkPad-X220:~# xinput ⎡ Virtual core pointer                      id=2    [master pointer  (3)] ⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)] ⎜   ↳ SynPS/2 Synaptics TouchPad                id=11   [slave  pointer  (2)] ⎜   ↳ TPPS/2 IBM TrackPoint                     id=12   [slave  pointer  (2)] ⎣ Virtual core keyboard                     id=3    [master keyboard (2)]     ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]     ↳ Power Button                              id=6    [slave  keyboard (3)]     ↳ Video Bus                                 id=7    [slave  keyboard (3)]     ↳ Sleep Button                              id=8    [slave  keyboard (3)]     ↳ Integrated Camera: Integrated C           id=9    [slave  keyboard (3)]     ↳ AT Translated Set 2 keyboard              id=10   [slave  keyboard (3)]     ↳ ThinkPad Extra Buttons                    id=13   [slave  keyboard (3)] 

I run this command:

xinput --set-prop "SynPS/2 Synaptics TouchPad" "Synaptics Noise Cancellation" 20 20 

but get an error message saying:

root@martin-ThinkPad-X220:~# xinput --set-prop "SynPS/2 Synaptics TouchPad" "Synaptics Noise Cancellation" 20 20  property 'Synaptics Noise Cancellation' doesn't exist, you need to specify its type and format 

13” MacBook Pro Retina (Early 2015) freezes all functions and screen then makes ticking noise

My MacBook has now frozen twice in the span of one week. The screen freezes on whatever I was working on, the trackpad freezes, and the keys do not input anything.

I’ve removed the back cover and gently dusted the inside using pressurized air, but the problem persists.

Here is an audio recording of the ticking noise in question:

Realistic channel noise patterns

I’m setting up a playful coding challenge for our programmers. It’s about coding theory. There are source, channel and sink. The task will be to implement an encoder for the source and a decoder for the sink. The encoded information will be transmitted over a channel with simulated garbling.

Now my question:

What common noise patterns do we encounter in real settings and how would their transformations look like?

What people talk about are for example:

  • band tapes (stressed at start and end)
  • defect memory (some bits are always off)
  • lightning strike
  • meteor shower

But they never mention how these patterns would look like.