arts102


Noise Definition, Discussion, References
Noise Definition
  

Noise is one of the classic problems and processes used in image processing work. Noise is random information. Signal is planned information. All signals have certain amounts of noise in them. Some of it is not visible. For instance when you take a digital photo in dark situations, you will notice that all the pixels have additional color noises added due to the fact that the camera is created to give best results at bright light levels. Read Image noise before proceeding further.

Noise / Signal
  

Engineering research is dedicated to improving systems, one way is to enhance signal over noise, signal being planned, ordered information, and noise, being unwanted, unexpected, unstructured information. New cameras are designed to feature higher resolution, greater precision with fewer noisy artifacts. Each new camera system has higher resolution, better conmpression, and lower noise.
Claude Shannon's Information Theory






Entropy
Random variable

Brownian Motion

  

C Shannon working at Bell Labs defined a mathematic theory in 1947 for the relationship of noise to signal titled "Information Theory". Information Theory adresses the quantification of information, leading to operations such as data compression, digital bits (1,0), entropy, etc. Shannon's paper (here)

Its impact crucial to space missions to deep space, MP3, invention of comptact disc, mobile phones, the internet, the study of linguistics, human perception, etc.

quantifies the uncertainty involved in predicting the value of a random variable
A random variable is whose value is unknown. Computers which are based on mathematical sequences, randomness has to be artificially created.
Brownian motion is the random movement of particles suspended in a fluid (schmidt)
Noise in Perception Research in visual perception for special effeects, psychology, science

Perlin [1] | Julesz [dot] | Eckstein | Ahlers Physics
Noise & Transformation in Art






Artworks

   Artists and composers tend to like noise. They use it in sound, in images, they also like to explore the metaphorical meaning of noise, for instance a "noisy system" tends to provide more stimulus than a calm one. Anything that shakes the viewer out of their normal perception will increase the viewer's alert state. Noise is used to stidu complexity, for instance its added to processes to create variations, and therefore allow for testing of the processes to see if its functionality is as expected.

Marey | Richter | Woods | Ruff | Polke [1][2]
Processing in Image & Audio


Schaeffer
Xenakis
Varese

Ikeda
Nicolai
YoutubeStuff

   Listen to the classical and contemporary sound artists working with noise:

Sound montage by 1940's French composer Pierre Schaeffer
Musique Concrete [1] sound works of the composerwho assembled soundtracks in the late 1940's. Xenakis [Orient-Occident],
rozart mix little noise in teh system

sonar 2010 [testpattern ][2][Berlin][ars electornica] | data.microhelix |
neue stadt |
Skrewell | d_time | s_wrl_time
Noise in Image Processing Image processing is a subset of signal processing. Music is linear, therefore 1 dimensional, where the image has an vertical and horizontal coordinates, and therefore 2D, or spatial.

Noise means any unplanned sound, or pixel value shift in an image. White noise pink, and brown noise are commonly used in electronic music. Noise in Photoshop is distributed as uniform, or as Guassian. This means that Guassian is usually in the form of a bell curve where more noise is present in the middle values, and unifrom means its uniformaly distributed between all the values from dark to light.

Noise Thru Compression

If you save a jpeg with very low compression, the process will add artifacts to your image. If you then open and resave again, additional artifacts will be added. If you continue, you will quickly see how the compression process has particular kinds of patterns that are imposed on the image, and could potentially be of interest in our study. Technical Description.
Image Processing Menu

Photoshop CS3 has an image processing menu that highlights all the functions that are specific to image processing. I highly recommend that you select this to let you know which tools are relevant for our study of Photoshop as an image processing tool. Do the following:
Open an image | Go to EDIT, MENUS | at SET, select IMAGE ANALYSIS
All of the relevant tools in Photoshop will now be highlighted.
Related Topics Filtering (low pass, high pass), convolutions. FFT (Fast Fourier Transform)