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ARTICLES IN THE BOOK

  1. Acoustics
  2. AKG Acoustics
  3. Audio feedback
  4. Audio level compression
  5. Audio quality measurement
  6. Audio-Technica
  7. Balanced audio connector
  8. Beyerdynamic
  9. Blumlein Pair
  10. Capacitor
  11. Carbon microphone
  12. Clipping
  13. Contact microphone
  14. Crosstalk measurement
  15. DB
  16. Decibel
  17. Directional microphone
  18. Dynamic range
  19. Earthworks
  20. Electret microphone
  21. Electrical impedance
  22. Electro-Voice
  23. Equal-loudness contour
  24. Frequency response
  25. Georg Neumann
  26. Harmonic distortion
  27. Headroom
  28. ITU-R 468 noise weighting
  29. Jecklin Disk
  30. Laser microphone
  31. Lavalier microphone
  32. Loudspeaker
  33. M-Audio
  34. Microphone
  35. Microphone array
  36. Microphone practice
  37. Microphone stand
  38. Microphonics
  39. Nevaton
  40. Noise
  41. Noise health effects
  42. Nominal impedance
  43. NOS stereo technique
  44. ORTF stereo technique
  45. Parabolic microphone
  46. Peak signal-to-noise ratio
  47. Phantom power
  48. Pop filter
  49. Positive feedback
  50. Rode
  51. Ribbon microphone
  52. Schoeps
  53. Sennheiser
  54. Shock mount
  55. Shure
  56. Shure SM58
  57. Signal-to-noise ratio
  58. Soundfield microphone
  59. Sound level meter
  60. Sound pressure
  61. Sound pressure level
  62. Total harmonic distortion
  63. U 47
  64. Wireless microphone
  65. XLR connector

 

 



MICROPHONES
This article is from:
http://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio

All text is available under the terms of the GNU Free Documentation License: http://en.wikipedia.org/wiki/Wikipedia:Text_of_the_GNU_Free_Documentation_License 

Peak signal-to-noise ratio

From Wikipedia, the free encyclopedia

 

The phrase peak signal-to-noise ratio, often abbreviated PSNR, is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. Because many signals have a very wide dynamic range, PSNR is usually expressed in terms of the logarithmic decibel scale.

The PSNR is most commonly used as a measure of quality of reconstruction in image compression etc. It is most easily defined via the mean squared error (MSE) which for two mn monochrome images I and K where one of the images is considered a noisy approximation of the other is defined as:

\mathit{MSE} = \frac{1}{mn}\sum_{i=0}^{m-1}\sum_{j=0}^{n-1} ||I(i,j) - K(i,j)||^2

The PSNR is defined as:

\mathit{PSNR} = 10 \cdot \log_{10} \left( \frac{\mathit{MAX}_I^2}{\mathit{MSE}} \right)  = 20 \cdot \log_{10} \left( \frac{\mathit{MAX}_I}{\sqrt{\mathit{MSE}}} \right)

Here, MAXI is the maximum pixel value of the image. When the pixels are represented using 8 bits per sample, this is 255. More generally, when samples are represented using linear PCM with B bits per sample, maximum possible value of MAXI is 2B-1.

For color images with three RGB values per pixel, the definition of PSNR is the same except the MSE is the sum over all squared value differences divided by image size and by three.

Typical values for the PSNR in image compression are between 30 and 40 dB.

See also

  • Signal-to-noise ratio
  • Video quality
  • Subjective video quality

External link

  • Program for PSNR measurement in BMP files and video
Retrieved from "http://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio"