Creating Bluish Noise With Minimal Compute - Revision history

MSaarna at 15:21, 4 July 2025

2025-07-04T15:21:28Z

2024-05-23T17:09:19Z

2024-05-23T17:03:46Z

2024-05-23T16:54:51Z

2024-05-23T15:36:17Z

2024-05-23T15:31:04Z

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2024-05-23T14:44:11Z

2024-05-23T14:41:14Z

2024-05-23T14:39:09Z

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 Blue noise is a type of noise with a power density that increases with frequency, giving it a high-pitched, hissy sound. Visually, it manifests as a pattern with minimal low-frequency components and a relatively even distribution of points, and is frequently used for dithering. Blue noise is often used for its aesthetically pleasing randomness, since numbers don't clump together as they would with truly random (white noise) sources.
-== Saarna's Bluing Algorithm ==
+== Bluing Algorithm ==
 Blue noise is typically created by generating random values, and massaging them in various ways to not be as clumpy. This isn't a great approach for older platforms that don't have a lot of compute horsepower or ram.
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 == Authorship ==
-The novel algorithm described here was created by Mike Saarna. If you're going to cite, please refer to it as "Saarna's Bluing Algorithm".
+The (novel?) algorithm described here was created by Mike Saarna, the author of the article.

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 An alternative approach, is to blue the noise by keeping track of recent values with an exponentially decaying running average, and ensuring that new random numbers aren't near the decaying average...
-  A=RAND ; any masking or range-reduction needs to be done here, or else
+  A=GetRandom() ; any masking or range-reduction needs to be done here, or else
-  B=RAND ; it will reintroduce clumpiness into the value distribution
+  B=GetRandom() ; it will reintroduce clumpiness into the value distribution
-  if ABS(B-C) > ABS(A-C) then A=B
+  if Absolute(B-C) > Absolute(A-C) then A=B
   C=(C+A)/2 ; exponentially decaying running average
   ; "A" is holding your next bluish noise value

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 The algorithm creates the blue noise characteristic +3 dB per octave power increase, and it works equally well with LFSR noise sources.
-The algorithm could be modified to produce bluer noise by adding more random values into the comparison. The algorithm as presented produces noise that is strikingly blue, as can be seen in the following Spectrum Analysis section, so additional random number steps are probably not worth the additional effort for most applications.
+The algorithm could be modified to produce bluer noise by adding more random values into the comparison. The algorithm as presented produces noise that is strikingly blue, as can be seen in the following Spectral Analysis section, so additional random number steps are probably not worth the additional effort for most applications.
-== Spectrum Analysis ==
+== Spectral Analysis ==
 <gallery widths=800px>
 File:Spectrum_bbblue.png|Spectral Analysis of a 16-bit LFSR after application of the bluing algorithm.
 File:Spectrum_bb16.png|Spectral Analysis of a 16-bit LFSR without application of the bluing algorithm.
 </gallery>
 == Authorship ==
+The novel algorithm described here was created by Mike Saarna. If you're going to cite, please refer to it as "Saarna's Bluing Algorithm".

← Older revision		Revision as of 16:54, 23 May 2024
Line 26:		Line 26:
	== Authorship ==		== Authorship ==

−	The novel Bluish ~~Noise technique~~ described here was created by Mike Saarna. If you're going to cite, please refer to it as "Saarna's Bluing Algorithm".	+	The novel Bluish described here was created by Mike Saarna. If you're going to cite, please refer to it as "Saarna's Bluing Algorithm".

@@ Line 21: / Line 21: @@
 == Spectrum Analysis ==
 <gallery widths=800px>
-File:Spectrum_bbblue.png|Spectrum Analysis of a 16-bit LFSR with bluish processing.
+File:Spectrum_bbblue.png|Spectral Analysis of a 16-bit LFSR after application of the bluing algorithm.
-File:Spectrum_bb16.png|Spectrum Analysis of a 16-bit LFSR without bluish processing.
+File:Spectrum_bb16.png|Spectral Analysis of a 16-bit LFSR without application of the bluing algorithm.
 </gallery>
 == Authorship ==
 The novel Bluish Noise technique described here was created by Mike Saarna. If you're going to cite, please refer to it as "Saarna's Bluing Algorithm".

← Older revision		Revision as of 15:29, 23 May 2024
Line 26:		Line 26:
	== Authorship ==		== Authorship ==

−	The novel Bluish Noise technique described here was created by Mike Saarna.	+	The novel Bluish Noise technique described here was created by Mike Saarna. If you're going to cite, please refer to it as "Saarna's Bluing Algorithm".