What Is Blue Noise?

That's Some Really Lousy Blue Noise! If you're familiar with "white noise," you might be surprised to learn that there's another sort of noise called "blue noise. White noise is random and spreads across all frequencies, much like the static you hear on a TV when there's no signal. However, blue noise is more akin to the soothing waves of the ocean, with its uniform and regular dispersion. If we don't care about the distinction between white and blue noise, why bother learning about it? Okay, so you're making a picture or a video, and you want to make it look like the stars are blinking or the grass is blowing in the breeze. When using white noise, the result will be a monotonous and unnaturally even distribution. However, blue noise produces a more organic, aesthetically beautiful distribution that is random and free of clusters. To that end, how can we make this happen? Dithering is a mathematical procedure used to create blue noise. Dithering is a method of compressing a large number of discrete values into a more manageable range. For blue noise, it transforms the values of white noise into a more structured blue noise distribution. "Spectral Sampling" is the scientific term for this procedure. The process begins with binning the spectrum of frequencies into smaller intervals, from which values are drawn randomly. Using this method, we can guarantee that the values are uniformly distributed across the spectrum, producing the desired blue noise. You could wonder if this doesn't reduce the overall amount of noise's inherent randomness. Yes and no is the ambivalent response. Even if there is more of a pattern to how the noise is distributed, the values within each bin are still completely unpredictable. In that case, why does it have the name "blue noise"? As for why it's called "blue noise," it's because its frequency spectrum looks like a blue band when plotted on a graph. On the other hand, white noise has a flat frequency spectrum that makes it appear white. This type of noise is called "blue" because it is the color of the sky. Instead of the random chaos and unpleasantness of white noise, blue noise provides a sense of calm and tranquility. Dithering and spectral sampling transform the white noise values into a more regulated blue noise distribution. Remember that blue noise is probably to blame the next time you're watching a movie or playing a game and marveling at the gorgeous randomness of the animations.