Noise Filters
Value noise can also be the basis for many textures, by applying additional filters. A nice brushed metal texture can be achieved by applying a motion blur filter to value noise. Even fractal noise is based on multiple iterations of value noise. |
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Color noise adds random values to the red, green, and blue channels of the buffer. Small amounts of color noise can actually improve the look on many images. Banding can occur on images with smooth color blends and gradients, and roughing them up a little bit with noise can actually make them look smoother an more natural instead of computer generated. |
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Jitter noise roughens an image by displacing pixels by random values. |
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The Samples parameter controls how many samples will be taken from the surrounding pixels. The Scatter modes sample from a pixels color. In the case of RGB, HSV, and YUV modes, the samples are taken randomly from each channel of the color model independantly. |
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You can adjust the color of the grain, as well as the scale. |
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Since our eyes are more sensitive to grain in areas of low detail, it is helpful to remove grain there, and leave it in the higher detail areas. The Mode drop-down control should be kept on the “Threshold box filter” mode for all practical purposes. Note, digital cameras will often perform their own noise reduction. |
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