Noise Filters

Noise filters will add noise effects to your image, such as monitor noise, film graininess or just pointillistic artistry. This is the place to find such a filter.

Noisify

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Noisify adds random noise to the entire image. If you have used a lot of Sharpen to fix an unfocused photo, you can add a little noise to oversharp areas to make it look more natural.

Note: This filter will not work with indexed images.

Parameters

You can add noise to all of the RGB channels, or to each RGB channel independently. The reference scale goes from 0.00 -- no noise -- to 1.00 -- full noise level.

· Channel 0 is red (or gray in a grayscale image).

· Channel 1 is green (or alpha in a grayscale-alpha image).

· Channel 3 is blue

· Channel 4 is alpha (in an RGB-alpha image).

If the Independent button is checked, each channel will get the noise level you have specified with the sliders. If Independent is unchecked, the same relative noise pattern will be applied to all channels, so that the color balance from the original image is kept intact.

Randomize, Hurl, Pick And Slur

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These plug-ins cause random displacement of pixels in three different ways.

Options

The random displacement can be adjusted to affect 0% to 100% of the pixels. You can also specify if you want the filter to be repeated only once, or up to 100 times.

You can set the randomization seed to generate numbers from the current time so that there will be a new random operation every time you repeat the filter. If you set a value of your own choice in the input field, a given operation will be repeated each time. All three Randomize filters work for all image types. A warning is in place for Hurling, because a too high Randomization or Repeat value will produce solid noise with no trace of the original image.

Randomization Types

· Hurling: Changes a pixel to a random color, if it's within the given range of randomization.

· Picking: Applies the highest channel values picked from three random neighbor pixels to the channels in the chosen pixel.

· Slurring: This is similar to Picking, but this filter will distort your image downward. If a pixel is chosen to be slurred, there's an 80 percent chance that a channel value from the pixel directly above it will be applied; otherwise, a random neighbor above the chosen pixel will be used.

The color variation is usually less in Slurring and Picking than in Hurling because the channel value replacement often results in shades of gray.

Spread

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The Spread plug-in spreads the pixels in your image. It will move a pixel to a random location. However, this location will be in the range of your setting in the slidebars. This makes it possible to spread the image vertically, horizontally or in both directions.

With this filter, the noise effect will not appear in the entire image as with the other noise filters. You will only see it in the border of contrasting areas. Also, because only the colors present in the image will be used, and there is no channel displacement, no new colors will be introduced.