Noise Filters; To Use The Dust And Scratches Filter - Adobe PHOTOSHOP CS2 User Manual

Noise filters

The Noise filters add or remove noise, or pixels with randomly distributed color levels. This helps to blend a selection
into the surrounding pixels. Noise filters can create unusual textures or remove problem areas, such as dust and
scratches.
Add Noise Applies random pixels to an image, simulating the effect of shooting pictures on high-speed film. You
can also use the Add Noise filter to reduce banding in feathered selections or graduated fills or to give a more realistic
look to heavily retouched areas. Options for noise distribution include Uniform and Gaussian. Uniform distributes
color values of noise using random numbers between 0 and plus or minus the specified value, creating a subtle effect.
Gaussian distributes color values of noise along a bell-shaped curve, creating a speckled effect. The Monochromatic
option applies the filter to only the tonal elements in the image without changing the colors.
Detects the edges in an image (areas where significant color changes occur) and blurs all of the selection
Despeckle
except those edges. This blurring removes noise while preserving detail.
Dust & Scratches Reduces noise by changing dissimilar pixels. To achieve a balance between sharpening the image
and hiding defects, try various combinations of Radius and Threshold settings. Or apply the filter on selected areas
in the image. See also "To use the Dust And Scratches filter" on page 520.
Reduces noise in an image by blending the brightness of pixels within a selection. The filter searches the
Median
radius of a pixel selection for pixels of similar brightness, discarding pixels that differ too much from adjacent pixels,
and replaces the center pixel with the median brightness value of the searched pixels. This filter is useful for elimi­
nating or reducing the effect of motion on an image.
Reduce Noise (Photoshop only)
image or individual channels.
See also
"Reducing image noise" on page 353

To use the Dust And Scratches filter

Choose Filter > Noise > Dust & Scratches.
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2 If necessary, adjust the preview zoom ratio until the area containing noise is visible.
Drag the Threshold slider left to 0 to turn off the value so that all pixels in the selection or image can be examined.
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The Threshold value determines how dissimilar the pixels should be before they are eliminated.
Note: The Threshold slider gives greater control for values between 0 and 128—the most common range for images—
than for values between 128 and 255.
Drag the Radius slider left or right, or enter a value in the text box from 1 to 16 pixels. The Radius value determines
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the size of the area searched for dissimilar pixels.
Increasing the radius blurs the image. Use the smallest value that eliminates the defects.
Increase the threshold gradually by entering a value or by dragging the slider to the highest possible value that
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eliminates defects.
Reduces noise while preserving edges based on user settings affecting the overall
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User Guide