Remove dust and scratch marks from bitmaps
You can quickly improve the appearance of a bitmap by removing dust and scratch marks. The dust and scratch filter works by eliminating the contrast between pixels that exceed the contrast threshold you set. You can set a radius to determine how many pixels are affected by the changes. The settings you choose depend on the size of the blemish and the area surrounding it. For example, to remove a white scratch that is 1 or 2 pixels wide on a dark background, you can set a radius of 2 or 3 pixels and set the contrast threshold higher than you would for a similar scratch on a light background.
To remove dust and scratch marks from a bitmap
• Radius — sets the range of pixels used to produce the effect. To retain image detail, choose a setting as low as possible.
• Threshold — sets the amount of noise reduction. To retain image detail, choose a setting as high as possible.