Removing Noise (Speckles) with Paint Shop Pro 8
Removing noise from an image sounds a bit illogical, like subtracting apples from oranges or removing odor from a TV program. Okay, you can perhaps imagine ways to do the latter, but apply that same imagination to how your TV looks when you run a vacuum cleaner: The screen is covered with speckles. That's graphical noise: pixels altered at random locations and in random colors.
The trick with removing speckles is to avoid removing freckles — and other speckly stuff that's supposed to be in the picture. (Unless, of course, you want to get rid of the freckles!) For that reason, Paint Shop Pro offers several choices, depending on what you need. Choose Adjust --> Add/Remove Noise and then one of these menu selections:
- Despeckle: Removes smaller, isolated speckles altogether. Good for removing a light coating of dust. Speckles that are closer to each other tend to form clumps, however.
- Edge-Preserving Smooth: Gives an effect like rubbing carefully within the shaded areas of a pastel drawing, using your finger. Speckles disappear into a uniform shade, and you keep the sharp edges of those larger areas. This effect is also good for removing the random discoloration of pixels that often results from shooting digital photos in low light. In the adjustment dialog box that appears, drag the Number of Steps slider to the right to make a smoother image.
- Edge-Preserving Smooth, turned up high, creates a nice oil-painting-like effect on photos!
- Median Filter: Removes speckles by removing fine detail, a kind of blurring process in which each pixel is recalculated to be the average of its neighbors. Contrast is lost at the detail level. An adjustment dialog box appears in which you drag the Amount of Correction slider to the right to remove increasingly large details.
- Salt-and-Pepper Filter: Removes speckles of a particular size (or up to a particular size) you choose. A Salt-and-Pepper Filter adjustment dialog box appears, with these adjustments:
• Speck Size: Adjust this value to match or slightly exceed the size of the speckles you're trying to get rid of. (You may have to zoom in close to figure out how big your speckles are.)
• Sensitivity to Specks: If the right preview window shows clusters of specks remaining, increase this value. Too high a value blurs your photo.
• Include All Lower Speck Sizes: Enable this check box to remove specks of Speck Size and smaller. Otherwise, you just remove specks close to Speck Size.
• Aggressive Action: Enable this check box to remove specks more completely. Otherwise, you may simply reduce the specks' intensity.
- Texture-Preserving Smooth: This effect sounds like a sophisticated grade of peanut butter. Actually, it blurs and reduces the contrast of tiny specks while preserving the larger variations that give texture to grass, wood, water, and the like. The result is sort of like a crunchy peanut butter without small, gritty chunks. An adjustment dialog box appears in which you adjust the Amount of Correction value upward to minimize specks.
- Add Noise: Why would you want to add noise? If you're trying to make a photo look older or give it a rusty patina or an overlay of static, you can seed your image with random pixels. Drag the slider to the right to obscure your image in a haze of dots. There are three Add Noise selections, each of which deals with color placement:
• Random: The noise colors are — surprise! — chosen at random from the available color palette. If you have a black-and-white image, don't expect to see red pixels, although you could see garish orange and purple pixels in a mostly green picture.
• Uniform: The noise colors are all chosen from within the image itself, making this option perfect for "olderizing" a picture.
• Gaussian: Choose this option for a more static-like effect.
You can always select an area using the Paint Shop Pro selection tools, in order to add or remove noise from only that specific area.