80. Smooth a Jagged Selection Edge
Before You Begin
70 About Making Selections
82 Soften the Edge of a Selection
After you've used the Magic Wand tool to select a region from an image, there's a good chance the selection will have a number of pits and bumps. In some circumstances, this might be fine; but suppose that your project requires your clippings not to appear as though they were ripped out of a magazine and rubbed by sandpaper. Photoshop Elements' Smooth command enables you to iron out the boundaries of any selection so that the perimeter appears to flow fluidly and easily from point to point, as though it were drawn by hand.
With this form of smoothing, the Editor uses ordinary geometry to derive a series of simple curves whose paths most closely fit the more irregular pattern of the selection border. It's quite possible that, after smoothing, some portion you might have meant to exclude could end up being included, and other portions you meant to include could end up excluded. That's because the Smooth command actually changes the selection marquee here and there, smoothing out jagged ins and outs. The purpose of this kind of smoothing is not to create precise selection areas but more general onesareas that appear more naturally cut out, especially when pasted into another image.
Although feathering, anti-aliasing, and smoothing might appear to be synonymous, each actually refers to a different concept. Feathering a selection's border (covered in 82 Soften the Edge of a Selection) enables pixels along the very rim to be partly selected, for a fuzzy border. This involves adjustments being made to these pixels' opacity. Anti-aliasing adjusts the color value of pixels along the bordernot their opacityto help a selection look less jagged along the edges. Smoothing adjusts the geometry of the line used to select a region, removing stair-steps and pockets. This affects the selection's shape.
Make Initial Selection
Open the image you want to work with in the Editor in Standard Edit mode and save it in Photoshop (*.psd) format. In the Layers palette, choose the layer that contains the data you want to select and then use any selection tool to make the initial selection in the image.
To include the stray pixels around the current selection, choose Select, Modify, Smooth from the menu bar. The Smooth Selection dialog box displays.
Set Sample Radius
In the Sample Radius field, specify a number between 1 and 100 that indicates the maximum number of pixels that the Editor will add or subtract on either side of the existing selection border to smooth out any jagged ins and outs it finds. This number represents how much change you'll allow to the existing selection perimeter. With a high value, your selected region could conceivably become much smaller. On the other hand, pockets of unselected pixels in the original region could become selected when smoothed because the Smooth command doesn't look just outside a selection for similar pixels, but inside as well. Click OK to proceed.
Because higher-resolution images have pixels that are closer together (more dense), you might have to set the Sample Radius value higher than you would in a lower-resolution image to get the same result.
View the Result
After you're satisfied with the selection, make changes to the area within the selection, copy or cut its data to another image or layer, or delete the data within the selection. Save the PSD image and then resave the file in JPEG or TIFF format, leaving your PSD image with its layers (if any) intact so that you can return at a later time and make different adjustments if you want.
In this example, I used the Magnetic Lasso to select an old tractor I had seen at our state fair. I planned on using the tractor in a calendar for my brother, who's a big fan of old farm equipment. The Magnetic Lasso did a pretty good job, but the curves on the tractor wheels were still too jaggedy! A quick smoothing rounded out those curves easily.