Paint Shop Pro Clinic Tutorial
August 22, 2002

Whether or Not to Anti Alias or Feather a Selection
on the Tools Option Palette before Making the Selection

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Or why I almost never do. :)

First let's look at the differences when we make a simple rectangular selection and copy and paste it onto another image.

You will need two images for this exercise.

Right click on Cactus.jpg on the left, save the image to your hard drive.

Right click gradient.jpg on the left and save to your hard drive.

Open both Cactus.jpg and Gradient.jpg in Paint Shop Pro 7.

Pick the rectangular selection tool.

On the Tool Options Palette, set the Selection type to Square by clicking the down facing arrow next to the type box.

Make sure feather is set to 0 and Anti alias is UNchecked.

In the Cactus image drag out a square approximately 100 x 100 pixels.

Right click on the Cactus image's title bar and choose Copy from the fly out box.

Right click on the Gradient image's title bar and pick Paste as new layer.

Notice how crisp and sharp the edges are on the pasted image.

On the Cactus image again, pick the rectangular selection tool.

Check Anti alias on the Tool Options palette.

Drag out another 100 X 100 pixel Selection. Copy and paste onto the gradient image as a new layer using the method described above.

Notice the difference in the edges between the Antialiased (bottom) and non antialiased (top) ones. (10:1) zoom

Antialiasing makes a smooth-edged selection by making the pixels along the edge semi-transparent. If antialiasing is not applied, the edges of a selection can look jagged, especially in freeform selections. Antialiasing is useful when combining images or making a text selection. Think of it as a baby or one pixel feather.
Back on the Cactus image, set the Tool Options for the Rectangular selection tool by UN Checking Anti alias and setting the Feather to 5 pixels.

Drag out another square selection and copy and paste it as a new layer to the Gradient image.

Compare the edges again.

Notice in the image above on the right side, how the pixels gradually go from fully opaque to totally transparent over the 5 pixel feathered edge.

From the PSP Help Files

"Feathering controls the sharpness of a selection’s edges. By fading a set width (in pixels) along the edges, it produces a smooth transition between a selection and the surrounding area. The feathering value is the width of the transition area in pixels. A higher feathering value creates softer edges by feathering more pixels. Feathering is useful when pasting a selection. The fading helps the selection blend into the background and appear more natural."

Are you wondering why I don't like using feathered and antialiased selection very often if it does such a nice job?

Let's look at it this way... For regular selections such as squares and rectangles, ovals and circles, it's great.

BUT.. for free hand selections where we want to select a precise area of an image, look at what happens.

In the cactus image, pick the Freehand Selection tool. Pick the Point to Point option then set the Feather to 5 pixels.

Make a careful selection around a few of the cactus fruits in the image and a piece of the pad. Be sure to mess up the selection a little bit by going outside the fruit a bit.

Double click to set the selection.

Notice how the selection jumps outward 5 pixels.

Suppose we want to use the freehand selection tool with the CTRL or SHIFT key to subtract or add to our selection to make it more accurate?

Accurately adding to or subtracting from this feathered selection is virtually impossible when the tool is set to feather. How can you tell where you screwed up?

Copy and paste the selection to the gradient image as a new layer.

A bunch of green pixels surrounds the fruit fading to transparent, but did we want those green pixels at all? I didn't!

To fix this up, you could use the eraser tool and erase the feathered edge and do a bunch of extra work.

BUT here are my more accurate and efficient ways to accurately select then soften the selection.

In the cactus image, with the Freehand selection tool, set the feather to zero and UN Check the anti alias on the Tool Options palette.

Use the Point to point type and surround a few cactus fruits and some of the pad.

Double clicking sets the selection exactly around the areas we selected.

Now if you need to "fix" the selection using the CTRL or SHIFT keys to subtract from or add to the selection, it will be very accurate.

Copy and paste this area onto gradient image as a new layer.

As you can see in the screen shot, the edges are very hard and jaggy.

So yeah, you understand the accuracy part of not using an antialiased or feathered selection originally but how to soften this selection?

Two ways:..

First Way:

On the Cactus image, with the selection still in place as you want it, all fixed and set to go.

Go to Selections >
Modify > Contract and put in 1 pixel.

Then do a Selections > Modify > Feather and put in 1 pixel.

Copy and paste this as a new layer on the gradient image.

Notice, even at 4:1 zoom, how the edges are slightly transparent, making the image less jaggy.

Second Way:

On the gradient image, pick the layer containing the jaggy, unaltered parts of the cactus. Highlight its name on the layer palette.

Use the magic wand tool set to RGB Value and 20 for tolerance and 0 for feather and click in the blank area outside the the cactus pad itself to select the background.

Then do an Selection > Invert from the Menu bar.

The selection snaps tightly around all the opaque pixels in the layer.

Do the same as before, from the Menu Bar, Selection > Modify > Contract 1 Pixel and Selection > Modify > Feather 1 pixel.

From the Menu Bar, Selection > Invert

Press the Delete Key on the keyboard.

Note that the result is identical to the layer where the modifications were applied on the cactus image then copied and pasted.
OK, you say, I see why the geekie Khiba made the original selection without any feather or antialiasing, because its more controllable and accurate but why would she use the second method to soften the edges when it takes more steps?

Good question... Since both methods yield the same results...

Its a control issue again. Also one of visibility. Is much easier to "see" edge detail away from the original background that matches so perfectly. ;)

But either way is fine!

ReCap:

Making a Freehand selection without Feather and without Anti alias is pixel accurate and easy to modify. . Contracting the selection after making it gives you precise control of how many pixels you need to go in to clean up the edges.

Feathering gives you precise control over how soft the edges should be.

On regular selections such as Square, Rectangle, Oval, using anti alias or feather is fine as long as remember that the feather is added to the outside of the selection!

Wicked Wanda, the Magic Wand tool behaves similarly to the freehand selection tool but is unpredictable. Play with it and you will see what I mean. I almost never use feather with the wand prior too making the actual selection.

Hope this helps some...

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