Technique One: Add a Layer Mask
Technique Two: Use a Vector Shape as the Mask
The great thing about working with a vector is you can use or create any vector shape and then apply it as a mask for the image.
Smooth: This slider makes the edge transition less sharp.Feather: Moving this in or out increases or decrease the fade at the edges of the mask.Contrast: Moving this slider makes the edge of the selection sharper and more defined.Shift Edge: Sliding this in or out increases or decreases the diameter of the selection area you set in Step 2.
The neat thing about vectors in Photoshop is that they can be edited. To edit the shape of the mask, select the mask in the Layers panel and switch to the Path Selection tool. You can drag points out or add points using the Pen tool.
Helpful Tips
Paint in the layer mask with shades of gray to adjust the overall effect. Just click the mask thumbnail in the Layers palette to activate it for painting. Default the foreground and background colors to black and white and select the Brush tool and—with the mask layer selected—paint over the mask area. Be careful with this technique, given the old adage that “black hides and white reveals.” The shades of gray between them control opacity. If you decide you don’t like the effect, drag the mask thumbnail to the trash icon on the Layers palette and choose Discard. To reposition the vignette, click the link icon between the layer thumbnail and the mask thumbnail to move the mask independently of the layer. Don’t forget to relink them when you’re done. You don’t have to use just the Elliptical Marquee tool. The Rectangular Marquee or text can be used as a mask in Photoshop, too.