How to Blur the Edge of an Image in Illustratorby C. Taylor
Blurring the edges of an image de-emphasizes harsh borders and enables the image to better blend into the background. Adobe Illustrator CS6 accomplishes this effect with either the Outer Glow or Feather feature. Because the Outer Glow effect uses a defined color, it is more effective on images that have a relatively uniform color on the edges. Conversely, the Feather effect doesn't use a defined color. Instead, it simply feathers the existing colors around the edge.
Blurring Outward With an Outer Glow
Press "V" to enable the Selection Tool and then click the image.
Access the dominant colors that make up the edges of the image. If you've selected a shape with a solid fill or outline color, reference the color by clicking the "Outline" or "Fill" drop-down arrow, clicking the "Swatch Options" icon and noting the percentages in the C, M, Y and K fields. If the image has an outline color, assess the outline color, rather than the fill color.
Click "Effect," "Stylize" and then "Outer Glow."
Click the "Mode" drop-down menu and select "Normal."
Click the square "Color" icon, enter the percentage values you noted earlier in the appropriate fields and click "OK." Alternatively, click a color in the color swatch and then click "OK." For bright photographs, using white is effective, but for dark photographs, use black.
Check the "Preview" option to get a live view of any changes you make.
Increase or decrease the "Opacity" option according to your preference. Lowering this value enables background images to better bleed through the edge. Increasing this value enables the edge to dominate the background.
Increase or decrease the "Blur" option to change how far, in pixels, the Outer Glow effect extends past the image edge. You might need to experiment to achieve optimal results.
Click "OK" to blur the edges.
Blurring Inward With Feathering
Press "V" and click the image to select it.
Click "Effect," "Stylize" and then "Feather."
Check the "Preview" option to see changes as you make them.
Click the "Radius" arrows to change the point measurement, which defines how far the feathering extends into the image from the edge. Alternatively, type a value in the field and press "Enter" to see the preview. You might need to experiment for optimal results.
Click "OK" to feather the edges inward.