How to Add Gaussian Blur to a Photo in Photoshop CS5
The Gaussian blur filter can add a smoothing effect to an image, blurring out overly sharp edges and, if the blur is set to a high enough level, turning a photograph into a glowing, dreamy composition. It can also be used to mimic the shallow depth-of-field seen on portrait photographs taken with a wide aperture. The Gaussian blur filter can be applied to either a selection within the image or an entire layer.
Click on the layer that you wish to apply the Gaussian blur filter to in the layer panels window.
Select an area of the image using the selection, magic wand or lasso tool. If you are applying the Gaussian blur to the entire layer, leave the image area unselected.
Click “Filter,” click “Blur” and click “Gaussian Blur…” from the sub-menu.
Move the slider left or right to decrease or increase the blur effect. You can also input a value into the “Radius” box to control the blur effect. Preview the blurred image in the main image window, or use the preview box in the “Gaussian Blur” dialog to see a zoomed-in preview of the image.
Click “OK” when you are satisfied with the image.