Creating the illusion of selective DOF (tutorial)

One of the problems with digicams is, due to their small optics, there is always a great degree of depth of field.

Sometimes you'd like to have an slr-like effect, where the foreground is in focus and the background is blurred. The easiest approach is to select everything except the subject, and apply some Gaussian blur. The problem is, unless you're very careful, the subject winds up "floating" in a pool of blur.

A more sophisticated approach is to set the foreground color to black, the the background to white, and enter QuickMask (by pressing the letter Q). Now apply a gradient from the bottom of the frame to the top. The image will look like this:

Press Q again, to go back to normal mode, and apply the Gaussian blur. Its effect will progressively increase from the bottom of the frame to the top.

Let's go back a step. There is still some small amount of undesireable blur that's been added to the subject. So before you exit quickmask, use the eraser tool (with the foreground color set to black) to "paint" the subject, and completely shield her from the effect of the blurring filter.

Now when you exit QuickMask and apply the Gaussian blur, you get the following finished product.

Hope this helps you with progressive blurring.