We often wish to blur the background of a subject to add a sense of depth or to simulate 'depth of field'. The simple ploy of copying the layer, blurring the one beneath, then using a layer mask on the upper layer to reveal the blurred background can, however, cause an unwanted blurry 'halo' around the subject.  There is a better way.

First of all let's look at the problem.
The example shows the result of adopting the simple method described above.  The blurry 'halo' can clearly be seen.

Click 'Continued' below to learn about the superior method...........