Over on the new flcikr group Foodography - where the theme of Oranges Aren't the Only Fruit is already receiving plenty of good and 'room for improvement' images - one of the questions raised by a photo-newbie was how to blur a background once the image has been taken. Now I am no Photoshop expert but this is how I do it.

 

I have selected this image, not because it is particularly good or anything, but just as a demonstration. The background is too distracting but the straight edges of the crisps give a clear line where we could extract the background and add some blur. As I said this is an introduction piece but if others have a better way to achieve the same effect please feel free to comment. (I use Photoshop 7 on Windows XP).

Step 1 - create a duplicate image layer.

Step 2 - highlight this layer (Background Copy) and select Filter/Extract or ALT Ctrl X

Step 3 - I find making the image larger easier to work with so on the Extract screen expand the image to a suitable size (click the magnifier).

Step 4 - select the pen tool (very top left) and click the Smart Highlighting box on the right. The Extraction smoothness I leave at 0. (Is that right?)

Step 5 - draw around the part of the image you wish to extract. Fill the area by clicking first the paint bucket tool top left and then in the area to extract. Click on OK.

Step 6 - the extract window will close and thebackground layer should have just the extraction. To blur this area select Filer/Blur/Gaussian blur and adjust the layer to the required blurriness. In this instance I selected 2.0.

You could repeat the action on the back packet for example, with a reduced blur, as I have done in the final image. I used a blur of 1.0 here.