Blurring backgrounds

What is the best method in PS for blurring the busy background activity behind a prominent subject without leaving a telltale dividing line? I have recently taken a number of nice bird images in my yard but many have distracting bare bush branches behind them.

oh my!  this is such NOT an easy answer.  

I'm going to tackle this from two perspectives.  one will or may help now and one may help avoid a lot of the work in future images.  Here goes.


1.  future.   in many aspects of life, the best way to deal with objections, is to avoid them in the first place:  (aka , anticipate and deal with before the subject is raised)..  Objections here, being details in the bg.  feeders and perch need to be in that sweet spot so the bg is totally oof.  ( feeder far enough away to satisfy that criteria).  Not meant as patronising.  benefit to those that are looking on the internet and may not have thought of.  

2.  your current question.  the key point I am picking up is not leaving a tell tale dividing line.  I can relate to that as the best PS work should be not easily identifiable.  I can only say that irrespective of whether you use gaussian blur or noise reduction, a), much is dependent on the file size you are showing and b), the following zooming you are prepared to do to correct the "dividing line".  

I'd personally do a youtube to see what others are doing.  I'm not personally comfortable with what extents some people may go to as there are many options.  My experience is limited to showing a 1024px image which I've zoomed in on to cover those zones in the past when using Canon; but personally haven't needn't to for some time.  (for the internet I'll use NR and then zoom in on the same way I'd get rid off over sharpening on the edges.   For normal work, I just don't bother.  

Regarding those image you already have,  I guess you may need to view at 100% and correct any edges after applying what version of diffusion for the bg.

i appreciate you may have been looking for an easy answer, which might yet come... ( I use..... works a treat)...  but after 47 views before my reply, i am guessing there may not be that easy answer.  

(i know much about wildlife, tracking, etc, and enjoy it immensely... my PS knowledge is adequate but cannot leave a colleague un-answered out of respect.  ultimately, there may be other forums that can answer better.  )

To add to what David wrote, the lens blur filter, when used properly gives a more natural look than Gaussian blur and you can sort of match the grain of the background which you can't do with Gaussian blur.

Do a composite:

Extract the bird (and anything else you want sharp) --- > Blur the photograph --- > Put the bird (and everything else extracted) back in.

Not easy. But I haven't seen any better way.

This is a method that is a little tedious but not bad....

1. create a duplicate layer of your image
2. blur the duplicate layer (be careful here not to go too far here or your subject will look as if it's been "cut out" of the image when you're done)
3. to the duplicate add a "reveal all" layer mask
4. with a black paint brush you can now "paint in" the bird and it's perch on the layer mask and the sharp layer underneath will be revealed, you have to magnify the image and use a small brush on the edges.

Topaz Remask is worth a look. It is a great selection tool to isolate the bird from the background. Duplicate and blur the background and place the extracted bird back on top.

I will typically blur a duplicate layer, add a layer mask and then use the gradient filter to create a nice gradual transition.