I need help erasing the background of a photo.

Question

Sometimes I do it just fine and other times I can't get it to magic erase the background to save my neck.
I've spent 4 hours trying to get this done today......earlier I did it to a photo in 5 minutes.
HELP

Answer 1

There's another approach to getting a transparent background -- using the selection brushes, but for a subject with areas of wispy hair you'll definitely need to do some handwork.
Use the Quick Selection brush on the woman, alternating between the "add" and "subtract" modes to get a close approximation.
Switch to the Selection Brush tool to refine the selection.
Use Select...Feather with a setting of 1.7 pixels to soften the edges.
Layer...New...Layer via Copy to copy the woman to a new layer with transparency.
Now the most tedious part -- refining the wisps of hair.  Fortunately, there's only a small area that needs the work:
Zoom in real tight and remove most of the dark areas by clicking on them with the Magic Eraser tool set to Tolerance:  32, Anti-Alias, and Contiguous. 
Use the Background Eraser with a Tolerance of 14% to further remove dark areas internally and at the outer edges. 
Use the Eyedropper to select a light gray hair colour and the Color Replacement Tool to paint over the wisps of hair to remove most of the green colour cast.
Use the Clone tool at a 4pixel size to draw over some areas of the wisps of hair to further remove the green cast.
Use the Smudge tool at about a 7px size to smooth out the tone in the individual wisps.
Now comes the fun part of building the final image:
Add two Color Fill layers beneath the extracted image.
Change the colour of the upper Color Fill layer to a dark, somewhat gray blue.
Change the colour of the lower Color Fill layer to a light, somewhat gray green.
Draw a black-to-white radial gradient on the mask of the upper blue Color Fill layer, starting at the lower left and running to the upper right.
Add a new empty layer immediately below the extracted image.
On that empty layer, use Filter...Render...Clouds.
On that clouds layer, use Filter...Blur...Surface Blur with a Radius:  25px and a Threshold:  25px.
Set the Blend Mode of that clouds layer to "Multiply" and the Opacity to 62%.
Refine and balance the overall effect by using the Eraser tool with a hard edge on the extracted image layer to clean up some of the edges, and use the Blur tool to get rid of any obvious hard edges.
The layers wind up looking like this:
And the final image looks like this:
That clouds layer gives a nice, blurred "semi-natural" looking outdoors effect to the background -- since the lighting on her face is obviously natural sunlight, the background should also seem to be an outdoors background.
Ken