Select roughly 1/2 of the image, starting from the left. You want to capture enough of the "eye" and "nose".
step 2 of 10
Choose Layer > New > Layer via copy from the menu to create a copy of your selection. Select the new layer and choose Select > Transform selection. Right click in the selection and choose Flip Horizontal. Once you have the image transformed, slide it into position on the right hand side of the canvas.
step 3 of 10
Use a large, soft brush in the area indicated to blend the images together.
step 4 of 10
Merge the two layers and then select the upper right quarter of the image. Choose Select > Transform selection, then right click and choose Warp. You don't want both sides of the "head" to be identical, so make some minor alterations - nothing too obvious.
step 5 of 10
In this step, use the Clone tool to build the "mouth". There are a lot of dark areas bordered by branches. Play around with a few using a medium size soft brush until you get something that looks natural.
step 6 of 10
I felt that the sky in this image was too bright. I used the Select > Color Range... tool to collect the white of the clouds and the blue of the sky in a single selection.
step 7 of 10
I then played around some with the Image > Adjustments > Desaturate, and Image > Adjustments > Levels until I got the "right" shade of gray.
step 8 of 10
In this step I returned to the Clone tool and did some minor touch-ups. I removed the background houses and filled in any area that seemed to stand out as identical to the same area on the opposite side.
step 9 of 10
As a final step, I decided to darken the grass in the foreground of the image. I made a selection and copied it to a new layer. Then I made my adjustments using Image > Adjustments > Hue/Saturation until the tone felt right.