Clipping with the magic wand tool has the advantage of being fast but the disadvantage to not leave the field clean behind him. Indeed many undesirable residual pixels populate your photo.

We're going to see below how to properly complete the job when using the magic wand tool.

Start from a landscape photo, the project is to remove the sky to keep only the foreground grass and the tree, the difficulty of this project will be to remove the sky itself also inside the tree.

Save the photo in psd photoshop format.

Right click on the layer 'background', select 'Duplicate Layer ...' Name this new layer as desired.
In the exemple I called it 'paysage' landscape in French.

Uncheck the eye beside the layer 'background' and select 'paysage' layer.

Select the magic wand tool, set the 'Tolerance' to 40, 'Contiguous' checked.

Click to select sky areas, then press 'Del' to delete those areas.
Repeat several times that operation until the sky looks clean.

The checkerboard representing the transparency gradually appears.
I could remove more items with the magic wand, but I have not removed everything to better illustrate my example.

Select the layer 'background' and then create a new layer by clicking the icon at the bottom right of the 'Layers' palette.

Name the new layer as desired, in my example, I named it 'black_background'.

Select the paint bucket tool, select black as the foreground color.
Click on the image to darken the layer 'black_background'.

Below is the result.

You can see that the sky is intimately nested into the tree and we will have to work the pixels one by one to eliminate it inside the tree.

Select the 'Eraser' tool and set its thickness to 1 or 2 pixels depending the area where you're going to work.

Select the 'paysage' layer.

Zoom on the image to work comfortably, when working with similar magnification you must regulary return to the full picture in order to have a good a good idea from the whole project.

Below, remaining sky pixels, erase it.

After a little working time you should have the result below.

'black_background' layer is no longer required, delete it by selecting it and clicking the 'delete layer' icon at the right bottom right of the 'Layers' palette.

The image is now ready to be used in a transparent PNG format or we can, as we shall see later in this tutorial, create a sky from scratch quickly and easily.

Select the 'gradient' tool 'and in the settings of this tool, open the drop-down list to choose the gradient (top red arrow in the illustration below) and select the next picture gradient.

Choose this gradient and click on it to open the gradient dialog box.

In the dialog box, click the little brown cones and pull them down to remove it, keep only the extremities cones, the left blue and the right one.

You can change the gradient by moving blue and white cones but also by moving the central diamond. To allow you to reproduce the blue color, its hexadecimal code is # 3399cc.

Create a 'sky' layer.

Select the 'gradient' tool and apply it to your image, from bottom to top by holding down the 'Shift' key to draw a perfect vertical line with your gradient tool.

Below is the result with an artificial sky, perfect to spread a message for example.

Enjoy

Patrick