You will need
  • - Photoshop;
  • - the image to be processed.
Open the image of the subject on which it is necessary to add a shadow in Photoshop using Ctrl+O or Open command ("Open") the File menu ("File").
Select the object that will cast a shadow. To do this, select in the palette "Tools" Polygonal Lasso tool (Polygon lasso). Click with the left mouse button on any point on the contour of the figure casting the shadow. Route selection on a straight section of the circuit and again click the left mouse button in the place where the circuit is bent. In this way, highlight the entire figure. Lock the selection by clicking the point where you began to distinguish the outline.
Create a new layer by clicking the Create new layer (Create new layer"), which is located at the bottom of the palette "Layers". The same result you get using the New command ("New") in the menu Layer ("Layer").
Fill the selection with black color. In order to do this, select the Paint Bucket tool (Fill) in the palette "Tools". Click on the colored square at the bottom of the palette "Tools". In the palette, select black color and click OK. Click the left mouse button inside the selection. The resulting figure will serve as the basis for the shade.
Remove the shade selection command Deselect from the menu Select.
Transform the shadow. To do this, use the command in the Distort group Transform from the Edit menu. Dragging with the mouse the corners of the frame around the figure, place the figure in the projection, which must be a shadow from the selected object. Apply the transformation by pressing Enter.
Apply to a layer with a drop shadow Gaussian Blur filter from the group Blur Filter menu. A blur radius set depending on the nature of light in the image: a strong light source at a close distance from the subject will give a shadow with sharp edges, and accordingly, the blur radius you need to choose smaller. The scattered light is pretty blurry shadows. On average, blur the shadow enough values of two to three pixels. Click on the OK button.
Change the blend mode of the shadow layer from Normal to Multiply. To do this, click the right mouse button on the layer with the shadow and select Blending Options from the context menu. In the opened window, select Multiply from the drop-down list.
Increase the transparency of the shadow layer. To do this, click on the arrow to the right of the word Opacity in the layers palette and drag the slider to the left to a value of 50%.
If any parts of the shadow are superimposed on the object that should cast a shadow, remove them using the Eraser Tool (Eraser).
Save the image using Save or Save As, which is located in the File menu.