Step 1. Open the image you want to add the linear light and halftone dot effect too. Step 2. Duplicate the image to a second layer. Label the layers "original image" and "halftone layer". Move the "halftone layer" to the top of the layers window and make sure you have that layer selected. Step 3. Make sure you foreground color is white and your background color is black. With the "halftone layer"