How to Create a Halftone Effect in Adobe Photoshop ?

Open the image in Photoshop.

Right-click the image's menu-bar and select "Duplicate". Click OK when prompted. This will create a second copy of the image.

In the new image, go to Image -> Mode and select Grayscale. Click OK when prompted.

Go to Image -> Mode again and select Bitmap.

When prompted, make sure that you have "Halftone Screen" selected in the Method field . Click OK.

Adjust the field labeled Frequency. Choose any number between 1 and 999 and click OK. Keep doing this until the halftone pattern is the size you want it to be.

Go to Image -> Mode and select Grayscale. When prompted, input 1 and click OK.

In the Layers window, double-click the "Background" layer and select OK. It should now read Layer 0.

Using the Move Tool, drag the halftone image into the original window. You can now close the duplicate window.

In the Layers window, open the first drop-down menu and select Overlay.