Older dot matrix printers created text and images by printing a series of dots of different tones to create the image. While newer printers are capable of much higher resolution, you may wish to create the classic dot matrix effect on your photos to achieve a retro look. You can do this by using the halftone filter on Adobe Photoshop. Combine the original photo with a layer composed of halftone dots, and you will achieve the classic dot matrix effect.
Open your photo with Photoshop.
Click on the Layer menu and choose "Duplicate Layer."
Click on the Image menu, choose "Adjustments," "Black and White."
Click on the Filter menu. Select "Sketch," "Halftone Pattern."
Adjust the "Size" slider to get the desired dot size. Adjust the "Contrast" slider until the dots are separated and distinct.
Find the "Opacity" slider in the "Layers" panel. Adjust the opacity down to about 30 per cent. This will allow the original layer to be seen through the dot matrix filtered layer you just created, making it seem as if the original photo has been printed in dot matrix style.