Turn any photo into a dot grid artwork with these Photoshop actions. You'll get great results with dots that change size. They get larger in brighter areas and smaller in darker areas. Free download available.
Choose Black & White. If you don't have Black & White or if you're using Photoshop CS2 or older, select Hue/Saturation instead.
The Black and White tool will appear. Simply click OK with the default settings. If you are using Photoshop CS2 or older and added a Hue/Saturation adjustment layer instead, simply reduce the saturation to -100 and click OK.
Step 3: Blend the layer
Now that we have the adjustment layer, we'll need to make it blend into the image to restore the color. For this, we can simply change the blending mode to Overlay. In the Layers palette, click on the drop down menu and select Overlay.
Now your image should have a nice harsh lighting effect.