Summary: Learn how a layer mask, one of Photoshop's filter and a simple repeating pattern can easily turn a photo into a pattern of colored dots!

Written by Steve Patterson
Exclusively for Photoshop Essentials.com.

Part of our complete collection of Photo Effects tutorials.

In this Photoshop tutorial, we'll learn how to turn a photo into a pattern of colored dots using one of Photoshop's filters, a layer mask and a simple repeating pattern we'll be creating from scratch. I'll be using Photoshop CS5 throughout the tutorial but any recent version will work.

Here's the image I'll be starting with:

And here's what it will look like when we're done:

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Let's get started!

Step 1: Duplicate The Background Layer

With the photo newly opened in Photoshop, if we look in the Layers panel, we see that we currently have one layer - the Background layer - which is the layer our image is sitting on:

Click on the Background layer and, with your mouse button held down, drag the layer down onto the New Layer icon at the bottom of the Layers panel (it's the icon directly to the left of the Trash Bin):

Release your mouse button when the hand cursor is over the New Layer icon. This makes a copy of the Background layer which Photoshop places above the original:

Step 2: Add A New Blank Layer Between The Two Existing Layers

Hold down your Ctrl (Win) / Command (Mac) key and click on the New Layer icon at the bottom of the Layers panel (the same icon we used in the previous step):

This adds a new blank layer to the document. Normally, Photoshop places new layers above the layer that's currently selected (which in our case was the Background copy layer), but by holding down the Ctrl (Win) / Command (Mac) key while clicking the New Layer icon, we told Photoshop to place the new layer below it instead. We can see in the Layers panel that we now have a new blank layer named Layer 1 sitting between the Background and Background copy layers:

Step 3: Fill The New Layer With Black

Let's fill the new layer with black which will become the background color for the effect. Go up to the Edit menu in the Menu Bar along the top of the screen and choose Fill:

This opens Photoshop's Fill dialog box. Change the Use option at the top of the dialog box to Black:

Click OK when you're done to close out of the dialog box. Nothing will seem to have happened in the document window because the image on the Background copy layer is currently blocking Layer 1 from view, but we can see in Layer 1's preview thumbnail in the Layers panel that we've filled the layer with solid black:

Step 4: Select The Background Copy Layer

Click on the Background copy layer in the Layers panel to select it and make it the active layer:

Step 5: Apply The Mosaic Filter

Go up to the Filter menu at the top of the screen, choose Pixelate, then choose Mosaic:

The Mosaic filter pixelates an image by turning it into a series of solid-colored squares. We can set the size of the squares using the Cell Size option at the bottom of the filter's dialog box. Larger values will create larger squares. Smaller values, smaller squares. These squares will eventually become our colored dots, so you'll want to set your Cell Size value based on the number and size of the colored dots you want in your final effect. This may take a bit of trial and error to get things right. I'm going to set my Cell Size value to 20. Make sure you remember the exact value you used because we'll need it again in a moment:

Click OK to close out of the dialog box. Your image should now look pixelated: