How to posterize a photo in Photoshop

How to Posterize A Photo in Photoshop

Add a fast and easy posterize effect to your image with Photoshop to recreate the classic look of posters printed with limited colors of ink. A step-by-step tutorial.

Written by Steve Patterson.

In this tutorial, I show you how to posterize an image in Photoshop. The term posterize means that we limit or reduce the number of colors in the photo to recreate the look of posters that were printed with limited colors of ink.

So instead of a continuous tone image with smooth gradations, posterizing creates abrupt changes from one color, or one brightness level, to the next. This greatly reduces the amount of detail in the image and gives it more of a painted or airbrushed look.

And while the effect may look complicated, once you know the steps, you can go from start to finish in a couple of minutes!

I'll use this image from Adobe Stock.

The image that will be used for the posterize effect.
The original photo.

And here's what the final posterize effect will look like. You'll learn how to customize the effect, including how to adjust the colors and how to limit the effect to just your main subject, as we go along.

A photo posterized in Photoshop
The final posterize effect.

Which Photoshop version do I need?

To add the posterize effect to your entire image, any Photoshop version will work. But for the second part of this tutorial where we select the main subject, you'll want to be using Photoshop 2020 or later for best results. I'm using Photoshop 2022. You can get the latest version of Photoshop here.

Let's get started!

Step 1: Add a Posterize adjustment layer

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We'll start by creating the initial posterize effect. And for that, all we need to do is apply a Posterize image adjustment. But to keep the effect separate from the image itself, we'll apply Posterize as an adjustment layer.

In the Layers panel, the image appears on the Background layer.

Photoshop's Layers panel showing the image on the Background layer.
Photoshop's Layers panel.

Click the New Fill or Adjustment Layer icon at the bottom of the Layers panel.

Clicking the New Fill or Adjustment Layer icon.
Clicking the New Fill or Adjustment Layer icon.

Then choose Posterize from the list.

Adding a Posterize adjustment layer.
Adding a Posterize adjustment layer.

Photoshop adds the Posterize adjustment layer above the image.

The Posterize adjustment layer is added above the image.
The Posterize adjustment layer appears.

And right away, we see the initial posterize effect. We’ll learn why the colors look the way they do, and how to adjust them, next.

The initial posterize effect.
The initial posterize effect.

How the Posterize image adjustment works

Let's quickly look at what's happening with the Posterize adjustment. The controls for the adjustment appear in the Properties panel. And here we have a single slider named Levels set to a default value of 4.

The Levels slider in the Properties panel.
The Levels slider in the Properties panel.

Photoshop's color channels

Levels controls the number of brightness levels in each of Photoshop's three color channels (Red, Green and Blue). If I switch from the Layers panel to the Channels panel, we see the Red, Green and Blue channels, all mixing together to create the colors we see in the image.

With Levels set to 4, we're limiting the image to just 4 shades of red, 4 shades of green and 4 shades of blue, for a total of 64 possible colors (4x4x4).

Photoshop's Channels panel showing the Red, Green and Blue color channels.
The Channels panel showing the Red, Green and Blue color channels.

The lowest setting you can choose for Levels is 2, which gives you just 2 shades each of red, green and blue.

Lowering the number of levels to 2 in the Posterize properties in Photoshop
Lowering the number of levels to 2.

This results in the least amount of detail in the image and the strongest posterize effect.

Photoshop posterize image effect with the number of levels set to 2.
The effect with Levels set to 2.

And if we drag the Levels slider all the way to the right to its maximum value of 255:

Raising the number of levels to 255 in the Posterize properties in Photoshop
Raising the number of levels to 255.

We're essentially turning the Posterize adjustment off and viewing the full color image.

The posterize effect with the number of levels set tp 255.
The posterize effect is less (or not at all) noticeable at higher Levels values.

I'll switch from the Channels panel back to the Layers panel.

Switching back to the Layers panel in Photoshop.
Switching back to the Layers panel.

Finding the value that works best

So lower values produce a much stronger posterize effect. And with most images, a value of between 4 and 10 works well.

The easiest way to find the best value for your image is to click on the current Levels value to highlight it. Then use the Up and Down arrow keys on your keyboard to cycle through the values.

For this image, I think a Levels value of 5 looks best.

Setting the number of levels to 5 in Photoshop's Posterize properties.
Setting the number of levels to 5.

And here's the result.

Photoshop posterize image effect with Levels set to 5.
The posterize effect with Levels set to 5.

Step 2: Change the blend mode to Luminosity (optional)

Notice that we're seeing some weird colors in the image, especially in the skin tones. That's because we're giving Photoshop so few colors to work with. Depending on your image, these colors may be the effect you want since they give us a more authentic posterized look.

But if you would rather bring back the photo's original colors, simply change the blend mode of the Posterize adjustment layer from Normal to Luminosity.

Changing the blend mode of the Posterize adjustment layer to Luminosity.
Changing the blend mode to Luminosity.

The Luminosity blend mode limits the effect to just the brightness values, leaving the original colors alone. It's really a personal preference, but with this image, I think the original colors look better.

If you prefer the more authentic posterize effect, change the blend mode back to Normal.

The same Posterize effect but with the photo's original colors.
The same posterize effect but with the blend mode set to Luminosity.

Step 3: Add a Levels adjustment layer

To gain a bit more control over the effect, add a Levels adjustment layer between the image and the Posterize layer.

In the Layers panel, click on the Background layer to select it.

Selecting the Background layer in Photoshop's Layers panel.
Selecting the Background layer.

Then click the New Fill or Adjustment Layer icon at the bottom:

Clicking the New Fill or Adjustment Layer icon.
Clicking the New Fill or Adjustment Layer icon.

And this time choose Levels.

Adding a Levels adjustment layer.
Adding a Levels adjustment layer.

Photoshop adds the Levels adjustment layer above the image and below the Posterize adjustment.

A Levels adjustment layer is added to the Posterize effect.
The Levels adjustment layer appears between the other two layers.

Step 4: Drag the midtone slider

In the Properties panel, look for the midtone slider below the middle of the histogram.

The midtone slider in the Levels adjustment properties.
The midtone slider.

Then drag the slider left or right. Dragging to the left will push more of the effect into the lighter tones.

Dragging the midtone slider to the left lightens the posterize effect.
Dragging the midtone slider to the left lightens the effect.

And dragging the slider to the right brings out more of the darker tones. You don’t want to drag too far in either direction. The default midtone value is 1. I'll lower it to 0.96 just to add a bit more contrast.

Dragging the midtone slider to the right darkens the posterize effect.
Dragging to the right darkens the effect.

Click the Levels adjustment layer's visibility icon to toggle it on and off and compare the effect with and without the midtone adjustment.

Click the visibility icon to turn an adjustment layer on or off.
Clicking the visibility icon.

Step 5: Group the two adjustment layers

At this point, if you're happy with the posterize effect being applied to the entire image, you can stop here and you're done. But if you want to limit the effect to just your subject, here's how to do it.

First, we need to place our two adjustment layers into a layer group. So in the Layers panel, click on one of the adjustment layers to select it. Then hold the Shift key on your keyboard and click on the other adjustment layer to select them both.

Selecting both adjustment layers.
Selecting both adjustment layers.

With both layers selected, click the Layers panel menu icon:

Clicking the Layers panel menu icon.
Clicking the menu icon.

And choose New Group from Layers.

Choosing New Group from Layers.
Choosing New Group from Layers.

Name the group Posterize and click OK.

Naming the new layer group.
Naming the new layer group.

Back in the Layers panel, the adjustment layers appear inside the new Posterize group. You can twirl the group open or closed by clicking the arrow next to the folder icon.

The two adjustment layers are now grouped together.
The two adjustment layers are now grouped together.

Step 6: Turn off the group and select the image layer

Turn the effect off for the moment, just so we can see our original image, by clicking the group's visibility icon.

Turning the Posterize effect off.
Turning the effect off.

Then click on the image layer to make it active.

Selecting the Background layer.
Selecting the Background layer.

Step 7: Choose Select Subject

We need to select our main subject. And the fastest way is to use Photoshop's Select Subject command.

Go up to the Select menu in the Menu Bar and choose Subject.

Choosing the Select Subject command in Photoshop.
Going to Select > Subject.

Photoshop analyzes the image, and after a few moments, the selection outline appears. Normally we would want to refine the selection, especially around the hair, using Photoshop's Select and Mask workspace. But we don't need a perfect selection for our posterize effect. We just need one that's good enough. And these days, Select Subject does an amazing job.

I'll quickly show you how to clean up any problem areas after we turn our selection into a layer mask, which we'll do next.

The subject is selected thanks to the Select Subject command in Photoshop.
The subject is selected.

Step 8: Select and turn on the Posterize group

With the selection outline in place, click on the Posterize group in the Layers panel to select it. Then click its visibility icon to turn the effect back on.

Selecting and turning on the layer group.
Selecting and turning on the layer group.

Step 9: Add a layer mask to the group

Click the Add Layer Mask icon at the bottom of the Layers panel.

Clicking the Add Layer Mask icon.
Clicking the Add Layer Mask icon.

And Photoshop instantly converts the selection outline into a layer mask, limiting the posterize effect to just our subject.

A posterize image effect in Photoshop, applied only to the subject, not the background.
The posterize effect is now applied only to the subject, not the background.

Step 10: Clean up the layer mask if needed

In the Layers panel, we see the layer mask thumbnail that was added to the group. The white area on the mask was the area we selected and where the effect is visible. The black area was everything outside the selection and where the effect is hidden.

If you hold the Alt key on a PC or the Option key on a Mac and click on the layer mask thumbnail:

Holding Alt (Win) / Option (Mac) and clicking the layer mask thumbnail for the posterize effect.
Holding Alt (Win) / Option (Mac) and clicking the layer mask thumbnail.

You'll see the layer mask itself in the document. And notice just how great of a job Select Subject was able to do, especially with the woman's hair. Hold Alt (Win) / Option (Mac) and click the layer mask thumbnail again to hide the mask and return to the image.

Viewing the layer mask.
Viewing the layer mask.

Paint on the layer mask to add or subtract areas

But if there were any parts of your subject that the Select Subject command missed, or if there are any parts of the background that need to be removed from the effect, just grab the Brush Tool from the toolbar.

Then paint with white on the layer mask to add an area to the effect, or paint with black to remove an area from the effect. Use the left and right bracket keys ( [ and ] ) on your keyboard to adjust the size of your brush as needed.

Paint on the layer mask with the Brush Tool to add or subtract areas from the effect.
Paint on the layer mask to add or subtract areas from the effect.

And there we have it! Check out my Photo Effects section for more tutorials. And don't forget, all of my tutorials are now available to download as PDFs!