Pixels are the building blocks that make up all digital images. Each pixel contains information about hue, saturation, and brightness, and when they are stacked into neat and orderly grids, it’s possible to recreate almost anything that the human eye can perceive.
While the current technology trend is leading towards high-resolution screens that have pixels so small they cannot be seen, there are plenty of reasons why you might want to highlight the pixelated nature of an image.
Many Photoshop users hope to hide a person’s identity or hide personal information using pixelation, but this can be risky (more on that later).
Of course, it’s not always about concealing image data. An entire genre of pixel art has even been created to pay homage to the design influences of early 8-bit video game systems, which helped to give rise to another technology-inspired genre: glitch art.
Pixelating an image in Photoshop is actually a fairly simple process with just a couple of steps. However, there are multiple different methods that can also create a pixelation effect, so we’ll take a look at some of those options too.
Table of Contents
The Quick Guide to Pixelating an Image in Photoshop
This is a very quick process, with only two steps!
Step 1: Open the Filter menu, select the Pixelate submenu, and click Mosaic.
Step 2: Adjust the Cell Size setting to create the desired degree of pixelation and click OK.
That’s all there is to it, you’ve just successfully pixelated an image in Photoshop! Typically in these guides, I’ll follow up with a more detailed explanation of the process, but there isn’t really anything else to explain.
Instead, I’ll explain how to pixelate a specific part of your image as well as a few other pixelation options that might work better than the Mosaic filter.
Pixelating Specific Areas of an Image in Photoshop
If you don’t want to pixelate your entire image, you can control the way pixelation is applied in two different ways: using a selection or using a duplicated layer with a layer mask.
Using a selection is the simplest and fastest method, but it’s not really ‘best practice’, and those habits are worth forming. If you don’t care and you’re in a hurry, you can simply use one of the selection tools to create a selection, and then apply the Mosaic filter.
To follow the best practice method, start by duplicating the image layer that you want to pixelate. Remember to give it a descriptive name! Make sure that the newly duplicated layer is selected in the Layers panel, then apply the Mosaic filter with your chosen Cell Size setting.
Once you’ve pixelated the whole layer, add a layer mask by clicking the Add Layer Mask button along the bottom of the Layers panel (shown above).
Once you’ve added a layer mask, click the new thumbnail in the Layers panel to select it, and then press Command + I (use Ctrl + I on a Windows PC) to invert the mask. With the mask filled with black pixels, it will be completely transparent, hiding the pixelation effect.
Switch to the Brush tool, and set the foreground color to white. Anywhere you paint white pixels onto the layer mask will make the pixelation effect visible, allowing you the ultimate level of control over how your final image looks.
I don’t recommend using the selection method, but I have to admit that sometimes you don’t need to take the time to follow the best practice method. You’ll have to be the judge of when it’s safe to cut corners!
Alternative Methods for Pixelating Images
This pixelation process is actually simple enough that there isn’t much additional info to add for a more detailed guide, but there are a couple of different methods that can also produce pixelated effects.
Fortunately, they’re almost as simple as using the Mosaic filter, and in some cases, they’re even faster since they have no customization options.
This filter is designed to recreate the halftone dot pattern that was commonly used in early color printing processes and is still sometimes used today. It’s often used to create a mid-20th century printing vibe, but its cultural relevance might be fading a bit.
This filter works in a similar way to the Mosaic filter, but instead of creating perfect squares, it creates random polygonal shapes. This creates an effect similar to a frosted glass window, or perhaps even a stained glass window.
Pointillism is actually a popular but time-consuming art technique from before the days of pixels, though it uses the same principle. Instead of sticking to an orderly grid of dots, the artist uses a series of dots laid out in a more organic series.
The Pointillize filter doesn’t always produce successful results, but it might be worth experimenting with, depending on your image. You’ll usually get better results with very small cell sizes. You can always undo the effect if it doesn’t turn out well!
Security Alert: Beware Of De-Pixelation
If you’re using pixelation to obscure a person’s face or sensitive personal information within a photograph, it’s important to be aware of the fact that it is sometimes possible to undo the pixelation effect and reveal the original image contents.
This isn’t always possible, and the effect usually can’t be completely removed.
But because Photoshop uses a standard and well-known mathematical method of calculating the pixelation effect, it’s sometimes possible to reduce the degree of pixelation by performing the calculations in reverse.
It’s more effective for text-based information since the shapes of each letter are relatively standardized.
This is different from the structure of a pixelated face, where multiple different source faces might produce the same pixelation result and prevent de-pixelation. It also depends heavily on the amount of pixelation that has been added.
Either way, if you need to hide or protect sensitive information, it’s better to simply place a solid block of color over top of the section of your image that you wish to hide.
A Final Word
That’s everything there is to know about how to pixelate an image in Photoshop. Just remember that anything one computer can calculate, another might be able to compensate for – so don’t use pixelation as a means of hiding sensitive or private information.
When in doubt, slap a big colored rectangle overtop instead to make sure nobody will be able to uncover your hidden data.
Happy pixelating!About Thomas Boldt