How to Blur Part of an Image on Mac Without Photoshop

You have a photo or image on your Mac and you need to blur just one part of it — a face, a license plate, an address, a credit card number. You don't have Photoshop and you don't want to pay for it. What are your options?

Good news: there are several ways to blur part of an image on Mac, from free built-in tools to dedicated apps. Here are four methods, starting with the simplest.

Method 1: Cover It with Preview (Free)

macOS Preview doesn't have a blur filter, but you can effectively hide part of an image by covering it with a solid-colored shape.

Steps

1. Open the image in Preview
2. Click the Markup toolbar (pencil icon)
3. Select the rectangle shape tool
4. Draw a rectangle over the area you want to hide
5. Set the fill to a solid color (click the shape, then set fill color)
6. Set the border to "None"
7. Important: Go to File → Export and save as a new PNG or JPG. This flattens the shape into the image permanently.

Limitations

• No actual blur effect — just a colored rectangle
• Looks less polished than a real blur
• Make sure to export the file, not just save. If you save in a format that preserves layers, the shape might be removable

Method 2: Use Pixelmator Pro ($50)

Pixelmator Pro is a professional image editor available on the Mac App Store. It has proper blur tools.

Steps

1. Open the image in Pixelmator Pro
2. Use the selection tool (rectangular, elliptical, or free-form) to select the area you want to blur
3. Go to Format → Blur → Gaussian Blur
4. Adjust the blur radius until the content is unreadable
5. Deselect and export

Limitations

• Costs $50
• Manual process — you have to identify what to blur
• Overkill if all you need is privacy redaction

Method 3: Use Photos App (Free)

The built-in Photos app has basic editing tools that can help, though it's not ideal for targeted blurring.

Steps

1. Import the image into Photos
2. Open it for editing
3. Use the Retouch tool or adjustments to modify the area
4. Export the edited image

Limitations

• The blur/retouch tools are designed for photo retouching, not privacy redaction
• Difficult to precisely blur a specific rectangular area
• Not practical for text redaction

Method 4: Use BlurData (Automatic)

If the part you want to blur contains sensitive text — like names, emails, addresses, or numbers — BlurData can find and blur it automatically.

Steps

1. Drag and drop the image into BlurData
2. The app scans the image and identifies sensitive data: emails, names, addresses, monetary amounts, account numbers, license plates, IP addresses, URLs
3. Review the detections — select or deselect what you want blurred
4. Export the blurred image as PNG

Why This Approach Is Different

• Automatic detection: You don't need to hunt for sensitive information — the app finds it
• Offline processing: The image never leaves your Mac. No uploads, no third-party servers
• Batch support: If you have multiple images to process, you can do them all at once
• Custom regex: If your organization uses specific ID formats or codes, you can add custom patterns to detect them automatically
• Also handles PDFs: If you need to redact a PDF, BlurData uses native PDF redaction that permanently removes content from the file structure

BlurData costs $39/year with a 7-day free trial, so you can test it before committing.

Which Method to Use?

Here's a quick guide:

• Hiding a face or object in a casual photo: Preview's rectangle overlay is quick and sufficient
• Professional image editing with precise blur: Pixelmator Pro gives you full control
• Hiding sensitive text data (emails, names, numbers): BlurData's auto-detection saves time and reduces the risk of missing something
• Handling multiple images or documents regularly: BlurData's batch processing and custom regex make it practical for recurring workflows

Common Mistakes When Blurring Images

No matter which method you use, avoid these common pitfalls:

Mistake 1: Using a Blur That's Too Weak

A light blur might look hidden at a glance, but zooming in can reveal enough to reconstruct short text like phone numbers or codes. Always use a strong blur radius, especially for numbers and short strings. Read our comparison of blur vs. pixelate vs. black out for more details.

Mistake 2: Saving in the Wrong Format

If you use Preview and add shapes over sensitive data, make sure to export the file as a flattened image (PNG or JPG). Some formats can preserve annotation layers, which means someone could remove the shapes and see the original content.

Mistake 3: Forgetting About Other Areas

You blurred the main sensitive area but forgot about the email address visible in a notification banner, or a URL in the browser address bar, or a username in the menu bar. Always scan the entire image before sharing.

Mistake 4: Using an Online Tool for Sensitive Content

Uploading an image with sensitive information to a web-based blurring tool means that information passes through someone else's server. For anything truly sensitive, use a local tool that processes everything on your machine.

Mistake 5: Not Blurring Enough of the Surrounding Context

Sometimes the text next to a blurred area gives away what was hidden. For example, blurring a number after "Account Number:" doesn't help if the label makes it obvious what kind of data was there. Consider whether the surrounding context needs adjustment too.