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How to blur or redact part of a screenshot

A step-by-step guide to hiding sensitive information in screenshots — and why most blur tools don't actually protect you.

Updated September 2026

Why blurring a screenshot is harder than it looks

Most screenshot tools "blur" by shrinking the image and scaling it back up. The pixelated result looks unreadable to a human, but the underlying data is still in the file. AI depixelation services can statistically reconstruct faces, text, and numbers from these patterns — a blurred credit card number is not as safe as it looks.

Real redaction has to destroy the source pixel data, not just disguise it. That's exactly what ScreenMark's blur tool does.

How to blur part of a screenshot in ScreenMark

  1. 1Paste your screenshot. Open the ScreenMark editor and press Ctrl + V — or drag & drop an image file.
  2. 2Pick the blur tool. Select Blur / Redact from the toolbar (shortcut B).
  3. 3Choose your mode. Pixelate gives the classic mosaic look; Redact fills the region with a solid colour.
  4. 4Drag over the sensitive area. Adjust or move the region afterwards if you need to — full undo/redo is supported.
  5. 5Hit Export & Copy. The annotated image lands on your clipboard, ready to paste into Slack, Jira, or email.

Pixelate vs. redact — which should you use?

Pixelate keeps visual context (readers can see something was there, roughly its shape). Redact is the safer-looking choice for high-sensitivity data like credentials — the region is a solid fill. Blur is not a guarantee that covered pixels are unrecoverable.

What blur and redact do

Each mosaic block is sampled from the original pixels, then deterministic noise is injected into the red, green, and blue channels independently. That is harder to reverse than a simple downscale. It is not a guarantee that covered pixels are unrecoverable.

Annotation runs in your browser. Export & Copy also writes a history item (see privacy notes) that you can reopen or delete for a limited time.

Try it yourself — free

Open the editor and follow along. Takes seconds to get started.

Open the Editor