Blur an image with a brush instead of a box

Reach for freehand cover when the thing you need to hide is not a rectangle. A jawline is not a rectangle. Neither is a signature that tails off the line, or a logo printed on a shirt at an angle. A box is perfect for a line of text and clumsy for everything round. Cover a face with a square and you either leave an ear showing or you fog half the photo to be safe.

People search for a “brush.” Tools use that word loosely. This page owns the control shape: closed selection versus smear-as-you-drag. Face looks (pixelate versus blur) live on pixelate faces online. When the fill must be opaque for digits or names, use blur vs black bar. Background scenery that is not a person is on blur background.

Brush, or freehand selection?

A paint brush smears as you drag, so the result depends on how steady your hand was and how many times you went over the same spot. Thin streaks appear where the stroke sped up. Gaps appear where you thought you had already covered.

A freehand selection traces an outline, closes it into a shape, and then fills everything inside evenly with Blur, Pixelate, or Black bar. That second behaviour is what you usually want for privacy work. You get one clean region with consistent coverage instead of a patchy scribble. That is what Draw does in BlurThis: you outline, it fills. Closed selection versus brush is the whole distinction.

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How to cover with Draw instead of a box

1. Open the photo in BlurThis with Choose image. Keep Blur or Pixelate if the target is a face. Switch to Black bar first if the target is a signature, a handwritten note, a plate, or any short string of digits.
2. Switch the shape to Draw. You should see the cursor (or your finger) ready to trace, not a rectangle preview.
3. Zoom in until the target fills most of the frame. Tracing around a face at a fingernail’s size is guesswork.
4. Trace a loop around the thing you want hidden. You do not have to finish exactly where you started. The outline closes itself.
5. Lift your finger or release the mouse. The whole enclosed area fills at once. You should see an even cover, not a streaky scribble. If you wanted a Photoshop-style brush that paints while you drag, this is not that tool.
6. Not happy with it? Undo and trace again. Nothing is baked in until you tap Download PNG.

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Trace slightly wide

The most common mistake is hugging the outline exactly. Hair, glasses, and the edge of a jaw all carry recognisable information. A shape that stops at the skin leaves them. Go a little outside what you think you need. A cover that is two pixels too generous is easier to live with than an ear that is still sharp.

Same for text. If you are covering a handwritten signature, take the whole flourish, including the tail that runs off to the side. Initials in a corner, a date under the name, and a stamp next to it are part of the same secret. Cover them in the same pass or add a second shape.

Face blur or pixelation, even inside a tidy outline, does not guarantee the person cannot be identified from leftover appearance, a jersey, a doorway, or another frame. Look for the second identifier after the fill lands.

When to use a box instead

Straight UI elements. An email address in a header, a row in a table, a phone number in a contact card, a line that says demo@example.com. These are rectangles already, and a box drawn in one drag is faster and neater than an outline.

Mixing is normal. Box the address bar, draw around the face, bar the account number. Partial-region habits: blurring one part of an image.

Faces, signatures, and logos

Faces are the classic Draw job. Hats, hair, and a turned cheek stick out of a square. Trace around the head with padding, then look for a name on a jersey, a lanyard, or a mug. Those identifiers need their own cover. Soft blur or pixelate is for the person. A solid bar is for the label. Pixelate is not a security guarantee if a name tag still reads. Look comparison: pixelate vs blur on faces.

Signatures are not faces. They are short, high-contrast marks in a known alphabet. A light smear still shows the shape of the capital and the length of the tail. Switch to Black bar, then use Draw if the flourish is irregular, or Box if it sits on a printed line. The same rule applies to a stamp, a handwritten address on an envelope, and a doodle that is actually a name.

Logos on clothing, stickers on a laptop, and badges on a fridge are irregular too. A box over a tilted logo either clips it or eats the whole torso. Draw around the mark. If the logo is small type, treat it like text and fill solid.

A closed selection is only as strong as the fill

Tracing a tidy shape does not change what the filter does inside it. If what you covered is a short code, a card number, or a plate, switch the tool to Black bar before you draw. The shape works the same way, but it fills solid instead of smearing. Blur or pixelate is for “harder to recognise at a glance.” Solid fill is for “this must not be recoverable as text.” More on that split in blur versus bar, and on what recovery really looks like in unblur tools.

When Markup or gallery tools are enough

Phone Markup and gallery editors often offer filled shapes or a mosaic brush. Prefer a filled shape at full opacity for signatures and short strings. Treat a smear brush as a last resort: go heavy, go wide, and still check at 100% zoom. Highlighter is a tint, not a cover. Device walkthroughs belong on the iPhone and Android guides, not as a four-platform dump here. For a round face on a computer, paste into a browser tab and use Draw instead of approximating a circle with squares.

Troubleshooting

• The cover looks patchy. You used a smear brush or you treated Draw like one. Undo, zoom in, and draw one closed loop with padding.
• An ear or a glasses arm is still sharp. The outline hugged the skin. Trace wider. Hair and frames identify people.
• The signature still looks like a signature. Switch from Blur or Pixelate to Black bar and cover the whole flourish, including the date.
• Draw will not start. Confirm the shape is Draw, not Box. Box waits for a drag-rectangle. Draw waits for a path, then fills the interior.
• I saved the original by mistake. Download again and attach the PNG. Recents and the camera roll still hold the uncovered file. Closing the tab clears this page only, not your whole device.

Recap

Use Box for straight UI. Use Draw for faces, signatures, tilted logos, and anything that is not a rectangle. Draw traces a closed selection, then fills it. It does not paint as you drag. Zoom first, trace wide, fill evenly, then download a PNG. If the secret is digits or a name on a line, fill solid. Processing stays in the tab. That reduces upload exposure. It is not anonymity. Try Draw on a photo.