Photographic visual for Cover Versus Fill — Cover Versus Fill

Redaction

Cover versus fill

Everything else on this site tries to make a removal invisible. A redaction has to do the opposite: it has to be seen, because the person looking at the picture is owed the fact that something was taken out.

Two operations that look alike

A fill throws away the pixels under a region and builds new ones from the surroundings, so that the eye slides over the place where something used to be. Done well, nobody can tell anything happened. That is the whole point when the thing removed is a bin or a power line in a holiday photograph.

A cover throws the same pixels away and puts nothing plausible in their place: a black or white box, a colour that sits quietly on the page, or blocks too coarse to read. It is honest about the change. On a screenshot of a bank statement, a conversation or a form, that honesty is what separates hiding your own data from altering a record.

Why a fill is the wrong tool for a redaction

It misleads. A filled-in account number leaves a picture that looks complete, and a reader will treat it as complete.
It can invent. A fill over text sometimes produces shapes that look like other letters or digits, which is worse than nothing.
It blends. Every fill here has a soft edge so the seam disappears — and a soft edge lets the outer pixels of what was underneath show through.

That is why the photo redactor on this site uses a separate engine, called cover, with none of the softness the others have: no feather, no soft inner edge, full strength, and opaque even over transparent pixels. Its blocks of pixelation are never smaller than twelve pixels.

How to check a redaction

Look at it at 1:1. Zoom to actual size and pan across every cover. A single digit outside the box is the whole number for anyone patient.
Check the edge. A redaction should have a hard edge. A soft or feathered edge lets the outermost pixels of what was underneath blend through.
Check the format. Save a flat picture — PNG or JPG — not a layered file. A cover on a layer above the original hides nothing from anyone who opens the layers.
Check what else exists. The original, the cloud backup, the copy already sent. A cover changes one file; it recalls nothing.

Questions

Isn't a seamless fill more professional than a black box?

For a removal, yes. For a redaction it is the wrong goal. A fill tells the reader that the picture is complete, which it is not, and in a document someone relies on — a statement, a screenshot of a conversation, a photograph of a form — a silent change is the kind that misleads. A box tells the truth: something is here that you are not meant to see.

Is pixelation as safe as a solid box?

Not always. Fine pixelation of large text or a face can sometimes be guessed back, because the averaged blocks still carry the shapes' overall brightness. Blocks of at least twelve pixels make small text unreadable in practice, which is why the redactor here never goes smaller; for numbers, names and anything that matters, a solid cover is the safe choice.

What about blurring?

A blur is the weakest of the three: it spreads the pixels rather than discarding them, and a mild one can be partly reversed. The redactor here does not offer a blur for that reason.

How should an Aadhaar card be shared?

UIDAI offers a masked Aadhaar, which hides the first eight digits of the number, for exactly this purpose; use it for any official sharing. Covering a photograph of the card is a convenience for your own copy, not a substitute, and an identity document should never be altered.

Where to do it

Photo redactorOpaque covers and coarse pixelation, on this device.Remove text from a screenshotWhen text should genuinely disappear, from your own work.Photos you should not editIdentity, passport and exam photographs.Fill notesEvery guide on this site.