Never use pixelation to redact text

Not specifically Monzo or banking related, but because people often post screenshots and other things to this forum with personal information redacted… consider this a PSA :joy: The above is an interesting tech demo and great explanation. (Video is concise and comprehensible, and text has further details.)


So this isn’t safe then?


Best ROT13 it, to be on the safe side. Or ROT26, twice as secure!


What about drawing over it, like I do with iPhone screenshots?

If doing it on my PC, I edit it in MS Paint of all things, select the test and click DEL

I saw something about when people black out text, that if you change the brightness/saturation back and forth, you can view what’s under it.

I’ve tried it 3 or 4 times with pics from different people and I’ve never got it work.


I missed out the most important word here. I’ve never got it to work! :rofl:

Think that depends on what editing program you’re using, or not looking closely at the default settings. A 100% opaque black painted mark, or area fill, wouldn’t reveal anything. If it’s anything other than 100% opacity, or you’re using the highlighter tool… yeah, your trick will work.

If you’re having to ‘scrub’ backwards and forwards to black out text, there’s an opacity issue.

tl;dr, use a pen or shape tool - not a brush or highlighter tool - when blacking out text.


What’s my secret then?

As @HoldenCarver says, I think that’s only true if someone simply layers another vector graphic on top of the actual text. If you’re using a bitmap editor and exporting as a bitmap this shouldn’t work. There’s also a specific ‘redact’ feature in MacOS Preview (and I assume other PDF editors?) that I believe obliterates the underlying text instead of just covering it up with another object. This issue is actually mentioned towards the bottom of the article linked :point_up:

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19 February 2022 at 19:55

That killed my eyes. Brightness off now. Night shift back on.

Haha, I missed out “never” from my post!

I’ve tried it a few times and I’ve never got it to work!

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No, I don’t think that would even fit into the length of the redaction!