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PostPosted: Sun Sep 04, 2016 6:53 am 
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Trying to blur some sensitive portions of a document. Doesn't seem to be an easy secure way to accomplish this.

Ideas?


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PostPosted: Sun Sep 04, 2016 7:33 am 
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How many pages is it?

i think for safety it'd be better to save it as a graphic format & blur or block it in a graphic app, like graphic converter.

I have PageStream, where you can load a PDF & obscure anything easily though.


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PostPosted: Sun Sep 04, 2016 7:54 am 
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Provided you don't want to retain the text of PDF as text, you can import it into a graphics program at a fixed size, thereby turning it into a bitmap. You can then draw on it, including putting black/white boxes over text. Many effects can be undone to regain access to the text (for a time criminals used the swirl effect to obscure their faces, but you can swirl in the opposite direction to regain a good enough image of their face), but a black or white box is just a box.

The biggest problem with editing it while retaining the text and drawing on top is that the underlying text typically remains intact and can be extracted from the document. Earlier this year or maybe last year there was a redacted document released that became political fodder once a way to extract the complete text was discovered. All the redacting was simply a graphics layer floating over the text, remove the layer, the text remains.

Anyway, once you're done editing, simply print and save as PDF to get the file back into PDF format.

You will want to import it from PDF at a fairly high DPI (e.g. 600) if the objective is to print the document at some point later.


Last edited by MonkeyBoy on Sun Sep 04, 2016 2:42 pm, edited 1 time in total.

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PostPosted: Sun Sep 04, 2016 12:59 pm 
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I remember PageStream from my Atari days. I don't have the Mac version though. Seems like this would be built into preview but I guess not.


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PostPosted: Mon Sep 05, 2016 6:10 am 
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MonkeyBoy wrote:
Provided you don't want to retain the text of PDF as text, you can import it into a graphics program at a fixed size, thereby turning it into a bitmap. You can then draw on it, including putting black/white boxes over text. Many effects can be undone to regain access to the text (for a time criminals used the swirl effect to obscure their faces, but you can swirl in the opposite direction to regain a good enough image of their face), but a black or white box is just a box.

The biggest problem with editing it while retaining the text and drawing on top is that the underlying text typically remains intact and can be extracted from the document. Earlier this year or maybe last year there was a redacted document released that became political fodder once a way to extract the complete text was discovered. All the redacting was simply a graphics layer floating over the text, remove the layer, the text remains.

Anyway, once you're done editing, simply print and save as PDF to get the file back into PDF format.

You will want to import it from PDF at a fairly high DPI (e.g. 600) if the objective is to print the document at some point later.

Thanks MB. I'll give this a try.


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PostPosted: Mon Sep 05, 2016 7:53 am 
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If this is something habitual and you don't mind paying, there is PDFStudioPro.

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PostPosted: Tue Sep 06, 2016 8:24 am 
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Used Graphic Converter to open pdf file (600dpi) and easily remove the text I wanted to remove just prior to printing the document. It worked just fine. I guess I could have saved to a different format (as suggested here in other posts) and that would have allowed for electronic delivery but I'll save that for another time when I have more confidence in the end result being secure.

Thanks for the help all!


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PostPosted: Tue Sep 06, 2016 10:37 am 
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The thing about opening it in a photo editing program and then printing it to PDF is that the end result is basically a large graphic, none of the original text remains as text. If you opened an illustration and printed it to PDF it would similarly be a large graphic stored in a PDF document.

It could be OCR'd back into text but the parts you remove are still removed, it can't OCR a box.


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PostPosted: Mon Sep 12, 2016 11:57 am 
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To get by, converting to bitmap and eliminating the text will get the job done. However, as MB has pointed out, you text is now a graphic which is ok at 600dpi if it's basically B/W. If there are colours and graphics in the document it might weigh a bit more in size. Of course it will not be searchable etc but if it's a one-off or occasional, it's an easy solution.

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BLAKE: [to Avon] Is something wrong?
AVON: It just occurred to me, that as the description of a highly sophisticated technological achievement, 'Avon's gadget works' seems to lack a certain style.


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