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Preview in macOS Big Sur is destroying PDFs

annoying.technology

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Re: Preview in macOS Big Sur is destroying PDFs

#121

Post by TwoBit »

izacus wrote: post #103
xxpor wrote: post #21

Why anyone treats PDF as anything but a write-once format is beyond me. It's so finicky that I'm not shocked bugs like this happen. The only programs I'd be reasonable sure wouldn't screw it up are Acrobat itself, and pdflatex and friends. I think we need a multi-image container format. It could be something that's literally a bunch of jpgs/pngs/pick your poison in a tar container, and given a new extension. OSes wou…

> Why anyone treats PDF as anything but a write-once format is beyond me. sigh These kind of ignorant statemens really annoy me. The massive part of PDF spec is dedicated to editable features (annotations, form filling and digital signatures) which are used by massive industries daily because it brings them a lot of value. It's REALLY not that hard to think for a second and remember why having a single file which can…

And yet PDF re-writing keeps getting screwed up. Probably because it really is a bad format for this, with the pages of docs notwithstanding.

Re: Preview in macOS Big Sur is destroying PDFs

#122

Post by markandrewj »

systemvoltage wrote: post #36
xxpor wrote: post #21

Why anyone treats PDF as anything but a write-once format is beyond me. It's so finicky that I'm not shocked bugs like this happen. The only programs I'd be reasonable sure wouldn't screw it up are Acrobat itself, and pdflatex and friends. I think we need a multi-image container format. It could be something that's literally a bunch of jpgs/pngs/pick your poison in a tar container, and given a new extension. OSes wou…

PDF is one of the best things IMO - it's like a docker container for documents. The way the original authors intended it to be, including fonts and all the things that go into making a document. For example, I personally like to purchase books that are in PDF format, not epub/mobi. I want to rely on professional typesetting from the publishers, not some front-end engineer's vision of what the ebook should look like a…

Generally the PDF copy of a book is designed to fit the format of the final printed book. The PDF is even often the deliverable sent to press.

If you are using something like an e-reader, or a smartphone, the PDF layout often doesn't translate well. Typesetting is also normally also done for ePub/Mobi, but the layout is tailored to the format of the device that the document will be read on. Although there are times when publishers just take the PDF and click 'convert to ePub', which isn't ideal.

There are also other advantages to different formats, when talking about things like programming books. As an example, working code snippets for web formats. I am thinking of things like Jupyter notebook when I say this.

As others have mentioned there are also a number of security risks associated with PDF.

I can't deny there are several books I have read in PDF format however.

Re: Preview in macOS Big Sur is destroying PDFs

#123

Post by matrixagent »

jabbany wrote: post #107
avalys wrote: post #23

This is a clickbait, sensationalist headline. “Saving a PDF with Preview in Big Sur can corrupt OCR text added by a third-party program” is more accurate.

Kind of agree the current title is a bit misleading. I've never used any editing features in Preview (I mean it's called "preview" so...) and reading the title I thought this meant it was mangling files even by opening them which would have been super scary. As for non-Acrobat software mangling PDFs after editing... Well that's much less surprising. I've even had Acrobat mangle stuff in PDFs after editing...

Well, technically you at least only have a chance of noticing the error after opening a PDF (again). I suppose that's because after saving the old, correct data is still in memory, but I don't know exactly when the corruption happens – would surprise me if it wasn't upon saving, though.

Re: Preview in macOS Big Sur is destroying PDFs

#124

Post by zepto »

jcrawfordor wrote: post #96
zepto wrote: post #65

Earlier quoted context omitted.

“The idea that this behavior in a PDF reader can be excused because the software that generated the PDF was not approved for the operating system the viewer is running on per the vendor.” Nobody is saying that. The suggestion is that the software that generates the PDF produces corrupt documents. The fact that the vendor of that software doesn’t approve it for Big Sur suggests that they might be aware that there are…

I worded it that way for two reasons, one of which is admittedly speculative: 1) It seems highly unlikely that ABBYY relies on some changed OS behavior in generating PDFs that leads to it producing PDFs that are malformed in such a way that is only revealed when they are rewritten by Preview. Behavior in Preview is by far a more likely cause of the problem. Generally the thing that changed is what broke... 2) To the…

I don’t really see why #1 is highly unlikely. PDF is very complex, and it’s easily possible that a generator could have a bug.

‘Generally the thing that changed is what broke’

This has been never been true in software engineering. Changed code reveals bugs which need to be fixed elsewhere all the time.

2. Yes, to the end user it looks like a problem with preview.

No, the fact that it opens at all doesn’t make it de facto “valid”.

Yes, handling questionable PDFs is part of writing PDFs handling software.

No, that doesn’t mean that all PDF handling software must or can feasibly handle any and all corruption.

The very fact that there are many kinds of questionably valid PDFs out there proves the point. Handling the the intersection of all the invalid PDFs is impossible.

Rendering correctly has nothing to do with this. PDFs have many attributes which are not rendered.

It really is on the document creator to produce a valid document in the first place.

It’s certainly on ABBYY to have tested this months ago and either fixed it, or publicized it.

Re: Preview in macOS Big Sur is destroying PDFs

#125

Post by unilynx »

bigbubba wrote: post #106
gfody wrote: post #87

Earlier quoted context omitted.

you can also embed images and fonts in svg, probably not as reliable as pdf for pixel-perfect reproductions everywhere though

Is there any way to embed raster graphics into an svg? If so, maybe svg could be used as a text-capable container for raster images.

Yep, they can, at least JPEG and PNG.

(and if you're not precise enough with your questions, some designers will simply send you a PNG-base64-blob-inside-SVG if you ask them "can we have a SVG version of that icon")

Re: Preview in macOS Big Sur is destroying PDFs

#126

Post by nine_k »

xxpor wrote: post #21

Why anyone treats PDF as anything but a write-once format is beyond me. It's so finicky that I'm not shocked bugs like this happen. The only programs I'd be reasonable sure wouldn't screw it up are Acrobat itself, and pdflatex and friends. I think we need a multi-image container format. It could be something that's literally a bunch of jpgs/pngs/pick your poison in a tar container, and given a new extension. OSes wou…

PDF is often called "electronic paper", meaning its primary use, typesetting documents on screen and paper alike.

I'd rather view that PDF is an electronic clay tablet. You can put any text or image on it, but once it's formed, you better not try to alter it, lest you break it.

Re: Preview in macOS Big Sur is destroying PDFs

#127

Post by duskwuff »

mhh__ wrote: post #11

Preview seems like a good example of something that's worth open sourcing. Not only will people end up doing work for you, you get eyes on the code and more direct issue tracking. Consumers get a product and they still have to go on Mac to use it.

For what it's worth, Preview is a relatively thin shell around Apple's own PDFKit:

https://developer.apple.com/documentation/pdfkit

Whether that could itself be open-sourced is an interesting question. (My concern would be that parts of it might be covered by Adobe NDAs.)

Re: Preview in macOS Big Sur is destroying PDFs

#128

Post by x86_64Ubuntu »

systemvoltage wrote: post #63
inetknght wrote: post #54

Earlier quoted context omitted.

> I want to rely on professional typesetting from the publishers, not some front-end engineer's vision of what the ebook should look like and how it should be presented to the user. I, on the other hand, do not whatsoever trust publishers. PDF runs software and that means that everything under the sun including malware and DRM can run on PDF -- and indeed that has occurred many times. It should be a non-starter for a…

There are many other formats, a myriad of text formats from asciidocs to markdown. For embedded devices and such, they work great I presume. Please don't mess with PDFs. 20+ year old technology that is shitty but works, I prefer keeping the status-quo.

If PDF had an "accident", and someone was able to do to it what Steve Jobs did to Flash, I would be very happy.

Re: Preview in macOS Big Sur is destroying PDFs

#129

Post by zepto »

mynameisvlad wrote: post #95
zepto wrote: post #70

Earlier quoted context omitted.

You’re a victim of ABBYY’s poor PDF generation, that’s what. Nothing excuses ABBYY if their PDFs are corrupt.

Wow, just wow. The PDF works fine before saving in Preview. As in, Preview itself will render the file perfectly fine with OCR. By all accounts, the PDF is completely valid and uncorrupted at this point. Making a change to the file and saving it in Preview is what causes the corruption. So how the hell could you possibly excuse Preview and call this a ABBYY issue when Preview is the one that causes the issue ? That's…

“By all accounts, the PDF is completely valid and uncorrupted at this point.”

Is it? I don’t see any accounts showing this to be a fact.

Re: Preview in macOS Big Sur is destroying PDFs

#130

Post by duskwuff »

ztravis wrote: post #85

My guess is that the output PDF is still valid, but that an embedded (subset) font has had its `ToUnicode` map stripped, so that there's no link between the character codes used in the text elements and the "actual" characters they represent (there are also other ways this corruption could happen, but dropping or mangling the `ToUnicode` map seems like a likely cause).

This is almost certainly it. I've seen similar issues with copy/paste from poorly constructed PDFs, often ones generated by "print to PDF" features.
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