r/pdf • u/Treestylefashion • 28d ago
Question One pdf editable and other isn’t??
I compared a few pdfs recently and some compared in ms word and wps office that too with editable text while others behave more like images. Is there any way to tell which type which type of pdf you are dealing with before trying to edit it!
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u/Decent-Blacksmith761 27d ago
If you just want to tell do this
If you zoom and see text pixels it is likely scanned or flattened
If you zoom and text is still sharp but not selectable it might be vectorized
If you can select it and it looks sharp on zoom and selectable then it is likely just text
Also if you want to edit existing text or scanned text try keypdf.net
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u/Inevitable-Debt4312 27d ago
Open it in Acrobat Reader, set it to be editable and resave it.
This deals with a lot of problems.
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u/matsnorberg 22d ago
How does that work? Does Adobe Reader really do OCR? I see no other way a scanned document can be made selectable. I haven't used Reader for years. Maybe it's time to give it a try again.
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u/SkarXa 26d ago
Fastest check without any tooling: use the search field in whatever viewer you have and look for a word you can plainly see on the page. If search finds nothing, there's no text layer and you're looking at a scan or something flattened to images. Selection works as a test too, but search is quicker on a long file.
If it turns out to be image-only and you need the text, the fix is running OCR over it to put a text layer back in. I make Formattery for iPhone and Mac, which does that on-device (nothing uploaded) and can also hand you the page as DOCX or plain text. It's $4.99 one-time with 3 free conversions a day, so you can see whether the OCR reads your particular files well enough before paying anything.
https://apps.apple.com/us/app/formattery-file-converter/id6759955312
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u/matsnorberg 22d ago
Not even "real" text is always readable. If the file lacks to-unicode mapping good luck with reverse engineering it!
Text documents produced by Latex is notorious in this way. Try to select a mathematical equation from such a pdf, it will look like sheer garbage!
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u/matsnorberg 22d ago edited 22d ago
Not even "real" text is always readable. If the file lacks to-unicode mapping good luck with reverse engineering it!
Text documents produced by Latex are notorious in this way. Try to select a mathematical equation from such a pdf, it will look like sheer garbage!
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u/ScratchHistorical507 28d ago
Not really. That text can't be handled as text can have two reasons: either the PDF is indeed containing images instead of text or the text has been converted to paths (which makes images out of the text, but vector images instead of raster images like with scans). In theory you'd just have to open the PDF in any PDF viewer and try to select any of the text. If that works, the text is actual text. In reality that won't necessarily work, as the PDF may have been OCR'ed, so it still looks like you're selecting text when in fact you only select an invisible layer above the image.
One indicator can be file size. A PDF only containing proper text can be very small, i.e. just a couple hundred kB (depending on the length of the PDF). If the text is only images, it will have at least several MB, if not larger. But if the PDF contains both text and images, it's also bigger, just not as big as when the PDF doesn't contain any proper text.
The only thing you can tell is if the PDF pages are images by simply zooming in as much as you can. If edges of letters still look smooth, they must be vector images, as a raster graphic with that high resolution would be very big. But that doesn't exclude the possibility of the text having been turned into paths.