Most PDF problems are self-inflicted. I have seen the same seven mistakes repeatedly — from marketing teams sending 80 MB presentation decks, to people screenshotting PDFs to "convert" them. Every single one of these is easy to avoid once you know what to look for.
Mistake 1: Compressing a PDF multiple times
Every time you run a PDF through a compressor, you reduce the image quality a little more. Compress a PDF twice and the quality loss doubles. Compress it five times and images that looked acceptable start looking genuinely degraded.
What to do instead: Compress from the original file once, at the right preset. If you need a smaller result, go back to the original and use a more aggressive preset — not compress the already-compressed output again. Use Filero's Compress PDF tool and choose your preset carefully the first time.
Mistake 2: Taking a screenshot of a PDF to "convert" it
This one genuinely hurts to see. Screenshots are captured at screen resolution — typically 72–96 DPI. When you screenshot a PDF and turn that screenshot back into a PDF, you get a file that is larger than the original, with lower quality text and images, and with all the real text destroyed (it is now pixels, not characters). You also lose the ability to search, copy, or highlight anything.
What to do instead: If you need to convert a PDF to an image, use Filero's PDF to JPG tool — it extracts pages at proper resolution. If you need to convert to another document format, use the dedicated converter.
Mistake 3: Saving a Word document as PDF using "print to PDF" then re-saving as PDF
The system Print to PDF function varies significantly in quality across operating systems and apps. On Windows especially, Print to PDF from some applications compresses images more aggressively than the native Save As PDF option. The result is a lower-quality file than necessary.
What to do instead: In Word, always use File → Save As → PDF (or File → Export → Create PDF). This uses Word's own PDF engine with proper quality controls. Reserve Print to PDF for when there is no other option.
Mistake 4: Scanning documents using only your phone's camera app (not the scanner)
Taking a photo of a document with your regular camera app gives you a JPEG photo — not a scanned document. You lose auto-deskewing, auto-cropping, perspective correction, and proper document framing. The result is a large, tilted, shadow-filled image masquerading as a scanned document.
What to do instead: On iPhone, use Notes → camera icon → Scan Documents. On Android, use Google Drive → + → Scan. These use the camera sensor but apply document scanning algorithms on top of it.
Mistake 5: Sending a PDF without checking the file size
Many people export a presentation or create a scan and attach it to an email without checking the file size. The recipient gets a bounce-back, or worse, the email silently fails to deliver on mobile.
What to do instead: Right-click the file before attaching → Properties (Windows) or Get Info (Mac) to check the size. If it is over 10 MB, compress it first. Under 5 MB is safe for all recipients.
Mistake 6: Saving a PDF as JPEG to share it
Some people convert a multi-page PDF to a single JPEG to make it "easier to share." A JPEG can only hold one image — a multi-page document converted this way either loses all pages after the first, or gets flattened into one long image that is impossible to read normally. JPEG also uses lossy compression that degrades document text quality.
What to do instead: Share the PDF as-is. PDFs are universally supported on every platform. If the recipient specifically needs an image, use Filero's PDF to JPG tool to export each page as a properly extracted, high-quality image.
Mistake 7: Using an online tool that converts your PDF to images before merging
This is the sneaky one — it looks like it worked. Some online PDF mergers convert every page to a raster image, merge the images, then convert back to PDF. The result looks fine at first glance. But open it and try selecting text. If nothing highlights, your tool just silently destroyed the document structure: searchable text gone, file size increased, fonts degraded, internal PDF structure stripped out.
How to spot it: Try Ctrl+A to select all text in the merged PDF. If nothing selects, find a better tool. Filero's Merge PDF tool merges at the binary PDF level — text, fonts, and structure stay exactly as they were.
Frequently asked questions
How can I tell if a PDF has been damaged by one of these mistakes?
Three quick checks: 1) Try selecting text — if nothing highlights, pages were converted to images. 2) Zoom to 400% — if text looks pixelated rather than sharp at any zoom level, it has been rasterised. 3) Check file size relative to page count — a 50-page text-only document that is 15 MB has something wrong with it.
Can I recover a PDF that was damaged this way?
If text was rasterised into images — no. That data is gone and the document would need to be recreated from scratch. If the problem is over-compression, go back to your original source file and re-export at higher quality. Which is the real lesson here: always keep the original.
Which of these mistakes is the most common?
Compressing multiple times is probably the most widespread, because it happens gradually — someone compresses a file, sends it, the recipient compresses it again before forwarding, and so on. By the third or fourth pass, the images look noticeably worse. The fix is simple: always go back to the original and compress once.
Ready to try it?
Use Filero's free Compress PDF tool. No account needed, works on any device.
Open Compress PDF