Overview
A smaller PDF is easier to email and more likely to meet an upload portal's limit, but compression is always a tradeoff. The correct target is the smallest file that still supports the reader's task, not simply the smallest number shown after export.
DocuKit offers two strategies. Preserve text keeps interactive page content while rewriting PDF structure. The image profiles render each page and place an optimized JPEG into a new PDF, which is effective for scans but changes searchable text and interactive features into pixels.
Key Takeaways
- Preserve text rewrites PDF structure without rasterizing pages, but it cannot guarantee that an already optimized file becomes smaller.
- Balanced, Smaller file, and Maximum rasterize complete pages at progressively lower DPI and JPEG quality.
- Scanned and image-heavy PDFs are the best candidates; archival masters and digitally signed files are poor candidates.
- File-size reduction varies with the source and can occasionally be smaller than expected—or not useful at all.
Step-by-Step Workflow
- Keep an untouched copy of the original PDF and note the receiving service's size limit.
- Upload the file and begin with Preserve text when search, copying, links, or vector detail matters.
- Run the compressor and compare the displayed original and compressed sizes.
- Open the result at 100% zoom and inspect the smallest text, thin lines, signatures, and diagrams.
- For scans, try Balanced first and move to Smaller file or Maximum only when the result remains too large.
What each compression profile does
Preserve text rewrites the PDF with object streams. Balanced renders at 144 DPI, Smaller file at 110 DPI, and Maximum at 82 DPI; the image profiles also lower JPEG quality as compression strength increases.
Those percentages are encoding inputs, not a promise of a particular file-size reduction. A PDF that already contains efficiently compressed images may shrink only a little. A large scan assembled from uncompressed photos may shrink much more.
When rasterizing is acceptable
Rasterized output is often acceptable for a read-only scan, a visual proof, or a portal submission that will only be viewed or printed. It is less suitable when someone needs to search, copy text, use screen-reader structure, complete form fields, follow links, or preserve vector artwork.
- Good candidates: receipts, photo scans, signed-paper scans, and visual reference copies.
- Review carefully: resumes, presentations, maps, and documents with small footnotes.
- Avoid for the only archival copy, accessible source documents, forms, engineering drawings, and signed originals.
A practical acceptance test
Check the output in the environment where it will be used. For an email attachment, open it on a phone and a desktop. For printing, print one page containing small text and a photograph. For a submission portal, stay below its limit with a little margin because systems may calculate size differently.
- Compare page count and orientation with the original.
- Zoom into the smallest type and high-contrast edges.
- Confirm that losing selectable text and links is acceptable.
- Keep the original file under a different name.
Frequently Asked Questions
Which compression level should I try first?
Start with Preserve text for searchable or vector documents. For scans, try Balanced first and use Smaller file or Maximum only if necessary. Always inspect the output.
Will text remain searchable after compression?
Yes with Preserve text. The three image profiles render each page as a JPEG, so their visual text remains but the original searchable text layer does not.
Why did my PDF not become much smaller?
The source may already use efficient image compression, contain few images, or be small enough that the new page images and PDF structure offer little savings.
Does compression preserve a digital signature?
No. The result is a newly created PDF and should not be treated as preserving the original file's cryptographic signature or archival status.