Converting between images and PDF: JPG/PNG to PDF and back
Images and PDFs solve different problems, so moving between them is one of the most common conversions there is. A few small choices decide whether the result looks right.
Two directions, two purposes
Turning images into a PDF and turning a PDF into images are opposite conversions that solve opposite problems. You make a PDF from images when you have a set of photos or scans — receipts, an ID, whiteboard shots, pages of a document — and want them to behave as one orderly file you can send, print or archive. You turn a PDF into images when you need a page as a standalone picture: to embed in a slide, post online, or share a preview with someone who cannot open PDFs.
Choosing between JPG and PNG
When converting a PDF to images, the format you pick has real consequences. JPG uses lossy compression that produces small files and looks excellent for photographs and scans, but can add faint halos around sharp text. PNG is lossless: it keeps everything perfectly crisp — ideal for slides, diagrams, screenshots and text-heavy pages — at the cost of much larger files.
The rule of thumb: JPG for pages that are mostly photographic, PNG for pages that are mostly text or graphics. If you are unsure and file size is not a concern, PNG is the safe, quality-first choice; if size matters more than perfect edges, JPG wins.
Resolution: sharpness versus size
When rendering PDF pages to images, resolution (measured in DPI) is the dial between sharpness and file size. Screen resolution is fine for web and email previews. Print resolution suits most everyday needs and is a sensible default. High resolution is for zooming in, printing or re-editing, and produces proportionally larger files. Pick the lowest setting that still looks good for what you are doing — going higher than you need just inflates the files.
Page size when building a PDF
Going the other way, from images to a PDF, the page-size option shapes the result. "Fit to image" makes each page exactly the size of its image with no margins, which is what you want for screenshots, receipts and scans where a white border would look wrong. "A4" centres each image on a standard page with margins, which is right for documents you intend to print. Add your images in reading order, since the pages follow the order you provide.
Keeping the round-trip private
It is easy to forget how sensitive image-to-PDF work often is: the photos people bundle into PDFs are frequently IDs, receipts, signed forms and personal documents. Pdfect runs every one of these conversions in your browser — images embedded into a PDF, or PDF pages rendered to images — so none of it is uploaded. The whole round-trip, in either direction, happens on your device, which is exactly what you want when the images are of your passport rather than your holiday.
A quick decision guide
Most of the choices in this conversion come down to a handful of simple rules. When you are unsure, these defaults will not steer you wrong:
- Photos or scans you want as one file — images to PDF, added in reading order.
- Screenshots or receipts — images to PDF with "Fit to image" so there is no white border.
- Documents you will print — images to PDF with "A4" page size and margins.
- A PDF page you need as a picture — PDF to images, choosing JPG for photographic pages.
- Slides, diagrams or text-heavy pages you want kept crisp — PDF to images as PNG.
- Not sure about resolution — start at print quality and only go higher if you will zoom in or print large.