PDF to Image: Choose DPI for Screens, Print and Small Text
Understand how page size and DPI determine pixel dimensions, choose PNG/JPG/WEBP, and avoid oversized exports or unreadable text.
WrenPDF · · 5 min read
Exporting a PDF page as an image involves two separate choices: how many pixels to create and how to encode those pixels. DPI controls the first. PNG, JPG and WEBP control the second. Raising JPEG quality cannot restore detail that was never rendered at the chosen resolution.
Choose based on what the image must do. A small preview card, a full-screen slide and a printed page have different needs. Keeping a PDF as a PDF may be better when the recipient needs selectable text or crisp zoom at many sizes.
Connect page size to pixels
The useful calculation is width in inches multiplied by DPI. A page 8 inches wide rendered at 150 DPI produces about 1,200 pixels across. Doubling DPI doubles both width and height, so the pixel count becomes roughly four times larger.
That increase costs memory during rendering, even if the compressed output looks small on disk. Large posters at high DPI can hit a browser's drawing limits. WrenPDF may reduce resolution for unusually large pages rather than attempting an unmanageable canvas.
Pick a starting point
PDF to Image offers 72, 96, 150, 200 and 300 DPI, with 150 selected initially. Try 96 or 150 for screen sharing and inspect small text at its intended display size.
For printing, try 300 DPI if the printer and source content warrant it. A low-resolution scan inside the PDF does not gain genuine detail by being exported at a higher number. The result may simply contain more pixels describing the same blur.
If only one diagram matters, export the relevant page rather than the whole report. Several selected pages arrive as a ZIP; a single selected page downloads as an image.
Choose the image format
- PNG: useful for text, diagrams and transparency, with potentially larger files.
- JPG: useful for photographic pages when a white background and some compression loss are acceptable.
- WEBP: useful for modern web workflows; check the receiving application's support.
PNG and WEBP can use a transparent background. JPG cannot. Transparency also does not remove white pixels already painted into a scanned page image.
Check before distributing
Open the downloaded image and examine the smallest required text, thin lines and any barcode. Check its pixel dimensions, not just the DPI label. Then view or print it at the size the recipient will use.
If you only want a photo embedded in the PDF, use PDF Extractor instead. Rendering a full page and cropping a photo is a different workflow and can reduce useful detail.
For the rendering model, PDF.js explains page viewports and scaling. The practical consequence is straightforward: choose enough pixels for the intended use, then verify the actual output rather than assuming the highest setting is always best.
Open: PDF → Image, free, and your file never leaves your device.