Pages In, Pictures Out
Sometimes a PDF is the wrong container: a slide has to go into a document that will not embed one, a page needs to be posted where only images are allowed, or a design tool refuses anything that is not a bitmap. Screenshotting the page gives you whatever resolution your monitor happens to have, and a cloud converter wants the file before it will help.
This tool renders each page with the same engine your browser uses to display PDFs, at the resolution you choose, and hands back real images. Each page keeps its own dimensions and aspect ratio, so nothing is cropped, stretched or padded to a common size.
How to Convert a PDF to Images
Two settings decide almost everything about the output: how many pixels, and which format.
- Load the PDF you want to rasterise. Every page appears as a thumbnail and starts out selected.
- Pick the format. PNG is lossless and right for text; JPEG is much smaller and right for photographic scans.
- Pick the resolution: 72 DPI for the web, 150 DPI for general on-screen use, 300 DPI if the image will be printed or cropped into.
- For JPEG, adjust the quality slider if you need to. Ninety per cent is a good default and rarely shows visible artefacts.
- Deselect any pages you do not need, or type a range such as 2, 5-7 to pick them by number.
- Press Convert to images. Each page is rendered in turn, then download them one at a time from the grid or take the whole set as a single ZIP.
Understanding Resolution in a PDF
A PDF page has no pixels of its own. It is described in points, 72 to the inch, and only acquires a pixel size when something renders it. That is why the DPI setting matters so much here: it is not extracting an image that already exists, it is deciding how large to draw one.
The arithmetic is simple. Multiply the page size in inches by the DPI. An A4 page is 8.27 by 11.69 inches, so at 150 DPI it becomes roughly 1240 by 1754 pixels, and at 300 DPI roughly 2480 by 3508. Higher is not automatically better: a 300 DPI PNG of a dense text page can run to several megabytes, and on screen it will look no sharper than 150 unless you zoom in.
Output Size by Resolution
Approximate pixel dimensions and file sizes for a single A4 page, to help you choose before converting a long document.
| Resolution | A4 pixel size | Typical PNG | Typical JPEG | Best for |
|---|---|---|---|---|
| 72 DPI | 595 × 842 | 200–500 KB | 40–120 KB | Web, email, quick previews |
| 150 DPI | 1240 × 1754 | 0.7–2 MB | 120–400 KB | General on-screen use |
| 300 DPI | 2480 × 3508 | 2–8 MB | 400 KB–1.5 MB | Printing, cropping into detail |
Sizes vary a great deal with page content: a page of plain text compresses far better as PNG than a full-page photograph, and the reverse is true for JPEG. Treat these as orders of magnitude rather than promises.
Format Choice and Transparency
PNG is lossless, so text and line art come out exactly as rendered, with crisp edges at every stroke. That makes it the right choice whenever the image will be read rather than merely looked at, slides, diagrams, contracts, anything with small type. JPEG discards detail the eye is unlikely to notice, which suits photographs and scans of photographs and produces files several times smaller.
Every page is drawn onto a white background before rendering. PDF pages can have transparent regions, and JPEG has no alpha channel at all, so without that step a page with transparency would arrive with black patches where the paper should be. Filling white first also matches what you would see if the page were printed.
Rendering Locally, Including the Long Documents
Converting a PDF to images is the kind of task that online services handle by uploading, rendering on a server and emailing you a link. That is three copies of your document in places you do not control, for a job your own browser is perfectly capable of doing.
Here the rendering happens on your machine, using the PDF engine already built into the page. Nothing is transmitted, no link is generated, and the ZIP is assembled in memory rather than on a server. Pages are rendered one at a time with a pause between them so the browser stays responsive, which means a long document works without a queue or an email.