Convert PDF to PNG

If you need a picture of a PDF page, this is usually the conversion you want rather than the JPG one, and the reason is worth thirty seconds. A document page is made of hard black shapes on flat white — letters, rules, table borders. JPG compression was designed for photographs, where colour shifts gradually, and it deals with hard edges by blurring them slightly and adding a faint halo. On a photograph you never notice. On a page of ten-point text you notice immediately: the words look slightly furred, as though the page had been photocopied one time too many.

PNG has no such problem. It stores every pixel exactly as drawn, so the letters are as crisp in the image as they were in the document. For a page going into a slide, a report, a bug ticket or anywhere somebody has to read it, that difference is the whole thing.

The size question usually resolves in PNG's favour too, which surprises people who have learned that PNG means large files. That rule comes from photographs, where PNG is genuinely inefficient. A document page is mostly identical white pixels, and identical pixels are exactly what PNG compresses best. A text page as a PNG is often smaller than the same page as a good-quality JPG, and always sharper.

Sharpness is something you control here, and it works unlike any other conversion on this site. A PDF holds no pixels at all — it describes where every glyph and line goes, which is why you can zoom into one forever without it going blocky. Converting to an image means picking a size to draw at.

The default of 150 dpi is comfortable for reading on screen; raise the Resolution setting if the picture is going into print or somebody needs to zoom in. You are not enlarging anything, so nothing gets softer. The setting runs from 36 to 600 dpi, and 600 draws an A4 page about 4960 pixels across.

A scan is a photograph of paper wrapped in a PDF, and it does have a fixed resolution — the one the scanner used. Drawing it larger stretches the photograph without adding detail, and for a scan of a page, JPG may even be the better target since the content is photographic rather than crisp to begin with.

A PNG holds one image, so a document of forty pages is forty files — that part has no honest way around it, and what changed is that you no longer have to ask for them one at a time. Leave the Pages box empty for the whole document, or name a selection: 1-3, 7, 10- all work, and asking for page 12 of a nine-page file comes back saying so rather than handing you the cover.

And the words become pixels: the result cannot be searched, selected or copied. If somebody needs the text rather than the look of the page, open the PDF in a reader and copy it straight out, because it is still text right up until this conversion draws it.

Charts, plans and technical drawings are the case where PNG earns its size. They are made of flat fills and thin lines, which is exactly the structure JPG smears — a hairline on a drawing is one or two pixels wide, and JPG cannot represent it without ringing around it.

For a diagram, render at a higher resolution than you think you need and scale the image down afterwards if it is too big. Detail that was never rendered cannot be recovered, and 300 dpi on a page of fine lines is not extravagant.

A PDF page has no pixels. It is described in points — a72nd of an inch — so a rendered image only has a size once you choose a resolution, and the same page can legitimately come out at 595 pixels wide or at 2480.

The default of 150 dots per inch gives roughly 1240 pixels across an A4 page, which is comfortable on screen and too coarse for print. Choose 300 if the result is going to be printed or if the page is dense with small type, and expect the file to be four times the size — the pixel count goes up with the square.