Placing Page Images in Slides and Documents
Exporting a page as an image is the easy part. The common disappointment comes next, when the image is dropped into a slide or a report and turns out soft, heavy, or both. The cause is almost always a mismatch between the resolution produced and the size the image is finally displayed at.
The destination decides the resolution
An image has no inherent sharpness. What matters is pixel density at the size it will be seen: the pixel count divided by the physical or on-screen dimensions it ends up occupying. The same 2000-pixel-wide image is generous across a quarter of a slide and inadequate across a full printed page.
So the useful question is not "what resolution should I export at" but "how big will this be when someone looks at it". Work backwards from that. A figure that will occupy half the width of a slide needs roughly half the pixels of one that fills it.
Exporting far beyond what the destination can show is not harmless. The extra pixels are discarded at display time, but they are carried in the file, slow down editing, and bloat whatever you send. Overshooting is a real cost, just a less visible one than blur.
Slides
Presentation software works in a fixed canvas. A 16:9 deck is 1920 by 1080 points in most tools, which means an image spanning the full slide width needs about 1920 pixels to be pixel-exact on a standard projector, and roughly double that to stay crisp on a high-density laptop screen.
For a typical A4 page placed across most of a slide, scale 2x or 3x is the sensible range. That produces something between 1200 and 1800 pixels wide, which covers projection comfortably. Going to 6x or higher adds megabytes per slide and nothing a projector can resolve.
The exception is a page you intend to zoom into during the talk, or a dense table the audience is meant to read. There the effective display size is much larger than the slide, and a higher scale is justified.
Word processors and printed reports
Documents that will be printed are the demanding case, because paper resolves far more detail than a screen. The long-standing convention is 300 DPI for general printing and 350 DPI for commercial work, measured at the final printed size of the image rather than the size of the original page.
This is where people get caught out. A full A4 page reproduced at full size on paper needs roughly 2480 by 3508 pixels at 300 DPI, which is scale 4x or above. But the same page shrunk to a quarter-page figure only needs a quarter of the linear dimensions, so scale 1x or 2x is plenty.
Word processors complicate this by silently recompressing images on save or export. Many default to around 220 DPI for anything placed in a document, which will undo a careful high-resolution export without warning. If print quality matters, find that setting and turn it off before exporting to PDF.
Blur, halos and the second compression
A page image that looked clean on its own but is fuzzy in a document has usually been through two lossy steps. The first is the export to JPG, the second is the recompression applied when the document itself is saved or converted. Each pass throws away information, and the second pass works on the artefacts of the first.
Text suffers most. JPEG compression was designed for photographs, where gradual tonal change is the norm, and it handles the hard black-to-white edge of a letterform badly. The result is a faint grey mist around characters, most obvious on headings and in tables with thin rules.
The fix is to avoid lossy compression for text-heavy pages. PNG stores the rendered pixels exactly and will never introduce halos, at the cost of a larger file. WEBP sits in between and is usually cleaner than JPG at a comparable size. If the page is mostly photographs, JPG at quality 0.8 to 0.9 is fine.
A practical procedure
Start by measuring, roughly, how wide the image will be where it lands: a fraction of a slide, a column width, a full page. Multiply that width by the target density — around 150 pixels per inch for screen-only work, 300 for print — to get the pixel width you need.
Divide that by the page width in inches to get the DPI, then divide by 72 to get the scale. An A4 page is 8.3 inches wide, so a full-page print figure at 300 DPI needs about 2490 pixels, which is 300 DPI, which is scale 4.2 — round up to 5x. The same page as a half-width screen figure lands near 1x.
Then check one page before converting the whole document. Export a single page at your chosen setting, place it where it will actually live, and look at it at the size the reader will. This takes a minute and saves rerunning a fifty-page conversion.
Why PDFs get large, and what helps