Why PNG for PDF pages
PNG is lossless, so text, tables, charts and line drawings stay perfectly sharp. That makes it the right choice for slides, documentation screenshots and anything you'll edit further.
For pages that are mostly photographs, PDF to JPG gives much smaller files with little visible difference.
Pages are drawn on a white background, like paper.
How it works
Vimorby reads the PDF with pdf.js and draws each page at the DPI you choose: 72 for previews, 150 for screens, 300 for print. Pages are processed one at a time and released as soon as they are saved. Several pages download together as a ZIP.
Your files are processed by your own browser, inside this tab. Nothing is uploaded, so there is no server copy to delete, and the page keeps working if you go offline after it loads.