Choose pages first, then the format
After opening the PDF, check the pages to export. PNG suits text, line art and screenshots; JPG suits photos but uses lossy compression. Output quality also depends on the resolution of images in the original PDF.
Which resolution?
72 dpi suits small on-screen previews, 144 dpi suits most sharing, and 216 dpi gives more pixels but uses more memory and storage. Enlarging cannot restore detail missing from the original document.
Check after creating
A download link is created for each page. Check that text is sharp and that orientation and edges are complete. If a page is too large, lower the resolution or use the desktop app. Exported images do not keep the PDF's copyable text layer or interactive forms.