Scanned documents frequently include a page or two that came out sideways or upside down, usually from how the paper was fed into the scanner or how a phone was held while photographing a page.
Sheet-fed scanners can flip orientation depending on which way a page was loaded, and phone scanning apps sometimes misjudge orientation on pages with little text near the top to anchor against.
If the scan also needs to be combined with other files or shrunk in size, rotating first means you're working with correctly oriented thumbnails when you move on to merging or compressing.
Ready to try it yourself?
Fix your scanned pages →Just the pages that need it — rotation is applied per page.
No, rotation doesn't recompress or otherwise alter the page's image data.