Deskew PDF.

Manual mode starts at 0°. Make a small correction, then compare a long line of text with the grid. Fine nudges help you avoid changing a slight tilt into a larger one.

The angle is a correction to the displayed source. Check the preview rather than guessing whether the scan needs a positive or negative value.

Apply to all pages starts enabled. It is useful when one scanner setup produced the same tilt throughout. Turn it off when different pages lean by different amounts.

Navigate after making a change and confirm the scope label. A document with upright pages and tilted inserts should not receive the same correction everywhere.

Automatic deskew examines the page during processing. Use it when a document has obvious text lines and you would rather review a computed result than set each angle yourself.

Sparse pages, illustrations and unusual layouts can be ambiguous. Inspect the downloaded result, and return to manual correction when the automatic angle is unsuitable.

A higher output resolution can retain finer details when they exist in the source, but it cannot restore missing or blurred letters. Larger page images also take more space and memory.

Deskew creates image-based pages. Use Rotate PDF for a simple quarter-turn if you want to preserve native text and vectors without this raster conversion.