Define the intended use first
For an ordinary letter, readable text is the main requirement. A drawing may depend on fine lines and dimension labels, while a photograph needs different details and tonal distinctions. Establish whether the file will simply be read, processed with text recognition, enlarged or printed again later.
Check any requirements from the intended recipient. An upload limit is a technical constraint, not a reason to reduce readability without inspection. Where necessary, retain a better source file and a separate transfer copy rather than repeatedly compressing the only version.
Compare a representative page
Choose a page containing small text, a thin line or a faint stamp. A clean title page may be too easy a test. Scan the same original using two reasonably adjacent settings supported by the device, and open the results at the same viewing scale.
Compare the difficult area at an enlargement appropriate to the intended use. If the higher setting adds no useful detail, its larger file may be unnecessary. If characters already merge in the source image, text recognition will not reliably repair them. Also investigate alignment, the scanner glass and the original's condition.
Consider colour mode and compression
Black-and-white, greyscale and colour are separate choices. A coloured annotation can disappear or become harder to distinguish in a strictly black-and-white result. Conversely, a plain text letter may not need all the colour information in slightly tinted paper.
Compression further changes the saved result beyond the selected resolution. Look for blurred letters or marks around fine lines. Judge the final saved file rather than only the preview before export. Record resolution, colour mode and output settings together when preserving a working process for later use.
Recognise the limits of the original
More resolution cannot recreate details missing from the source. A blurred print or badly faded receipt remains a difficult original. Seek a better source copy when essential information is unreadable instead of treating a larger file with the same poor content as an improvement.
Different settings may suit different parts of a mixed collection. For example, separate ordinary text pages from small photographic inserts if the workflow permits. Record any changes so no page is overlooked with an unsuitable setting when the results are combined afterward. A deliberate comparison gives you a reason for the selected setting rather than a habit of always choosing the maximum.
