Tagged “scan-quality”
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What the sensor actually sees
The optical path sets sharpness before any setting does: a light source, a lens or none at all, and a white strip the scanner reads to calibrate itself.
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Duplex scanning, and what blank-page removal deletes
Two mechanisms hide behind one word, and the setting that tidies up after them is the only one on the device that can throw a page away.
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Diagnosing scan defects by their shape
A line down every page, a band across one, a shadow in a corner. Each defect shape points at a different part of the machine or the paper.
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Deskew, autocrop and auto-rotate: helpful until they aren't
Automatic image cleanup guesses where the page ends and which way is up. On an irregular slip both guesses can go wrong silently.
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Compression is why your scans look worse than the paper
The sensor read the slip correctly and the file lost some of it afterwards. Where lossy compression damages small print, and how to stop it.
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Scanning faded thermal paper
A faint slip is a contrast problem, not a resolution problem. The controls that help are exposure, colour mode, and lighting — in that order.
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Colour, greyscale, or bitonal for receipts
Bitonal makes the smallest files by throwing a hard threshold at every pixel. On faint thermal print that is exactly what you cannot afford.
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What dpi does to a receipt scan
Resolution buys detail up to the limit of the sensor and nothing after it. Where that limit sits, and why more dpi can make a slip harder to read.
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Scanning very long receipts
A till roll can be longer than any page a scanner expects. What long-paper modes actually do, where they stop, and how to capture the rest.