Stamps have been collected for as long as they have been used. Apart from regular stamp collecting (whole series, themes, etc.) there is also an interest in cancellation marks. Some stamps are more valuable in stamped condition than in mint condition, especially if the stamps are clear and still readable. Extracting cancellation marks to make it available for further inspection is therefore interesting.
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Hemel, Armijn, "Extracting cancellation marks from stamps using image processing", Technical Disclosure Commons, (April 13, 2020)