Dot code detection

The method according to any one of the preceding claims, wherein the reading the processed image to derive the dot code from the processed image comprises:

• determining, for a plurality of positions in the image, a match to a template representing a dot, selecting the positions for which a highest match has been determined,
• finding in the positions for which the highest match has been determined, pairs of positions at a distance that matches a dot to dot distance in the dot code,
• determining, for the pairs of positions a match to a template representing a dot code,
• selecting at least two pairs of positions for which a highest match has been determined,
• fitting, using the template, a dot code reading line onto the selected at least two pairs of positions, and
• reading dots of the dot code along the dot code reading line.

A dot code detection system for detecting a dot code comprising plural dots arranged on a background surface, wherein the dots comprise a centre surface which is at least partly surrounded by an edge surface, wherein a spectral reflectivity of the edge surface differs from a spectral reflectivity of the background surface:

• the dot code detection system comprising:
• a source of radiation configured to irradiate the dot code and the background surface,
• a reader configured to capture an image of the dot code and the background surface irradiated by the source of radiation;
• an image processing system configured to process the image of the dot code and the background surface irradiated by the source of radiation,
• wherein the image processing system is configured to:
• distinguish in the image the edge surface from the background surface based on the difference in spectral reflectivity of the edge surface and the spectral reflectivity of the background surface;
• process the image of the dot code by dilating in the image the edge surface of the dot, until the centre surface has been closed by the dilating,
• read the processed image to derive the dot code from the processed image.