Many researches have been done on car license plate
(CLP) recognition. However, these are no sufficient
number of works on Thai CLP. The existing works on Thai
CLP have been focused on localization, extraction, and
partial recognition (only for upper line) of the license plate.
Generally, Thai CLP has 2 lines (upper and lower). The
upper line presents character category in 2-position
formatted, following by running number (up to 4 digits).
The lower line presents province name. Recognition of the
lower line is a difficult task because Thai words can be
composed of 4 levels (top level, above level, base line and
below level). Hence, appearance of noises in the original
image easily causes misrecognition. This paper presents
an approach to recognize off-line entire Thai CLP using
Hausdorff Distance technique (HD) for similarity
measurement. The recognition rate obtained by the
proposed method is 92%.