This research focused on 4-wheel CLP image according
to the regulation of Thailand’s Land Transportation
Department. An example of 4-wheel Thai CLP image is
shown in figure 1. A CLP image is composed of two lines.
The upper line consists of 2-position character category,
following by 4-digit running number. The lower line
represents province name. Figure 2. shows the system
structure of CLP recognition. After inputting image,
preprocessing performed for transforming the image into
binarization (black-and-white) formatted and for reducing
noise. Next, line segmentation, and character segmentation
of the upper line would be conducted. Then 25 feature
values representing black-color intensity of 25 blocks
for each segment would be extracted. In recognition phase,
Hausdorff Distance technique was used for similarity
measurement.