film type, and chemical film processing, among others [3]. Human visual inspection of weld
defects is an extremely difficult task, as reported in the first paper on the subject in 1936 [1].
Conventional interpretation of radiographic films performed by qualified inspectors certified
for that task is highly subjective and is subject to errors, in addition to being a slow and
expensive process [4,5]. To minimize this problem numerous investigations on automatic
weld inspection appeared making use of the development of computers and digital image
processing and pattern recognition techniques, and from image digitization devices such as
CCD cameras [6,7], much work was done trying to develop techniques that could optimize
the radiographic aspect in terms of precision, time and cost.