Issue << content << Zebra and Rainbow Example of Image Quality Standard in TOFD and Phased Array Technique


2014. . No. 4(66) - Dec 2014, pp. 6-9

Zebra and Rainbow Example of Image Quality Standard in TOFD and Phased Array Technique

G. Nardoni, P. Nardoni, D. Nardoni, M. Feroldi

According to the Report at the 11th European Conference on Non-Destructive testing, Prague, 6-10 October 2014

Image quality is a fundamental parameter to evaluate the correct setup of the equipment referred to the calibration test. In TOFD technique the grey level, as contrast between positive and negative phase, is the main parameter for detection and sizing of defects. Three quality classes have been proposed to graduate the grey level. In addition tips resolution is also expressed as a quality parameter. The first class has zebra as an example of grey contrast. In Phased Array technique, image quality of the reference indication is characterized by a spectrum of colours. This image represents an echo dynamic curve of the reference reflector through which the size of findings is estimated. The first class has rainbow as an example of image standard. The paper presents with different examples the need to establish a standard quality of an image, in particular in the evaluation of the procedure demonstration. This will avoid the rejection of TOFD and Phased Array maps at the final stage of the constructions as it has happened also recently, causing delay and heavy economic consequences.
Keywords: non-destructive testing, ultrasonic flaw detection, defect sizing
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