Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

3.17.5 C-scan display
C-scan display records echoes from the internal portions of test pieces as a
function of the position of each reflecting interface within an area. Flaws are
shown on a readout, superimposed on a plan view of the test piece, and both
flaw size (flaw area) and position within the plan view are recorded. Flaw
depth normally is not recorded, although it can be measured semi
quantitatively by restricting the range of depths within the test piece that is
covered in a given scan. With an increasing number of C-scan systems
designed with on-board computers, other options in image processing and
enhancement have become widely used in the presentation of flaw depth and
the characterization of flaws. An example of a computer-processed C-scan
image is shown in Fig. 11, in which a graphite-epoxy sample with impact
damage was examined using time-of-flight data. The depth of damage is
displayed with a color scale in the original photograph.