Operating Manual

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In addition algorithms have been developed for e.g. the comparison of parts of an image with
conformance criteria, carrying out dimensional checks (sizing), for instance to measure
remaining wall thickness (see figure 37-16).
For this latter function algorithms exist that takes the source-to-object distance and the nomi-
nal pipe diameter as a reference to calculate remaining wall thickness or metal loss due to cor-
rosion. Also defect area measurement, image statistics and a reporting module are part of the
tools of the work station.
In cases of stationary DR systems in use for large production quantities so-called
"Assisted or Automated Defect Recognition” (ADR) programs (software algorithms) can be
applied with no human interference to speed up uniform interpretation of images.
Apart from the original image and its imprinted exposure parameters, on a true copy
comments and display characteristics (e.g., zoom, contrast, filters) can be superimposed and
archived as well. This enables inspection professionals to streamline the process and improve
the quality of distributed inspection information.
Figure 38-16 shows a screen
shot made of the worksttions
display. The screen shows
the results of an on-stream
exposure on a CR plate
taken of a valve with con-
necting pipe.
The screen shot includes
one of the selectable frames
of the report module.
The image itself shows marks
(white lines) super-imposed
by the workstation’s operator
to establish the remaining
wall thickness at those places
to be calculated by the soft-
ware.
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Versatility of the software
Images can be adjusted and enhanced in
many ways: brightness, contrast, sharpness,
noise suppression (averaging), rotation, filte-
ring, inversion, colouring, magnification,
zoom-pan-scroll, etc.
In this way, hidden details can be made visi-
ble, see figure 34-16.
Figure 35-16 graphically shows the effect of
two control mechanisms for selecting a part
of the density range of the image for a closer
look. The Z-shape can be shifted from left to
right through the whole range of densities of
the image. The angle of the vertical part can
be changed to increase the width of the
window (steeper or more flat) to alter the
range of contrast/densities.
The position of the “working point” determ-
ines the brightness of the image. In this
graph 16 grey levels on the digital image
result in one level on the monitor, this can be
set at 1-to-1. These are a few examples of the
versatility of the adjustment features provi-
ded by the work station.
Figure 36-16 shows the effect on an image by contrast enhancement and sharpening. Here
the contrast improvement, flat Z-shape (wide density window), makes the interior of a valve
clearly visible compared to the initial image. It proves that the information is present in the ini-
tial image but has to be adjusted to make it visible for the human eye.
Fig 34-16. Effect of image- averaging on noise
Fig. 36-16. Image enhancement in two steps
Original image Contrast improvement Sharpness improvement
Fig. 35-16. Flexibility of image (grey values) adjustment
Density window (contrast range)
Adjustable
angle
Black
256
Black
White
Digitized image
Grey levels
High resolution monitor / grey values
700 grey values
Selectable
brightness level
(working point)
Fig. 37-16. Wall thickness profile from on-stream image of figure 28-16 and report with statistics of all WT measurements
OD ID
WT
Fig. 38-16. On-stream image and report of a valve
WT 1
3.5  0,1 mm
WT 2
1.3  0,2 mm