STC Ltd. has implemented a service of digitization of NDT radiographic films in compliance with UNI EN 14096-2 class  DS – DB – DA
The service is based on the use of a special scanner for radiographs NDT applications, capable of providing high-end digitization.
All’ standard film formats can be digitized, up to a width of 35 cm (14 in.), Without limitation of length in any resolution between 50 microns and 500 microns. The digitizer is able to handle the full range of density (D = 0 up to 4.70 D) in a working range with contrast sensitivity required, so as to meet the requirements of class DS according to EN 14096 – 2 .

Digitization quality classes


All radiographic  film digitization systems are subdivided into 3 quality classes DS, DB and DA


DS –  the enhanced  technique  which performs  the digitization  with an insignificant  reduction of signal-to-noise  ratio and spatial resolution.

Application field: digital archiving of films (digital storage).


DB – the enhanced technique, which permits some reduction of image quality.

Application field: digital analysis of films, original radiographic  films have to be archived.


DA-  the basic technique, which permits some reduction of image quality and further reduced spatial resolution.

Application field: digitalis analysis of films, original radiographic  films have to be archived.


Each radiographic  film digitization system for NDT applications shall be identified with all working ranges of optical densities. it shall be classified by the quality class corresponding  to Table 1 and the maximum  MTF 20% value, corresponding to EN 14096-1, which can be performed by this system.

EXAMPLE        A digitization system of class DS 4,2 (scanner class DS (see Table 1), maximum MTF 20 % = 4,2 lp/mm (see Table 2)) can be applied for archiving of radiographs taken with X-rays above 200  KeV or y-rays and can be applied for all class DB and DA digitization tasks.


EN 14096 -2


Minimum requirements for film digitization quality classes


  • Density range and working ranges of the film digitization system


Table 1  defines  the  minimum  density  range  of the  radiographic  digitization  system.  In  this  density  range  the digitizer shall provide  a density contrast  sensitivity DCS with DCS < 0,02  Depending  on the construction  of the digitiser, this density range can be split into several working ranges.


The minimum digital resolution is given for devices converting the digital value proportional  to the optical density. lf

the digital value is converted proportional to the light intensity, the digital resolution has to be increased at least by 2 additional bits


Table 1 -Minimum density range of the radiographic digitization system with a minimum density contrast sensitivity


Parameter Class DS Class DB Class DA
Density rangea  DR 0,5 to 4,5 0,5 to 4,0 0,5 to 3,5
Digital resolution in bit >12 >10 >10
Density contrast sensitivity

DCS within DR

> 0,02 > 0,02 > 0,02
a      This density range may be splitted into separated working ranges.


  • Minimum spatial resolution of film digitization systems


Due  to  the  energy  dependence   of  the  inherent  unsharpness   of  industrial  X-ray  film  systems   the  following parameters (see Table 2) shall be observed:


Table 2 – Minimum spatial resolution of film digitization systems



Energy Class DS Class DB Class DA
keV Pixel size


MTF 20%


Pixel size


MTF 20%


Pixel size


MTF 20%


< 100 15 16,7 50 5 70 3,6
>100 to 200 30 8,3 70 3,6 85 3
>200 to 450

Se 75, Yb-169

60 4,2 85 3 100 2,5
Ir 192 100 2,5 125 2 150 1,7
Co 60, >1 MeV 200 1,25 250 1 250 1


NOTE 1    For the normal! check corresponding to EN 14096-1, the MTF 20 % value can be determined by the converging spatial resolution targets.


NOTE 2      Due  to possible  aliasing,  the converging spatial resolution targets can  give  less  accurate values  than MTF measurements.


NOTE 3      For energies lower than 70 keV the spatial resolution of the radiographic  film can be better than the scanner resolution required by the class DS 16,7. In this case the spatial resolution of  the scanner  should be adapted to the film resolution, or the original  radiographic film should be archived.






  • Digitization class depending on the radiographic testing class


The   standards ISO 5579,  EN 444,  EN 1435   or  EN

Radiographs taken according to these standards shall be digitized corresponding to Table  3.


Table 3 -Minimum digitization class depending on the radiographic testing classes A and B, if radiographs are taken on the basis of ISO 5579,EN 444, EN 1435 or EN 12681


wall thickness [mm]



Class DS


Class DB


Class DA

< 5 B A
> 5 B B A



NOTE           For the detection of cracks and fine imperfections Class DB or better should be used.


After digitization process all required image  quality  indicators shall be visible  in the digital image as on the original radiographic film.


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