lows
ate.
ns C4
5
| COS«
, 7000
,0019
,0312
,5683
,0014
,0198
on-
| we get
Once the parameters of light fall - off are known, compensation of
this particular effect can generally be executed analytically. This
affords, however, images in digital form. The formulas have to be
applied in the negative sense defining the image center as the oriain
of o with D = 0, neglecting the linear part.
5. Digital Reproduction of the Light Fall - Off Phenomenon
General advantage of a rigorous analytical approach is the possibility
to analyse the behavior of a phenomenon theoretically. For the problem
discussed here this means, that we can reproduce the measured conditions
digitally. Moreover the particular effect caused by an additional
linear disturbing function can be demonstrated. Two examples are dis-
played in Fig. 7.
The study of light fall - off in camera lenses is a limited, but
necessary step with regard to describe the image grey values as à func-
tion of the object characteristics properly. The LAMBERT reflector used
for full frame calibration here, can be applied beyond that in order to
determine the reflectance factor of particular objects and thus provide
another contribution to the entire complex.
b
ight fall-off components for the evaluated
a
Fig. 7: Simulation of 1
configuration (f - 5.6)
a) Radial component ( C4 - 0.6229 ; c2 7» 0 )
= 0 3 Co = 0.00194 )
b) Linear component ( C1
The steps correspond to the following densities [p] :
, MM |
hd t dl |