Light
Interaction with Objects
An image sensor does not see an object but rather sees light as
reflected by the object. The incident light can be reflected, front-scattered,
absorbed, transmitted, and/or back-scattered.
Reflection – If the surface of an object is shiny, incident
light will reflect at an angle with the normal equal to the angle
of incidence. Some materials may cause a change in the polarization
of the light. In a shiny (specular) reflection, light from each
incoming ray reflects in a single direction. Specular reflections
are bright and unreliable; in many cases they saturate the image
sensor.
In diffuse reflection, generated by dull (diffuse) surfaces, light
from each incoming ray is scattered over a range of outgoing angles.
The intensity is reduced but very stable.
Scattering – If the surface of an object is rough, the
light may reflect, but over a wide angular range.
Absorption – The light can be absorbed by an object in
the form of heat, chemical reaction, etc. These processes are wavelength
dependent.
Transmission –
It is the light that passes through after undergoing
refraction at the entrance to an object. The light may
back-scatter when exiting.
Change of Spectral Distribution – This
change is wavelength dependent and causes a change in the remaining
light beam. Consequently, the image sensor may see an object in
a different color and sometimes differently shaped.
For more information, please contact
High-Tech Digital Technical Support.
310-265-8203
support@high-techdigital.com.
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