RTD info - European Commission - Europa

38 RTD info Special Science and Media September 2002
S C I E N T I F I C I M A G E
The technicalities
The Escherichia coli bacteria, photographed using two different techniques, assumes aspects
which at first seem to bear little similarity. The transmission electron microscope gives a
cross-section of its interior while the scanning electron microscope produces a 3D image.
The image assists words and
concepts. Even a graph, such as
in this edition of Istoria e
dimostrazioni intorno alle macchie
solari (Rome, 1613), enables
Galileo to explain what he
would subsequently call the
rings of Saturn. This drawing
was presented at Image and
Meaning, organised by the
Massachusetts Institute of Technology
in Cambridge, USA and
comprising an exhibition, conference
and debates. Felice
Frankel, a researcher and scientific
photographer, believes
that ‘good photographs grab
people’s attention and a good
image can help scientists and
the general public to understand
things more easily.’
#http://web.mit.edu/i-m/conference.htm
When photographs in the field of cellular biology (in vivo cells or coloured histological
cross-sections) are obtained by optical microscopy, the intensity, contrast and colour saturation
depend on a number of conditions (lighting, temperature, exposure time, UV light,
etc.) as well as the balance of the colour temperatures. In the case of fluorescence or specific
marking, the colours obtained are largely determined by the reactions produced or the use
of a particular wavelength. Images observed directly by digital files on a computer screen
correspond to given values which permit the representation of localisation. They could also
be processed in the form of density (grey-scale).
In the case of a transmission electron microscope (TEM) or scanning electron microscope
(SEM), the image obtained is always in black and white, with varying degrees of contrast.
The use of filters and the intensity setting will influence the colour temperature, and thus
its final rendering. The fact that some of them are presented in bichromy is an artefact.
Photographic emulsion is sensitive to wavelengths and contrasts and is able, depending on
the exposure times, to record phenomena that cannot be detected by other means, such as
in situ hybridisation or radioactive markings. Depending on whether or not filters are used,
the intensity setting will affect the colour temperature and thus its final rendering.
As Michel Depardieu explains, ‘digital imaging is more than just a change of technique or
support. It brings changes to research activities and information processing. The image can
be changed, or its content manipulated, in a way which not only changes the image but the
relationship to the image.’
‘In a problem, it is the most elegant
solution which is the right
one, the one which works. I
have often observed how the
beautiful works better than the
ugly…’ (Roger Penrose, British
mathematician who worked
with the astrophysicist Stephen
Hawking and ‘inventor’, in
1973, of a paving system with
no repeat pattern consisting of
six parts – which seem like four
– to amuse a hospitalised friend).