PHOTOGRAPHY 77
Scales: Underwater scales should ideally be matt yellow
and black. These are used for a variety of shots but
mainly for photographs of artefacts or a ship’s structure.
Place scales carefully so as to avoid masking any detail,
and try to keep them parallel to the frame of composi-
tion and the artefact.
Using film: Shoot and process a sample film to test equip-
ment and the local conditions before photographing
in earnest. Use the technique of ‘bracketing’ by taking
three shots, one correctly exposed, one over- and one
underexposed.
Documentation: Write up a photo-log as soon as pos-
sible after the dive.
Digital Darkroom
One of the most significant developments in modern
photography is the ‘digital darkroom’, where a computer
can be used to improve the original image. The image can
be digital or scanned from film. Ideally JPEG images
should be saved at the highest quality, with the least
compression. Once they are downloaded, a master copy
should be saved as a TIFF file because every time a JPEG
is changed and saved information is lost. The best prac-
tice is to work on the TIFF file then save a copy of the
final version as a JPEG for export. Never work on ori-
ginals in the digital darkroom – you never know when
you will need to go back to the beginning.
There are numerous software imaging packages on
the market and these are continually being developed.
Whichever package is chosen, it is essential to make sure
that the computer monitor is properly calibrated so that
it represents colours accurately and prints match what
is seen on screen. This is vital for colour management.
Make a note of print settings because the output will change
with the type of printer used, and also within a printer’s
quality options.
The image can initially be enhanced by adjusting den-
sity, contrast and colour, followed by a series of further
refinements including reframing or cropping, resizing
and making adjustments to isolated areas. A black-and-
white or greyscale version can be saved for publication,
but be sure to save the file at the highest resolution nec-
essary for the final output, and at the final output size,
especially for printing. The beauty of the digital darkroom
is that it is possible to experiment quickly, cheaply and
easily without being shut away for long hours in a dark
room brimming with toxic chemicals.
When scanning photographs, the negative or slide
should be scanned rather than a print, as film has the best
quality in terms of sharpness, tone and colour details.
However, slides must be scanned at a resolution that will
allow the image to be enlarged and still provide a good
enough quality at the final output size. Remember that
when the physical size of the scan is doubled, the resolu-
tion is halved. For the highest quality, shoot in RAW for-
mat and then process the images on a computer. This allows
adjustment of exposure, white balance, hue, saturation and
sharpness, with little or no degradation of the original
unprocessed data. Some digital SLR cameras come with
software to manipulate the unprocessed images. The
alternative is third-party software, which can be down-
loaded from the internet.
This section will give an overview of some of the
basic adjustments to improve an image, using Adobe
Photoshop as an example. Some of these can be found
under ‘Image/Adjust’. One of the clever things about
Photoshop is the use of ‘adjustment layers’. All of the
following can be done as an adjustment layer, which
sits above the original image file, the advantage being
that it is easy to experiment with changes without alter-
ing the original file.- Start off by adjusting the overall exposure –
brightness and contrast. This is best achieved by
adjusting ‘Levels’, which allows adjustment of the
highlights, mid-tones and shadows individually
on a histogram. Move sliders in from the left
(black) and the right (white) so that they are under
the ends of the histogram. Move the middle grey
slider left or right for the overall adjustment of
grey or mid-tones. Alternatively use ‘Curves’ which
permits very fine control of image density. - The overall colour is controlled by adjusting the
purity (hue) or vibrancy (saturation) of a colour with
the ‘Hue/Saturation’ controls. Start off by boosting
the saturation by +10 to +15 points. Hue can be used
to make an overall change if the image has a colour
cast (small adjustments); otherwise it is used to fix
and adjust specific colours. ‘Colour balance’ can also
be used to refine colour, particularly scenes with sev-
eral different light sources that can cause problems
in white balance. - Isolate areas of the image for local brightness and
contrast management and colour correction by
selecting an area of the image and making changes
inside it. There are three types of selection tools –
‘lasso’, ‘automated’, and ‘defined shape’ or ‘mar-
quee’. Once an area is selected, adjustments can be
made within that area. - Finally, sharpen the image, but only at the end and
at the final output size. Use ‘Unsharp mask’ found
under ‘Filter/Sharpen’, which looks for edges in an
image and makes them stronger. For images under
10 megabytes in size, try setting the ‘Amount’ to 120,