Forensic Dentistry, Second Edition

218 Forensic dentistry

disadvantages. The two most common file formats are JPEG and RAW. The
simplest explanation of the differences between these two formats is that the
JPEG file format is a compressed image of the RAW image data the sensor cap-
tured when the photograph was taken, which yields a smaller file. The RAW
data file is quite large compared to the JPEG but still contains all the image
data and detail, allowing more versatility when working with the image.
RAW images require a separate proprietary “plug-in” program, usually sup-
plied by the camera manufacturer, to open them. These files are then saved in
a different non-RAW format when closing the altered file (Figure 11.17).
To understand the capabilities of any individual camera, the photogra-
pher should familiarize himself or herself with the operator’s manual and
perform several test runs of trial photographs in order to find the preferred
camera settings and lighting methods.
While most digital cameras are automatic point and shoot, there are still
some settings that must be applied before taking the photographs. One of
the most significant would be setting the ISO for the environment where the
photographs will be taken.
Other settings would include the file format that will be used to capture
and process the digital image (such as RAW or JPEG, which were discussed
previously) and the resolution of the resultant image, usually expressed in
megapixels. The more resolution, the more pixels utilized and the larger the
size of the file holding the digital data for the image.
When the digital camera settings have been applied, the photographer
is ready to take the photographs. Unlike photographic film, which has to
be processed before the images can be printed on paper, digital images can
be immediately viewed, evaluated, and if necessary, retaken. Once again, the
standard technique should be utilized.
Archiving digital image files must be addressed. Who among us hasn’t
had a computer crash, which involves the loss of all data on the affected
computer? The risk of the loss of the data or the integrity of the data of the
digital images requires the digital photographer to take additional steps to
protect the data. The most common task is making duplicate backups fre-
quently. This can involve writing the files to external removable hard drives,

Sensor

Readout

Electronics

ISO

Setting

Bayer

Interpolation

JPEG

Compression

JPEG

File

RAW

File

White Balance

Contrast

Saturation

Sharpness etc.

Figure 11.17 schematic of how a captured digital image is processed from the
time it is formed on the sensor until either a JpeG or raw data file is created.
(source: http://www.photo.net/learn/raw/.))