Datasheet

4
c h a p t e r 1: DIGITAL IMAGING BASICS, WORKFLOW, AND CALIBRATION ■
The dynamic range of a captured scene is an important yardstick for quality
(Figure 1.2). This is the brightness range from dark to light that affects how much
detail can be rendered in the darkest and lightest portions of the scene. Dynamic range
is often represented in f-stops. Digital cameras can often capture a range of 11 f-stops
from black to white, whereas a paper print from a desktop inkjet printer might have,
at best, a range of five f-stops. Regular offset lithography, such as magazine print-
ing, has even less dynamic range—typically four f-stops or even less. This disparity
between capture and output is at the heart of reproduction problems because we
often have to determine how we are going to compress the range of an image to fit the
output. You will often hear about “bit depth” in the same breath as dynamic range.
Bit depth refers to the number of steps between black and white that are encoded in
a digital capture. Higher bit depth captures have a finer density of steps and yield a
smoother ramp from black to white; however, bit depth does not determine dynamic
range. It is certainly better to have higher bit depth with wider dynamic range, but
the two are not necessarily interdependent.
More steps
Lower dynamic range Higher dynamic range Higher bit depth
Lighter
Darker
Figure 1.2 Dynamic range and bit depth
The RAW signal from the camera chip can be processed either in the camera
firmware or later in software under user control. There is some debate over the merits
of both approaches. Generally, if you opt to have the camera do the processing, you
will be shooting JPEG files to the memory card or directly to a computer.
Note: JPEG stands for Joint Photographic Experts Group, the organization that developed the file
format.
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