Graphics Programs Reference
In-Depth Information
—
The size of a digital image is
measured in pixels. Images with
large pixel dimensions are ca-
pable of producing big prints
and are generally better qual-
ity.
The current standard is known as 24-bit color or 8 bits per Red, Green and Blue channel. A
picture with this depth is made up of a selection of a possible 16.7 million colors. In practice
this is the minimum number of colors needed for an image to appear photographic. In the
early years of digital imaging, 256 colors (8 bits of color per channel) were considered the
standard.
Color or bit depth deter-
mines the number of colors
possible in a digital file.
Confusingly the number of
colors is often referred to
as 'bits per color channel'
with most files being made
up of three channels - Red,
Green and Blue. This gives
a total of three times the
bits per channel.
Images below:
1. 8 bits per color channel
or 24-bit total color
(16.7 million colors).
2. 8-bit total color
(256 colors).
3. 4-bit total color
(16 colors).
4. 1-bit total color
(two colors).
Although good for the time, the color quality of this type of image is generally unacceptable
nowadays. In fact, new camera and scanner models are now capable of 12 bits per channel
(36-bit color altogether) or even 16 bits per channel (48-bit color altogether). This larger bit
depth helps to ensure greater color and tonal accuracy.
The steps in the digital process
The digital imaging process contains three separate steps - capture , manipulate and
output .
Capturing the image is the first step. It is at this point that the color, quality and detail of
your image will be determined. Careful adjustment of either the camera or scanner settings
will help ensure that your images contain as much of the original's information as possible.
In particular, you should ensure that delicate highlight and shadow details are evident in
the final image.
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