Bits

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• Bits Bytes
• (are not junk food!)

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Bit is short for binary digit, the smallest unit
of information in the digital world. A single
bit can hold only one of two values 0 or 1.
(On or Off) A bit-mapped image is made up of
dots. A dot is a single point, the smallest
identifiable part of an image. Image files are
often described by the number of bits used to
represent each dot or pixel.
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Bit depth -- also called pixel depth or color
depth -- measures how much color information is
available to display or print each pixel in an
image. Greater bit depth (more bits of
information per pixel) means more available
colors and more accurate color representation in
the digital image.
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• A 1-bit image is monochrome, each dot is either
  on or off hence the image is only rendered in
  black and white, with no shades of gray.
• An 8-bit image supports 256 grayscales or 256
  colors.

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256?????
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256?????
2x2x2x2x2x2x2x2 256 or 2 to the power of 8
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256?????
2x2x2x2x2x2x2x2 256 or 2 to the power of 8 We
often call an RGB image 8-bit. Actually it is
8-bits per color channel (8x3).
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This is also referred to as a 24-bit image. Each
dot or pixel is represented by 24 bits. Using 24
bits means that more than 16 million unique
colors can be represented. Since humans can only
distinguish a few million colors, this is more
than enough to accurately represent a color
image.
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• A 16-bit per channel image actually has 48 bits
  (16x3) of color information in each pixel. A 48
  bit image is capable of billions of colors. This
  is available with RAW files and high end cameras.

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• RESOLUTION
• or REZ for short

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• A camera that captures 1600 x 1200 pixels
  produces an image with a resolution of 1.92
  million pixels and would be referred to as a 2.0
  megapixel camera.
• You get to 1.92 million pixels by multiplying the
  vertical and horizontal dimensions. That number
  is then rounded off to 2 for marketing purposes.

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• There is true resolution and interpolation.
  Interpolation is the process of "sizing up" a
  digital image by adding pixels that were not
  there originally.
• Since every pixel must have a color, this process
  usually involves assigning an intermediate color
  to the "invented" pixels based upon the colors of
  the pre-existing pixels surrounding the new ones.

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• The result is a larger image in terms of
  resolution, but one that now has less clarity
  because you simply cannot produce something from
  nothing.

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• Need more info?
• On-line resources
• http//www.vividlight.com/Articles/3116.htm
• Textbook pages 15 - 25

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• Exposure
• When light is allowed to pass through the lens,
  and through the opened shutter curtain in the
  camera, you have exposed light to the film (CCD,
  CMOS, or Foveon sensor with digital). The amount
  of light you allow to reach the film or sensor is
  a result of two basic functions, aperture and
  shutter speed both play a part in creating an
  exposure.

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• Aperture
• The size of the opening in a lens through which
  light passes is controlled by the aperture
  setting. It controls the volume of light
  transmitted to your film or sensor, in terms of
  stops such as f/2.8, f/4, f/5.6, f/8 and so
  forth. 

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• Shutter Speed
• The duration of time that the shutter curtain is
  open in your camera, allowing light to hit the
  film or sensor is controlled by shutter speed.
  This is reflected in the fractional term such as
  1/30th of a second, 1/60th, 1/125th, 1/250th and
  so forth.
• 4. Correct Exposure The proper combination of
  aperture and shutter speed to get the results you
  desire is correct exposure. 
• 5. Bracketing The over- or under-exposing of the
  camera's metered choice for correct exposure. How
  much or how far you bracket is up to you, i.e.,
  1/3, 1/2, or 1 full stop, for example.

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• So.
• Aperture controls how much.
• Shutter speed controls how long. 
• The proper combination of aperture and shutter
  speed to get the results you desire is correct
  exposure. 

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• Bracketing
• The over- or under-exposing of the camera's
  metered choice for correct exposure. How much or
  how far you bracket is up to you, i.e., 1/3, 1/2,
  or 1 full stop, for example.

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• With a film camera you change the type of film in
  order to match the type of light you're
  photographing in. With a digital camera you
  adjust the white balance to match the light that
  you're shooting in.