4. What’s the difference between a digital
camera and a regular film camera?
• Film cameras depend on chemical and
mechanical processes
• Film cameras do not even need electricity
• Digital Cameras have a built in computer
which record images electronically
5. Digital camera and a Regular film camera
• A Digital Cameras has different
lenses that help focus the light
to create the images
• A 35 mm camera would focus
the light onto a piece of film….
• a Digital Cameras focus the
light onto a semi-conductor
device that records the light
electronically
– A computer breaks this info
down into digital data
6. What breaks down the info
into digital data?
• A sensor converts the light into
electrical charges
• Digital Cameras use CCDs (Charged
Couple Devices) or CMOS
(Complementary Metal Oxide
Semiconductor)
– Both convert light into electrons
– Value is read of each cell in the image
– Both operate similarly converting the light
into readable form
7.
8. CCD CMOS
• Although numerous differences exist
between the two sensors,
• They both play the same role in the
camera -- they turn light into electricity.
• To understand how a digital camera
works, you can think of them as nearly
identical devices.
9. What’s the real difference
• Because each pixel on a CMOS • CCD sensors create high-
sensor has several transistors quality, low-noise images.
located next to it, the light
sensitivity of a CMOS chip is
lower. • CMOS sensors are
generally more
• CMOS sensors traditionally susceptible to noise.
consume little power.
• CCD sensors have been
• CCDs, on the other hand, use a mass produced for a
process that consumes lots of longer period of time, so
power. they are more mature.
• CCDs consume as much as
100 times more power than an • They tend to have higher
equivalent CMOS sensor. quality pixels, and more of
them.
10. What else is important in a
Digital Cameras?
• Resolution
– The amount of detail that the camera can
capture and it is measured in pixels.
– The more pixels a camera has, the more
detail
– it can capture and the larger pictures can
be without becoming blurry or "grainy."
11. Common Resolutions
• 256x256 - Found on very cheap cameras, this resolution is so low that the picture
quality is almost always unacceptable. This is 65,000 total pixels.
• 640x480 - This is the low end on most "real" cameras. This resolution is ideal for e-
mailing pictures or posting pictures on a Web site.
• 1216x912 - This is a "megapixel" image size -- 1,109,000 total pixels -- good for
printing pictures.
• 1600x1200 - With almost 2 million total pixels, this is "high resolution." You can print
a 4x5 inch print taken at this resolution with the same quality that you would get
from a photo lab.
• 2240x1680 - Found on 4 megapixel cameras -- the current standard -- this allows
even larger printed photos, with good quality for prints up to 16x20 inches.
• 4064x2704 - A top-of-the-line digital camera with 11.1 megapixels takes pictures at
this resolution. At this setting, you can create 13.5x9 inch prints with no loss of
picture quality.
18. How do Digital Cameras
capture color?
• Photosets are blind
• Photosites only keep track of the total
intensity of light that strikes the surface
• To get full color of an image, most sensors
use filtering to look at the light in its three
primary colors
• All three colors get recorded and combined
to create the full spectrum
19. Exposure & Focus
• Digital camera has to control the amount
of light that reaches the sensor.
• The two components it uses to do this, the
aperture and shutter speed, and are also
present on conventional cameras.
20. Exposure & Focus
• Aperture: The size of the opening in the
camera.
– The aperture is automatic in most digital cameras, but
some allow manual adjustment to give professionals
and hobbyists more control over the final image.
• Shutter speed: The amount of time that light
can pass through the aperture.
– Unlike film, the light sensor in a digital camera can be
reset electronically, so digital cameras have a digital
shutter.
21. Exposure & Focus
• Aperture and shutter speed work together to
capture the right amount of light needed to
make a good image
• The camera also adjusts the lenses to control
how the light is focused on the sensor.
• Most Digital Cameras use auto focus lenses
22. Focal Length
• This is the biggest difference
between a digital camera and a
regular conventional camera
• So what is focal length…
– The distance between the lens and
the surface of the sensor
– This determines the magnification
(zoom)
– Increasing the focal length increases
the zoom / magnification and vice
versa
23. Digital Camera Lenses
• Fixed-focus, fixed-zoom lenses - These
are the kinds of lenses on disposable and
inexpensive film cameras -- inexpensive
and great for snapshots, but fairly limited.
24. Digital Camera Lenses
• Optical-zoom lenses with automatic focus -
Similar to the lens on a video camcorder, these
have "wide" and "telephoto" options and
automatic focus.
• The camera may or may not support manual
focus. These actually change the focal length of
the lens rather than just magnifying the
information that hits the sensor.
25. Digital Camera Lenses
• Replaceable lens systems - These are
similar to the replaceable lenses on a
35mm camera. Some digital cameras can
use 35mm camera lenses.
26. Storage
• Early generations of digital cameras had
fixed storage inside the camera.
• You needed to connect the camera directly
to a computer with cables to transfer the
images.
27. Storage
• Today's cameras are capable of
connecting through serial, parallel, SCSI,
USB or FireWire connections
• They usually also use some sort of
removable storage device.
28. Storage
• Removable storage devices include:
– Floppy disks
– Hard disks, or microdrives
– Writeable CDs and DVDs
34. Resolution
• Quality of the pictures on a screen, print, or
file
– DPI = dots per inch (printer)
– PPI = pixels per inch (screen)
• More resolution means higher file size
• Different file types contain more or less
information (resolution)
35. Understanding pixels
• Picture elements (dots) per inch
• Standard monitor displays 640 by 480 pixels
– 640 by 480
– 1024 by 768
• More pixels requires more RAM, which may
mean lower bit depth
