Download Pixel

Terms 6
Definitions and Questions
Pixel, Megapixel, Webcam
Pixel: The basic unit of the composition of an image on a television
screen, computer monitor, or similar display.
An abbreviation of the term 'picture element.' A pixel is the smallest picture
element of a digital image. Like the fibers of a fabric, individual pixels are
too small to notice, but together they make up the whole. The smaller the
pixels, the higher the resolution. A display resolution described as being
640x480 has 640 pixels across the screen and 480 down the screen, for a
total of 307,200 pixels. The higher the number or pixels, the higher the
screen resolution.
Megapixel: The imaging term for an image sensor of one million pixels

or more. The higher geometric pixel resolution of these sensors
produce higher quality digital photographic images.
Webcam: A camera designed to take digital photographs and transmit
them over the Internet or other network.
Pixel, Megapixel, Webcam Q/A
Q: Is a 5 Megapixel camera always better
than a 3 Megapixel camera? Why or why
not?
A: No. See:
http://www.kenrockwell.com/tech/mpmyth.htm
http://www.majid.info/mylos/stories/2004/02/13/megapixel.html
http://megamyth.homestead.com/
Webcams
Q: Does IU run any webcams?
A: Yes. See
http://www.indiana.edu/~college/msb/webcam.php
and
http://registrar.iupui.edu/webcam/
Fixed Storage
Fixed storage is an internal storage
medium used by computers. The most
common type of fixed storage is an
internal hard drive.
Although fixed storage devices can be
removed from a computer for reasons
such as upgrading or repair, they typically
are not removed from the system.
Fixed storage capacities are usually in
gigabytes.
Removable Storage
Removable storage is a data storage medium that is
located outside of the computer.
Removable storage tends to come in three varieties:
magnetic (e.g. Zip disc), optical (e.g. CD-R/RW), and
solid-state (e.g. Flash memory).
Capacities of removable storage devices run from 1.44
MB for a floppy disc up to multiple gigabytes for external
hard drives. Removable storage devices also provide
conveniences such as the ability to make back-up copies
of data, transfer data between computers, and copy data
to give to someone else. Many MP3 players, digital
cameras, and PDAs use removable storage.
Removable Storage
Magnetic:
Microdrive
Solid-State:
SmartMedia Card
Removable/Fixed Storage Q/A
Q: How do removable storage and fixed storage
apply to things like digital cameras?
A: Most cameras now have both. They have a
small amount of fixed internal storage, and an
expansion slot to accept removable storage
media. This allows you to take pictures on fixed
storage if you don’t have an expansion card, but
to expand the memory if you do.
Removable Storage and Printers
Newer printers designed
for digital photo printing
have slots for removable
media. You can take
media with pictures out
of the camera, plug it
into the printer, and print
photos, without even
needing a computer.
Digital Photo Printer
Some of them also
have screens so
you can preview the
pictures.
This one takes 4
types of memory
cards: Compact
Flash, SD, xD, and
Memory Stick.
Flash Memory
A form of memory that allows multiple
memory locations to be erased or
written in one programming operation.
It is a form of rewritable memory chip
that holds its content without the need
of a power supply.
Flash memory gets its name because the microchip is
organized so that a section of memory cells are erased
in a single action or "flash."
Flash Memory Types
Secure Digital Card - The SD card's nimble, portable data transfer
and low battery consumption makes it ideal for high-speed digital
cameras, camcorders, MP3s, cell phones, PDAs, and global
positioning systems. Interface options include an SD interface or a
serial peripheral interface.
Memory Stick - Memory Stick is about the size of a stick of gum and
comes in many capacities. Memory Sticks can be used in an array
of applications, including video cameras, audio recorders, and
computers with a Memory Stick slot.
USB Flash Drive - A USB flash drive is essentially NAND-type flash
memory integrated with a USB 1.1 or 2.0 interface used as a small,
lightweight, removable data storage device of up to 16 GB. Can be
used with most USB memory devices and as a small, portable
computer hard drive.
Flash Memory Q/A
Q: These are 3 of the most common types of
flash memory cards. Can anyone identify them?
A
B
C
Flash Memory Q/A
A:
A
SD Card
B
C
Compact Flash Memory Stick
Other Types
USB Flash Drive
xD Card
 SmartMedia
Physical Size Comparison
USB Drives (Weird)
Lossy Compression
Refers to data compression techniques in which some
amount of data is lost. Lossy compression technologies
attempt to eliminate redundant or unnecessary
information. Most video compression technologies, such
as MPEG, use a lossy technique.
Lossless compression is a slower and less efficient
compression technique, but is often used for
spreadsheets or text files where the loss of words or
data would cause problems. Also, lossless algorithms
are easier to understand.
Zip File
A file that has been reduced in size to allow
faster transferring between computers, or to
save storage space. Originated with PKWARE,
the technique is widely used and the term is
used frequently to describe any compressed file.
Some compressed files have the .EXE
extension, indicating the file is self-extracting.
A file format used to compress PC computer
data into smaller files. Often used to speed up
Internet downloads.
Tar File
Short for tape archive, a UNIX utility that
combines a group of files into a single file. The
resulting file has a .tar extension. The tar
command does not compress files. Frequently,
therefore, a tar file is compressed with the
compress or gzip commands to create a file
with a .tar.gz or .tar.Z extension.
These are comparable to files that have been
compressed with WinZIP on a PC platform. Most
PC compression utilities, including PKZIP, can
open (untar) a tar file.
Lossy Compression Q/A
Q: MP3 and WAV are two audio formats. One
uses lossy compression and the other uses
lossless. Which is which?
A: WAV encoding is lossless. MP3 encoding is
lossy. This is why low-bitrate MP3s don’t sound
as good as CDs (WAV format). However, WAVs
are usually around 10x larger than MP3s,
making MP3s or similar compressed formats the
choice for portable audio and large collections.
Common ZIP/TAR File Q/A
Q: If I zip a file and then zip it again
repeatedly, will it keep getting smaller?
A: No. Eventually you hit a point where the
file is as small as it can be and still have
all the original data be recoverable. This is
because ZIP files are lossless encodings.
Common ZIP/TAR File Q/A
Q: I want to archive a large data file to CD
for backup. It’s 1 GB. CDs store 700 MB.
When I zip it, it goes down to 850 MB. Am
I out of luck for burning this file to CD?
A: No. Most ZIP utilities allow you to make
archive files that span multiple disks. So
you could store a ZIP file on several floppy
disks or CDs. To recreate the file, you will
then need all of these disks.
Quiz
Please put away your notes, take out a
sheet of paper and put your name and
today’s date on it.
Quiz
1. What has higher bandwidth, a T3 or a
T1?
2. The magnetic disks inside of hard drive
are known as ________.
3. Define VRAM.
4. Which is bigger, a bit or a byte?
Quiz
1. What has higher bandwidth, a T3 or a
T1? – a T3
2. The magnetic disks inside of hard drive
are known as _platters_.
3. Define VRAM. – Video Random Access
Memory
4. Which is bigger, a bit or a byte? – a byte
is 8 bits