1. Pixel
• The word "pixel" was first
published in 1965 by
Frederic C. Billingsley of
JPL, to describe the picture
elements of video images
from space probes to the
Moon and Mars.
• Each pixel is a small
quantity of an original
image; more samples
typically provide more
accurate representations of
the original.

2. Pixels and Colour
• LCD pixels are
manufactured in a twodimensional grid, and are
often represented using
dots or squares, but CRT
pixels correspond to their
timing mechanisms and
sweep rates.
Colour Depth
1 bit colour
4 bit colour
8 bit colour
24 bit colour
No. Of Colours
2
16
256
16,777,216 or True Colour

3. Converting Light - Cameras
When a picture is taken there is a
small device inside which forms all the
similar colours and combines them to
make the picture and if you look
closely on any picture you will see
hundreds of small squares.

4. Resolution

5. The standard for screen displays is 72 PPI.
The standard for Print is 300 PPI.

6. Vector Images
• Vector (composed of paths)
• The vector graphics use mathematical
points connecting together to make up
the image
• Vector images is a lot clearer than
raster images

7. Raster Images
• Raster (composed of pixels) and
more commonly known as bitmap
images
• A Raster image uses a grid of
separate pixels which are each a
different colour and shade.
• A raster is a lot more blurry than
Vector images.

8. Antialiasing
• In computer
graphics, antialiasing is a
software technique for
diminishing jaggies - stair
step-like lines that should
be smooth. Jaggies occur
because the output
device, the monitor or
printer, doesn't have a
high enough resolution to
represent a smooth line.

9. Aspect Ratio
• The aspect ratio of an image is the
ratio of the width of the image to its
height
• Aspect ratio is expressed as two
numbers separated by a colon. That
is, for an x:y
• In objects of more than two
dimensions, such
as Hyperrectangles, the aspect
ratio can still be defined as the
ratio of the longest side to the
shortest side.