Image representation - 87 - 91 Flashcards
how can images in computers be stored
as bitmaps or vectors
difference between bitmaps and vectors
- bitmaps use single discrete, individual pixels of colour, which make up image
- whereas a vector uses lists of information and mathematical equations to draw an image based on the data
how to calculate size of image in pixels
width in pixels x height in pixels
what is a pixel
every dot of colour in the image
what is resolution
width in pixels x height in pixels / number of dots per inch, where a dot is a pixel
- measured in pixels per inch
what is colour depth
number of bits stored for each
pixel.
- n bits gives 2^n combinations
How many bits are usually in modern images?
24
how to calculate storage requirement for bitmaps
height in pixels x width in pixels x colour depth
relationship between the quality, colour depth, and file size
as the quality and colour depth of an image increases, its file size increases
what is metadata
data about data
- is stored along with the actual bits which make up the image and increase the overall file size
examples of metadata
- dimensions
- colour depth
- width and height in pixels
- location
- creation date
- file name
examples of information needed to draw a vector image
- fill colour
- radius
- outline colour and width
- coordinates
advantages of vector graphics
- file size is kept relatively smalll, regardless of how much you scale the image
- will always scale without loss of quality
- good format for logos and images with simple shapes and colours
- they transmit faster and load quickly
disadvantages of vector graphics
- cannot easily replicate an image with continuous areas of changing colours
advantages of bitmapped graphics
- great format for storing full colour images taken on a phone or digital cameraas they can deal with images that have continuous areas of changing colour
- can manipulate individual pixels easily
- images can easily be altered or retouched
