T2 - Characters and Images Flashcards
Uppercase and lowercase in binary
different binary values
When text is encoded and stored using ASCII,
each of the characters is assigned a denary character code,
represented + stored in the computer as binary.
A 7-bit character code (like ASCII) has
128 different characters that can be encoded
An 8-bit character code (like extended ASCII) has
256 different characters that can be encoded
A character set
- a set of letters, symbols and digits that can be represented by a computer:
types of character sets
ASCII
Unicode
Unicode
- To represent other characters for different languages, 16 bits 65 536 possible combinations
Types of image files:
Bitmap - uses pixels
JPG - uses pixels
GIF - moving one
PNG - low quality
TIFF - raw (high quality)
Vector - uses a formula to maintain qualities
SVG
Bitmap images
- made from pixels which each have a colour + binary number for this
Image resolution
= the concentration of pixels within a specific area
Colours in pixel
- Each pixel has a proportion
of red, green and blue = makes one colour
Increasing the number of colours in bitmap:
More bits per pixel
= more colour combinations
bit depth
- number of colours
Higher bit depth
= more variety of colours
Bit depth formula
= 2^n where n is bits
Gives number of colours used
Size of bitmap images formula
= w*h in pixels
In 32-bit colour what are the last 8 bits for?
Transparency channel:
32 bits per pixel 8 bits are given
-allow a background to show through
Image size in bits formula
: width * height * colour depth
Image size in bytes: formula
(width * height * colour depth) /8
Metadata:
Colour depth in bits per pixel
Resolution (Height and width in pixels)
Date created
Author
Pros of colour values being in hex:
easier to read/write = reduces errors
RGB value range:
0 to 255
each colour must be 8 bits to store range
bit number per RGB
3 * 8 = 24 bits
