Final testttttt

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    • What is a digital image?
      A picture stored on a computer
    • What does it mean for an image to be digitised?
      It is changed into binary numbers
    • What is a pixel?
      A tiny square of colour
    • How do pixels form a digital image?
      Many pixels together create the image
    • What is a bitmap?
      A method for storing images using pixels
    • Why is it called a bitmap?
      It is a 'map' of where bits are stored
    • What does each pixel in an image represent?
      One colour
    • How are pixels stored?
      As binary values
    • How is colour depth measured?
      In bits
    • What does the number of bits in colour depth indicate?
      How many colours are available for each pixel
    • What is the colour depth of a black and white image?
      1 bit
    • What is one way to reduce the file size of an image?
      Compressing it
    • What are the advantages of reducing file size?
      Faster downloads and more storage capacity
    • What happens with lossy compression?
      Data is permanently removed from the file
    • What is a key characteristic of a decompressed file using lossy compression?
      It is an approximation of the original
    • How does lossless compression differ from lossy compression?
      There is no loss of data with lossless
    • What happens when a file compressed with lossless compression is decompressed?
      It is identical to the original
    • What does resolution measure?
      Pixel density
    • How is resolution usually measured?
      In dots per inch (dpi)
    • What is the relationship between the number of pixels and image resolution?
      More pixels mean higher resolution
    • How is image file size calculated?
      File Size = Resolution x Colour Depth
    • What is resolution in the context of image size?
      Total number of pixels in the image
    • In what units is image size typically written?
      Kilobytes or megabytes
    • What conversions are needed for image size calculations?
      Bits to bytes, bytes to KB or MB
    • colour depth chart
    • In a transposition cipher, the characters remain the same but are transposed (i.e. rearranged) in some way.
      The Route Cipher is a simple example of a transposition cipher.
        READ DOWN THE COLUMNS
      The Columnar Cipher is similar to the Route Cipher but introduces a key word as part of the key to control the order of the columns.
      1. Key word
      2. Order of letters
      3. Write out
      4. Columns in order
      Rail fence cipher
      Key = 4, letters go down by 4
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