Images

Images

1. Bitmap

   • Bitmap images are stored as an array of pixels (picture elements)
     • The number of pixels in an image is shown by its resolution
       • The resolution shows how many pixels across and how many pixels up the image has, you calculate the total number of pixels by multiplying the across pixels by the up pixels - 1080 x 720
   • In a black and white bitmap image each pixel is stored as 1 bit, white being 1 and black being 0
   • A colour bitmap image is stored by replacing the 1s and 0s with a longer number that represents what colour that pixel is
     • These files will be a larger size than black and white images
     • The more bits per pixel the more colours that are available to use but also the larger the file size is
       • With 8 Bits or 1 Byte you can store 256 colours and 9 bits you can store double that etc.
   • The larger the size of a bitmap file depends on how many colours you can have per pixel and how many pixels there are
     • To calculate the size of a bitmap file you multiply the resolution by the number of bits per pixel
       • If you have a picture of resolution 1920 x 1080 and each pixel is stored as 1 byte,you would multiply the three together to get the size of the file = 1920 x 1080 x 8 = 16588800 bits, 2073600 bytes, 2073.6 kb etc.

2. Vector images

   • They use mathematical expressions to create the picture
   • They can be scaled up as they use formula to generate the image
   • The file size is significantly reduced
     • This means that they load on a webpage or in an image displayer faster
   • You give the colour, size, shape, fill and the start and end co-ordinates from the origin
   • The image is created by generating a series of mathematical curves

3. Meta data

   • Meta data is "Data about Data"
   • It is used for example on a webpage, it tells he computer what language it was written in, when it was created, who created it etc.