OUDF103 – Graphics Used In Modern Day Computer Animation

Gif – An animated gif uses the same principles of the old stop motion method. Gif stands for (graphic information file format) often-pronounced JIF.

Gif is one of the main file formats used today along side JPEG for images used on the web. It consists of a compression devise called ‘LZW’ which is able to compress an image without the loss of quality. Unlike the JPEG the Gif has a limited range of colours with a pallet of just two hundred and fifty six, this can result in images looking very grainy, this makes the Gif format un-suitable for full colour images but good for more simple graphics such as logo’s with solid areas of colour. The compression format Lempel-Ziv-Welch (LZW) used in Gif files for lossless data compression was patented in 1985, the patents have since expired but did not stop the controversy between the patent holder Unisys and CompuServe. This resuted in the creation of the Portible Network Graphics (PNG) file format, by Compuserve. Since the creation of the PNG it is becoming widly popular as it has better compretion technologie and is not limiter to the standard 256 colours. The only dounside to the PNG is that it does not have mulitiple image support unlike the Gif so it is unable to to stream picture to create a muliti image format that is used to create animation. This is simiular to the older vertion of the Gif the 87a which did not have animation capabilites untill updated to the 89a or Gif.


Vector – Or other names such as geometric modelling or object-oriented graphics they are made up of block colour, which is worked out by mathematical equations. For example a vector file uses maths to work out how an image is made up, it uses something similar to x and y coordinate.


To work out the colour of this squre the computer would do an equation. X * Y = Colour of block. So there will be no loss of image quality if the block is enlarge because the block would still equil X*Y.  Rastor graphics are still use because vector graphics find it hard to cope with high detaied images with a wide use of colour and they often look very cartoony.


Raster – Rastor graphic  are made up of pixels, there are worked out using code. Unlick Vector, bitmap store its information for an object for every pixle; so say if the square above is 10 * 10 pixels there would be 100 pices if information.


To make up that squre using a raster format such as jpeg it would doe this: Pixel 1 = Blue and to find the blue it will have a separate code as there are many shades of blue so sky blue = B28738. Pixel 2 = Gray = G363623. So there is a lot more information to be stores.


Unlike Vector graphics Rastor have Quality loss, so when a image is increased in size the computor has to work out how many extra pixel to add and what colour they need to be. This is to compensate for the increase in size resulting in the image looking blocky.

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