Definitions

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Definitions

  1. 1. PixelPixels are essentially samples of an original image. They are the smallest element in a display device such asan LCD screen in which the image displayed on the screen is made up of a very large number of pixels puttogether. Pixels can be a measurement of resolutionfor example resolution of an image can be classedas 2400 pixels per inch or spaced x number of pixelsapart. It is most commonly described as twonumbers for example a resolution of 640 by 480meaning simply that there are 640 pixels from leftto right and 480 from top to bottom. This wouldtherefore indicate that the total number of pixels inthe image is 640 x 480 = a total of 307,200 pixelsResolutionResolution is simply the level of detail an image holds. The higher the resolution the more detail in the image.Resolution can apply to types of digital images, film images and many other types of media. With manydifferent media outlets resolution has a wide variety ofmeanings including things like pixel resolution and spectralresolution. The main definition of resolution when mediaimages are concerned is the quality of the image and howmany pixels are included. The image shown heredemonstrates different resolutions of an image shown in theorder of lowest to highest DPI (dots per inch).Screen ratiosThe basic concept of screen ratios or aspect ratio is the correlation between an images height and its width.The expression of aspect ratio is most commonly two numbers separated by a colon, e.g. 16:9 this is called anX:Y aspect ratio, for this to work the numbers donot specifically have to be the written number theyjust have to divide into x units of equal length andthe same with y. For example a group of imagesthat would all fit into the category of 16:9 couldconsist of an image of 16 inches by 9 inches, animage of 16cm by 9cm and even an image of 8 yardswide and 4.5 yards high. The image shown heredemonstrates some commonly used aspect ratiosThis demonstrates how aspect ratio is not used toshow the actual size of an object it is simply thedimensions.Frame rateTo get a good understanding of frame rate, first a brief understanding of the actual meaning of the wordframes must be established. Frames in this context is used to describe the brief sections in any motion image,such as computer graphics, film and pretty much any motion capture methods. The video only comes togetherto appear as though it is moving because of a large amount of pictures being projected at high speed. A frameis one of these pictures alone; so frame rate (or frames per second) is simply the rate at which the frames areprojected onto the screen. With this being the case, a high frame rate describes a video in which the framesare being projected one after another at a high speed, this makes the video appear smoother and flow well, aframe rate for this would be something like25fps which is the frame rate used for moststandard definition television broadcasts.
  2. 2. Video formatsCompressionCompression is a very useful tool for many different computer users with many different tasks to complete.Data compression, formally known as source coding is essentially the method of taking a file and using othersoftware to make the file much smaller but still contain the important elements for the file to run again.Unfortunately files can’t be compressed and then used andstored as smaller files; the file would need to bedecompressed in order to be run again. Data compressiondoes still have some obvious uses however such astransferring data and storing more data due to thereduced space those files need. Compressing data can beeither ‘lossy’ or ‘lossless’. Lossless compression reducesthe file size by finding and deleting redundancy in the file,which is essentially wasted space in the file. In thismethod of data compression no information is lost sotherefore this is the preferred method. Lossy compressionreduces the size by locating unnecessary information anddeleting it.

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