Glossary pixels

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Glossary pixels

  1. 1. BTECLevel 3 Extended Diploma in Creative Media ProductionUnit 64: Motion Graphics and Compositing VideoThe term pixel is short forPicture element and pixelsare the small dots thatmake up the images ondigital. They are thesmallest addressableelement in a displaydevice. Each pixel can onlybe one colour at a time,but because they are sosmall they tend to blendtogether from differentshades and blends ofcolours .Pixels and ColourColour Depth: this is defined by the number of bits per pixel thatcan be shown on a computer screen. Data is stored in ‘bits’ each bitrepresents 2 colours as it has a value of either 0 or 1 and the morebits that there is per pixel the more colours that can be displayed.These are some examples of colour depth:Colour Depth Number of Colours1 bit colour 24 bit colour 168 bit colour 25624 bit colour True Colour: 16,777,216
  2. 2. Pixels and ColourBTECLevel 3 Extended Diploma in Creative Media ProductionUnit 64: Motion Graphics and Compositing VideoColour Depth- since each bit represents 2 different colours, its quite simple to work out thenumber of colours for the various colour depths because the number of the colours it could bewould be 2 to the power of the number of bits per pixel:Colour Depth of 4 bits would be 2 times itself 4 times:2x2x2x2 = 16 coloursColour Depth of 8 bits would be 2 times itself 8 times:2x2x2x2x2x2x2x2 = 256 coloursColour Depth of 24 bits would be 2 times itself 24 times:2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x2 = 16,777,216 colours
  3. 3. BTECLevel 3 Extended Diploma in Creative Media ProductionUnit 64: Motion Graphics and Compositing VideoDigital Cameras don’t have film instead they have a sensor and this sensor converts lightinto electrical charges.It takes the light andfocuses it through thelens onto this sensormade out of silicon It ismade up of a grid of tinyphotosites and thesephotosites are sensitiveto light. These photositesare usually referred to aspixels as it is acontraction of a pictureelement and there aremillions of individualpixels in the sensor of adigital camera.Each pixel on the sensor absorbs photons and releases electronsthrough something that is called the Photoelectric Effect.This is where electrons are emitted from metals and non metallicsolids liquids or gas as a consequence of their absorption of energyfrom electromagnetic radiation of short wavelength such asultraviolet light for example.
  4. 4. BTECLevel 3 Extended Diploma in Creative Media ProductionUnit 64: Motion Graphics and Compositing VideoCCD - this stands for charge-coupled device and it is the image sensor that is used by mostdigital cameras but some camera use CMOS which is complementary metal oxidesemiconductor technology instead and both of these image sensors convert light intoelectrons. Once the sensor converts the light into electrons it reads the value of each cell inthe image. This electric charge is then transferred and converted to an analog voltage that isamplified and then sent to an analog digital converter where it is turned into a number -digitised.

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