8. Multimedia

• What are pixels?

  Dots or the points of light that make up a digital image
• What does the resolutiom of an image mean?

  The number and size of pixels in a given area of the image
• What two factors affect quality of an image?

  Resolution and colour depth
• How does high and low resolution affect an image?

  High resolution : image is made of lots of small pixels to give a sharp and detailed image

  Low Resolution : image is made of fewer , larger pixels. The image is blurry or lacks detail
• How does increased and reduced colour depth affect image quality?

  Increased colour depth : lots of different colour codes

  Reduced colour depth : fewer colour codes or just black and white
• What is the effect of high resolution combined with high colour depth?


  High quality image ; An image with lots of realistic colours and sharp details
• What is the effect of low resolution combined with decreased colour depth?

  Low quality image ; a blurry image or an image with few details using only a few simple colours
• Downside of a high quality image?

  File is larger
• What is metadata?

  Additional data stored withn the image to define:width,height,colour depth,colour palette etc
• What is bit depth?

  The number of bits used to represent each pixel in an image.
• What is colour depth?

  The number of bits used to represent the color of a single pixel in a digital image.
• What are sounds held as?

  number data
• Explain how sound is converted into a number code?


  Sound waves travel through air

  High frequency sounds higher in pitch , high amplitude sounds are louder

  Sound waves picked up by a digital microphone and turned into number codes
• What two factors affect sound quality?

  Sample rate

  Bit depth
• How does high and low sample rate affect sound quality?

  High sample rate : the sound is sampled more than a hundred thousand times per second by the microphone making it sound natural and realistic

  Low sample rate : sound is sampled less often so some subtle variations might be missed
• How does increased and reduced bit depth affect sound quality?

  Increased : lots of different sound codes are used adding to being realistic

  Reduced : fewer sound codes used so the sound is simplified
• High sample rate and increased bit depth effect?


  high quality sound ; when it is played back the sound is realistic and natural like real life
• Low sample rate and reduced bit depth effect?


  low quality sound ; sound is distorted or less realistic
• What is sample rate and what is it measured in?

  Sample rate is the number of samples of audio taken per second.

  It is measured in Hertz (Hz).

  44000Hz means 44000 samples per second
• Explain why a high quality sound file is larger in size?


  has more samples in it and each sample uses more bits making file size larger