Storing images

• What are images and sounds considered in data storage?

  Pieces of data stored on computers
• What are images made of in digital storage?

  Images are made of bits
• How do bits relate to your favorite songs in digital storage?

  Bits turn into your latest self-identified favorites
• How are images stored in digital format?

  • Stored as a series of pixels
  • Each pixel represents a color
  • Pixels are made up of bits
• What type of images do most users utilize?

  Bitmap images
• What are bitmap images composed of?

  Lots of tiny dots called pixels
• How is the color of each pixel represented?

  By a binary code
• What does the number of colors in an image relate to?

  It relates to the number of bits in the code
• How many colors do black-and-white images use?

  Two colors
• How many bits are needed for each pixel in black-and-white images?

  One bit
• How many colors can 2-bit images represent?

  Four colors
• What are the possible binary values for a pixel in a 2-bit image?

  00, 01, 10, and 11
• How many colors can a 4-bit image represent?

  Sixteen colors
• What is the total number of colors for a 24-bit image?

  16,777,216 colors
• What is the relationship between color depth and file size?

  Higher color depth increases file size
• What does increasing the number of bits per pixel do?

  It increases the range of colors and shades
• What is the image resolution?

  Number of pixels in the image
• How is image resolution often expressed?

  As width times height
• What happens to image quality with higher resolution?

  Better quality with more pixels
• What is the relationship between resolution and pixel count?

  Higher resolution means more pixels
• What is the effect of higher resolution on image detail?

  More detail in the image
• How many photoreceptor cells are estimated to be in the human eye?

  10 million
• What does image resolution refer to?

  Number of pixels in the image
• How is image resolution sometimes expressed?

  As width times height
• What happens to image quality with higher resolution?

  Quality improves with more pixels
• How do you calculate the file size of an image in bits?

  • Use the formula:

  $File size (in bits) =$$image resolution x color depth$

  • Color depth is often 8 bits per channel
• What is the formula to calculate the file size of an image?

  File size = resolution x color depth
• If an image has a resolution of $2000 \times 1000$ pixels and a color depth of 8 bits, what is the file size in bits?


  $16,000,000 \text{ bits}$
• How do you convert bits to bytes?

  Divide by 8
• If the file size is $16,000,000 \text{ bits}$, what is it in bytes?


  $2,000,000 \text{ bytes}$
• How do you convert bytes to megabytes?

  Divide by 1,000,000
• If the file size is $2,000,000 \text{ bytes}$, what is it in megabytes?


  $2 \text{ MB}$
• What is metadata in an image file?

  • Information stored in an image file
  • Helps recreate the image on screen
  • Includes format, dimensions, color depth, and resolution
• Why do devices need metadata to display images?

  To recreate the image on the screen
• What happens without metadata in image files?

  Devices cannot display the image
• What types of information does metadata usually include?

  • Image file format
  • Height and width
  • Color depth
  • Resolution