Raster vs. Vector

Photos are raster-based images (rasters are small squares called pixels)

Photos

  • Measured in resolution
    • refers to the number of pixels that describe an image and establish its detail
    • determined by number of pixels along the width and height of an image
  • Think of resolution as depth of image quality
  • The higher the resolution the better the image quality

Resolution and size are inversely related

  • If physical size increases, resolution (quality) decreases
  • If physical size decreases, resolution (quality) increases

 

  • Resolution measured in ppi or dpi
  • Images on the Web should be 72 dpi
  • High-quality print images should be at least 300 dpi

 

Vectors

  • Vectors are mathematic (made of lines based on x-y coordinates)
  • No dots!!!
  • No matter how big you make a vector image, quality will not change!
  • Images can be made using vectors, but don’t have the same “true to life” quality as pixels
  • Although text can be made using pixels, text should always be made with vectors!!!!

 

Photoshop

  • Raster-based
  • Alter or create photos

 

InDesign and Illustrator

  • Vector based
  • Place photos & add text

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