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					Image Resolution
Understanding pixel dimension
Vector Graphics
• Resolution independent – can be scaled to
  any size without losing any detail
• Object-oriented graphics
• Made-up of vectors

Bitmap (Raster) Graphics
•Resolution Dependant – contain a FIXED number of
pixels (size of image is based on the image resolution)

•Made-up of pixels – each pixel (picture element) is
assigned a specific location and color value
Different Types of Resolution?
  1. Image Resolution (ppi) pixels per inch
     high resolution – 300 ppi or higher
     low resolution – 72 ppi
     Bitmap image contain a fixed # of pixels

  2. Monitor Resolution
     # of pixels per unit of length (ppi) on a
     monitor.
  3. Printer or Output Resolution
     # of ink dots per inch (dpi) produced by a
     laser printer
     (higher resolution printer & high resolution image generally
     produce the best quality print output)
Resolution & Image Size

 Resolution:
 # of pixels that describe an image and establish the
 details


 Pixel dimensions:
 # of pixels along the width & height of the image

 5X7 image at 300ppi resolution =
 pixel dimensions of 1500X2100
Resolution…
 • When we create or scan a digital image we
   are capturing pixel information


   • WE decide how much pixel information to
     capture by setting the resolution as we scan.

      • Scanners record the color value and brightness of
        each area of an image when scanned.

   • WE decide the pixel dimensions of an image we
     create in an image editing program.
What’s your output device?
 • We prepare images based on the output
   device.

 • Images for PRINT
   • Should have a higher resolution
   • Usually in CMYK color mode

 • Images for VIDEO
   • Usually have a lower pixel dimension
   • Use RGB color mode
Print Resolution
• Higher resolution images...
  • Contain more pixels
  • can reproduce more detail & subtle color
    transitions when printed
  • Have a larger file size
Print Resolution
• Printer resolution ( the number of ink dots
  per inch(printed) dpi

  • Laser printers can range from 600dpi to 1200dpi
    – even higher

  • Common resolution settings
     •   72DPI    monitor or web
     •   100DPI   300DPI printer
     •   200DPI   600DPI printer
     •   300DPI   1200DPI printer
Resolution for the Web?
• Web graphics – worry about pixel
  dimension rather than resolution…
• Image pixels map one-to-one with the
  display resolution of a monitor
• Monitor resolution varies by platform and
  user configuration
• Monitor resolutions
  • http://www.thecounter.com/stats/2006/Septemb
    er/res.php
    Resolution…




•   High resolution graphics – not needed online. They just
    appear larger on screen and take up more file size and
    bandwidth.
   Points to Remember
• To produce good quality images… must
  understand image dimension.
• We must create or edit the image size to be
  suitable for the way we will use it.
• Start with a good scan.
• If you plan to edit or scale the image in any
  way, start with a higher resolution image
  and optimize and compress image for web
  after all edits are complete.
Resources
 • Adobe Web Tech Curriculum
   Lesson 5.1: Graphics Basics
   http://www.adobe.com/education/instruction/we
   btech/CS2/unit_graphics1/gb_print.htm

 • Scanning Tips by Wayne Fulton
   http://www.scantips.com/

				
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