Photoshop
uses image files that have been bitmapped.
bitmapped =
the conversion of a continuous tone image into a series of tiny squares called pixels.
The smaller the squares = higher resolution = larger
file size
ppi Ð the
number of pixels per a unit of length (i.e.Éinch, centimeter), in an image
lpi Ð is
the screen frequency of a printers Half Tone Screen in terms of Lines Per
Inch
Note: When you
are printing on a commercial printer (i.e.ÉImagesetter or Laser
Printers) Scan or Photograph your images at 1.5 to 2 times the
Screen Frequency (lpi) used by the printer.
EX. If the printer you wish to use has a screen frequency of 133 lpi
you want your image to be set at 266 ppi (133 x 2) at the final print size. (i.e.É8.5Óx11Ó)
The dots that Inkjet
printers print on a page to create an image become ÔinvisibleÕ to the human eye
at 300ppi. 220ppi looks great to most people.
Pixel Dimensions Resolution Relative To Best
printable
image
size
320X240 Television 1
x 1.5 Ò
640x480 small
website 2
x 3 Ò
720x534 NTSC
DV/DVD 3
x 4.5 Ò
800x600 average
website / old displays 3.5
x 5 Ò
1024x768 large
website / 15Ó display 4
x 6 Ò
1152x864 5
x 7 Ò
1280x720 HDTV
720p 5
x 8.2 Ò
1600x1200 17Ó
display/ 2.1 mega-pixel 8
x 12 Ò
1712x1368 11
x 14 Ò
1920x1080 HDTV
1080i 6.4
x 15 Ò
2048x1800 16
x 20 Ò
2048x1536 19Ó
display/ 3.2 mega-pixel 20
x 30 Ò