lecture notes

lecture notes 9-16-14

-gif worst for printing artwork

-compression=smaller file size but worse (sound or looks)

ex cd–sound quality between cd and iTunes 

movie on Netflix=compressed file

-all computer doc/files diff formats

-format determined by files origin 

ex software program like photoshop, or digital camera

-graphic files like photos/ video can be reduce in size

lossy or lossless 

-graphic image formats under 2 categories lossless and lossly

-with lossy data is lost, reduced for smaller sizes–poor image quality

-pixilation

ex jpeg gif

-lossless retains image for higher quality but larger file sizes

ex tif (for printing, magazines, business cards)

-raw file formats camera can take picture with no compression– save to diff formate (tif)

Graphic formates

-TIF, JPG, and GIF 3 most common formats for activities printing and displaying images over the internet

-PNG common web format, high quality can contain alpha (transparency) channel

-each format has own advantages and disadvantages 

black areas as transparent, white as opaque 

file formar tif

stands for Tagged Image Format

common format for desktop publishing

is lossless file formate

can result in larger file sizes not for internet

JPG

-Joint Photographers Expert Group

-created for digital photos and works best for photo content

-is lossly format 

-can reduce image file by 10;1 w/out showing significant compression artifacts

-level of compression is adjustable

gif made for flat color–choice

jpg for photos–don't save cartoons to JPG

GIF 

graphic interchange format

best for images with flat color or even tone, cartoons

reduce image bi "indexing" color from 3 channels to 1

is adjustable by changing color bit levels from 1 to 8

contains no DPI dots per inch data for printing. not a proper format for printing

can be animated–different durations for each frame

RGB

r=0-255

g=0-255 >I

b=0-255

know your pixels

TIF and JPG best for images with pixels that blend in color "contiguous pixels"

GIF best for "noncontiguous pixels"

Alias vs anti aliase

-pixels    -blends pixels

print=TIF

web=jpg

web=gif