Download presentation
Presentation is loading. Please wait.
Published byRandell Rogers Modified over 9 years ago
1
The human eye
2
What you see l L H
3
Cross Section through the Retina
4
20/20
5
The sensitivity of this class
6
How big of a picture? u Final size of the image (in) (a x b) u Required resolution (dpi) u Calculate total number of pixels: u a x dpi x b x dpi u Depth of color (B) (doc) u a x dpi x b x dpi x doc u Compression
7
How many words does a picture worth? bits, not Bytes divide by 8! Size of file Modem speed (Kbps) Parity check and package sizes. Picture Words
8
Example: one page of text u PICTURE u 10”x7” at 76 dpi = 404,320 pixels u b&w 1 bit/pixel u 404,320 bits 50 KB (BMP) u With GIF compression 30 KB u TEXT ( 850 words) u 45 lines/page (1½ lines at 12 points) u 80 char/line u 45x80 = 3600 char. 3.6 KB u 5 KB / 1000 words. BOTTOM LINE: don’t use pictures if they don’t say 10,000 words!.
9
See for yourself 850 Words Text Document 5K Same document as GIF 27K Same document as BMP 57K Same document as JPG 222K
10
Transmission times: 56 Kbps modem 56 K download 33 K upload Text Document 4K - uncompressed - modem compression helps Picture 32 K - compressed - modem compression slows
11
On-line conversions u http://www.resizenow.com/ u http://www.zamzar.com/
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.