CS101.Lect15.Images.Compression.ppt

CS101.Lect15.Images.Compression.ppt - CS101 Lecture 15:...

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Computer Science CS101 Lecture 15: Image Compression Vector Graphics Compression Techniques Aaron Stevens (azs@bu.edu) 13 October 2011 Computer Science What You’ll Learn Today Review: how big are image files? How can we make image files smaller? What are the main image file formats, and how are they different from each other? What are the main techniques for compressing images?
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Computer Science Image File Size: HUGE! Raster/Bitmap Graphics Storage of data on a pixel-by-pixel basis Bitmap (BMP), GIF, JPEG, and PNG, for example How much data is required to represent a picture? Typical size might be 1024 by 768 pixels (~ 800,000) At 3 bytes per pixel, about 2,400,000 bytes for one picture. A 10Mpixel picture would be 30,000,000 bytes per picture. Computer Science Consider download times… Example: A 10Mpixel picture would be 30,000,000 bytes This is 240,000,000 bits. Typical home cable modem downloads at 5 Mbits per second (5,000,000 bits per second). How long to download this picture? 240,000,000 / 5,000,000 = 48 seconds
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Describe this picture… This image was a homework assignment by a CS108 student, Spring 2008. Vector Graphics describes an image by coordinates, lines, geometric shapes and colors. Computer Science
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This note was uploaded on 12/16/2011 for the course CS 101 taught by Professor Stevens during the Fall '08 term at BU.

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CS101.Lect15.Images.Compression.ppt - CS101 Lecture 15:...

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