JPEG Compression in Matlab Michael Christensen

Outline Motivation General Method Still to do…

Motivation Instruction Provide a simple example

Method Step 1 Shift by 27

2D Discrete Cosine Transform Method, Cont. Step 2 2D Discrete Cosine Transform

Method, Cont. . / Step 3 Quantization

Method, Cont. ( ) = −26, −3, 0, −3, −3, −6, 2, −4, 1, −4, 1, 1, 5, 1, 2, −1, 1, −1, 2, 0, 0, 0, 0, 0, −1, −1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

( ) Method, Cont. Shorten = ( ) −26, −3, 0, −3, −3, −6, 2, −4, 1, −4, 1, 1, 5, 1, 2, −1, 1, −1, 2, 0, 0, 0, 0, 0, −1, −1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 Shorten = −26, −3, 0, −3, −3, −6, 2, −4, 1, −4, 1, 1, 5, 1, 2, −1, 1, −1, 2, 0, 0, 0, 0, 0, −1, −1, EOB 101001110011101111110111010110101011101000011001101110101110101010101101011011101011011110110111010001101110001101111011011000110101010111011101001101111010111011000110011110111010101100110101101110101010011110101110101010

Method, Final File Headers, etc. + = Output File 101001110011101111110111010110101011101000011001101110101110101010101101011011101011011110110111010001101110001101111011011000110101010111011101001101111010111011000110011110111010101100110101101110101010011110101110101010 + = Output File

Still To Do… Input multiple file types Modifiable quantization matrix for variable compression rates JPEG file conversion back to uncompressed format