1. JPEG Compression in Matlab
Michael Christensen

2. Outline
Motivation
General Method
Still to do…

3. Motivation
Instruction
Provide a simple example

4. Method
Step 1
Shift by 27

5. 2D Discrete Cosine Transform
Method, Cont.
Step 2
2D Discrete Cosine Transform

6. Method, Cont.
. /
Step 3
Quantization

7. 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

8. ( ) 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

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

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