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JPEG Compression in Matlab. Michael Christensen. Outline. Motivation General Method Still to do…. Motivation. Instruction Provide a simple example. Method. Step 1. Shift by 2 7. Method, Cont. Step 2. 2D Discrete Cosine Transform. Method, Cont. . /. Step 3. Quantization.
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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
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. ( ) −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. 101001110011101111110111010110101011101000011001101110101110101010101101011011101011011110110111010001101110001101111011011000110101010111011101001101111010111011000110011110111010101100110101101110101010011110101110101010 + = Output File
Still To Do… • Input multiple file types • Modifiable quantization matrix for variable compression rates • JPEG file conversion back to uncompressed format