{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

compression

# compression - CS148 Introduction to Computer Graphics and...

This preview shows pages 1–12. Sign up to view the full content.

CS148: Introduction to Computer Graphics and Imaging Compression

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Key Concepts Lossless vs. lossy compression Kolmolgorev complexity Predictive coding / Hu f man coding JPEG / Discrete cosine transform (DCT) JPEG2000 / Wavelets
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Image and Video Data Rates Image 640x480x24b = ~3/4 MB Full screen Image 1024x768x24b = ~2.5MB DVD 720x480x24bx30f/s = ~30 MB/s High Deﬁnition DVD 1920x1080x24bx30f/s = ~178MB/s Film 4000x3000x36bx30f/s = ~1.5GB/s 8 TB for one 90 minute movie!

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Lossless vs. Lossy Compression Lossless All information stored Exact original can be reconstructed Lossy Some information discarded Goal: discard information humans won’t notice Much higher compression ratios possible
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Kolmogorov Complexity What is the shortest program that can generate the data? 17 KB JPEG Re(c), Im(c), xmin, xmax, ymin, ymax (24B) z 0 = x + iy z n +1 = z 2 n + c

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Run Length Encoding BWBBBBBBBBBBBBWWWWWWBBBW BW\{12}B\{6}W\{3}BW
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Code Book Alphabet: A, B, C, D Frequencies: ¼ , ¼ , ¼ , ¼ Code: 00, 01, 10, 11 ABCDBDAC = 8 characters 00 01 10 11 01 11 00 11 = 16 bits ¼ * 2 + ¼ * 2 + ¼ * 2 + ¼ * 2 = 2 bits/ch on average

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Code Book Alphabet: A, B, C, D Frequencies: ½ , ¼ , 1/8, 1/8 Code: 0, 10, 110, 111 ABACADAB = 8 characters 0 10 0 110 0 111 0 10 = 14 bits ½ * 1 + ¼ * 2 +1/8 * 3 +1/8 * 3 = 1 ¾ bits/ch on average
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Entropy

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Hu f man Coding A (.10) B (.15) C (.30) D (.16) E (.29)
CS148 Lecture 16 Pat Hanrahan, Winter 2009 Hu f man Coding A (.10) B (.15) C (.30) D (.16) E (.29) AB (.25) 0 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 45

compression - CS148 Introduction to Computer Graphics and...

This preview shows document pages 1 - 12. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online