1. MDDSP Literature Survey Presentation Eric Heinen
A Comparison of Still-Image Compression Standards and Proposed Methods for Improving Lossy Image Quality
MDDSP Literature Survey Presentation
Eric Heinen

2. Project Goals
Investigate existing methods for improving JPEG image quality
Consider adapting these methods to JPEG2000
Novel approaches?
Compare image quality of JPEG and JPEG2000 (with & without improvements) across
Image set
Compression ratios

3. Joint Thresholding and Quantizer Selection for JPEG Encoding (M
Joint Thresholding and Quantizer Selection for JPEG Encoding (M. Crouse and K. Ramchandran, 1997)
Optimize encoding without affecting decoding
Rate-Distortion optimization framework

4. Improved JPEG Compression Using Human Visual System (HVS) Model (G
Improved JPEG Compression Using Human Visual System (HVS) Model (G. Sreelekha and P. S. Sathidevi, 2005)
Exploits contrast sensitivity of HVS
Sinusoid at given frequency requires certain amount of contrast to elicit a response
HVS is insensitive to very low and very high frequencies
Contrast Sensitivity Function (CSF)
CSF Thresholding
Discard DCT coefficients below CSF value

5. Improved JPEG Compression Using Human Visual System (HVS) Model (G
Improved JPEG Compression Using Human Visual System (HVS) Model (G. Sreelekha and P. S. Sathidevi, 2005)
Also exploits masking property of HVS
Vision less sensitive to local variation in brighter regions
Compute luminance masking threshold based on block’s DC coefficient
DCT coefficients below this threshold discarded
Quantization after thresholding
different from JPEG standard
incompatible with JPEG standard decoder

6. JPEG2000 vs. JPG Arbitrary rectangular tile size allowed
Color space transformation can be
Lossless (YUV)
or lossy (YCbCr)
Discrete Wavelet Transform (DWT)
More sophisticated entropy encoding
Improvements to JPEG can be applied

7. Image Quality Assessment
Full-reference image quality metrics (IQM)
Estimate DMOS
Convenient
Popular IQMs
Peak Signal to Noise Ratio (PSNR)
Universal Image Quality Index
Structural Similarity (SSIM)

8. Statistical Evaluation of Recent IQMs (H. R. Sheikh, M. F. Sabir, and A. C. Bovik, 2006)
Image database
Set of distortions
JPEG, JPEG2000, White Noise, Gaussian Blur, simulated wireless channel
Collect mean opinion scores
3 different performance metrics
RMSE between IQM score and DMOS after non-linear regression
IQM
RMSE
PSNR
JND
DCTune
PQS
NQM
Fuzzy S7
BSDM (S4)
9.7934
SSIM (MS)
9.3691
IFC
9.0007
VIF
8.2459

9. Questions?