JPEG and JPEG2000

Compression for Face Rec

Paul Griffin, CTOVincent Hsu, SenioScientistApril 2005
Introduction
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Outline

• Introduction: Performance vs. Co• Image Types Formats (Token and • Region of Interest (ROI) Compres• Compression and Match Performa• Recommendations
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Introduction

• The recognition performance degrades w

compression ratio increases.

• At some point, there may be a need to ov

to place a face image on a storage media

• To overcome this trade-off, region of inte

compression is preferable to preserve recperformance at file sizes.

• ROI compression is discussed in ANSI 38

annexes for both JPEG and JPEG2000.

• This analysis is based on the use of autom

match systems to measure performance 

• Note: the graphs in this presentation are 

Identix FaceIt identification SDK Generat

– Compression recommendations in ANSI 385 

Identix G5 
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Performance and JPEG Compr

• Performance loss (Normalized top rank) vs

Measurer ValuesIJG [5] JPEGQuality factor Q(1..100)

100 90 70 50 40 3

Compression Ratio T (T:1) 

6 21 42 58 66 7

Average File Size 

(KByte)

148.43 42.19 21.28 15.52 13.62 1

Top Rank (%) 100.00 98.79 98.31 98.07 97.35 9

Notes: Image file size and corresponding matching performance vary as corecognition performance is represented by the normalized top rank rate, wIdentification SDK G6 and the baseline JPEG compression of the IJG library, for th

Compression Ratio

20~25:1 (baselineJPEG, w/o noti

18:1 (baseline JPEG, 

2% degradation)

75:1 (JPEG 2% degradation
Image Types
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ANSI 385 Face Image Types

• Image Types:

– [1] “Biometric Data Interchange Formats—

Data,” Document number ISO/IEC CD 197INCITS 385-2004)

Basic

Frontal Other

Full Token

Image Types and Their Inheritance 
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NIST Mugshot Face Image Ty

• 480 (width) x 600 (height)• 18 Gray background• 3-point lighting• JPEG• Closest ANSI 385 Image Type is t
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Token Image Format

• Token face image is used for this analysis:

• Token 120 close to mug shot best 

practices specifications

• Height=640 vs. height=600 

Mugshot

• Easier to evaluate compression vs. 

performance independent of original digital image resolution via resampling

• Able to perform face-specific ROI 

compression since face position is well-defined.

Width Distance from Eye to Eye (Inclusive)

60120180

240480720

(0,0)

Recommended Width Variables 
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Regions of Interest

• Regions of Interest - Token or Mugsh(a) Two regions: Outer (background) Region and 

Inner (hair – chin - neck).

(b) Three regions

Core (foreheaRegion.
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Regions of Interest (Cont’d)

• Three Regions of Interest
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ROI Compression—JPEG 

• Re-quantization of Regions of High Comp

– To avoid the grainy artefacts, one selects hig

ratio quantization steps as an integer multiplcompression-ratio quantization steps

• ROI Compression at Limited File Size:

– New JPEG code can automatically search th

compression ratios for multiple regions

• Examples JPEG ROI compressed images:

155KB 5.8:1, Q100

17KB 53:1, Q76 14KB 66:1, Q64 
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ROI Compression—JPEG2000

• JPEG2000 can also accomplish compressi

file sizes

• Transition from region to region is much • Examples of JPEG 2000 ROI compressed 

99KB 9:1

17KB 53:1

14KB 66:1 
Compression a

Performance 
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Data Analysis

• Databases 

– Australia passport (1000 gallery and 1000 pr– FERET High Resolution set (1364 gallery and 

images)

– XM2VTS (295 gallery and 885 probe images)

• Compression of Images after conversion 

– Gallery sets: the uncompressed token image

at increasing compression ratios using the bcompression, and at file size limits of 75KB, 22KB, 17KB, 15KB, 14KB, 12KB, and 9KB.

– YUV 411 assures significant information in lu– Probe sets: uncompressed token images are 

compression ratio about 5.3:1 (i.e., 170KB).

• Examples shown on next few slides. For 

analysis, see reference listed at the end opresentation. 
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Rank 1 Performance

• Normalized Top Ranks
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Example ROC Performance 

• ROC curves
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Example: Grayscale VS. Color Im
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JPEG VS. JPEG 2000 – Normalized 
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JPEG VS. JPEG 2000 – Norma
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JPEG 2000 ROI Compression– Normalized ROC
Recommendat
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Recommendations — Compressio

The recommendations of compression for thRegions of Interest compression on YUV411 Images (keeping rank degradation within 1% measured databases, and <1% FRR increas

Single ROI 2 ROIs 

Max. Ratio

Min. Size

Max. Ratio

Min. Size

JPEG 20:1 45KB 20:1

120:1

30KB 

JPEG 2000 20:1 45KB 20:1

120:1

30KB 

ROI

Standards
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Examples 1,2,3 ROI

JPEGJPEG 2000

(Source 368KB) 45KB 30KB 
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Recommended Compression – Zo

45KB 30KB 17K

JPEG
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Recommended Compression – Zo

45KB 30KB 17K

JPEG2000
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ROI type and JPEG/JP2 verses S

50KB 20K

Limit of File Size (KB)

JPEG 1-ROI

JPEG 2-ROI

JPEG 3-ROI

30 

Better Visual Inspection

1-ROI

JPEG 1-ROI 

20

2-ROI or 3-ROI

JPEG ROI
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Summary

• Face recognition performance is a strong 

compression

• Therefore, maximum compression is dete

face recognition

• We studied token/mug shot images with 

distance of 120 pixels with JPEG or JPEG

compression. 

• A recursive search of compression ratios 

can meet a limit of file size for JPEG as w

JPEG2000.

• Use of multi-region compression improve

without compromising recognition.

• Minimum files sizes for both JPEG and JP

– 45 KB (1 region), 30 KB (2 region

(three region)

– Maximum central face compress

20:1
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For More Information

Paul.Griffin@Identix.comJPEG and JPEG2000 code available froJROI Web Page: http://www.identix.com

JROI Document: 

http://www.identix.com/research/JROI.

JROI Package: http://www.identix.com/research/JROI.

Presentation:

http://www.identix.com/research/JROI.
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JPEG Compression

• JPEG Standards:

– [2] “Digital Compression and Coding of Continu

Images, Requirements and Guidelines,” DocumT.81 or ISO/IEC 10918-1. 

– [3] “Digital Compression and Coding of Continu

Images, Compliance testing,” Document numbISO/IEC 10918-2.

– [4] “Digital Compression and Coding of Continu

Images, Extensions,” Document number ITU-T 10918-3.

• JPEG 2000 Standards:

– [5] “JPEG 2000 image coding system: Core cod

ISO/IEC 15444-1:2004 or ITU-T Rec. T.800.