Image Data Compression WG

Spring 2004 Pre-Meeting Status Report May 12, 2003

Meeting May 17-19, Greenbelt MD

Chair: Pen-Shu Yeh

Goals and Deliverables• Specify an image compression

algorithm fulfilling identified space mission requirements

• Develop a subsequent recommendation together with the supporting information (performances, usage, reference software, …).

Present Status• The algorithm is based on a 3-level discrete

wavelet transform (DWT) followed by a bit plane encoder (BPE).

• The DWT is specified in two forms: one with floating-point transform kernels, the other with integer kernels. The latter will allow compression down to “lossless” mode.

• The algorithm offers attractive compromise between performance and complexity for onboard applications.

DWT Status• A final decision was made in January 2004 after

extensive simulation showing the integer 9/7 DWT has performance better than the 5/3 integer DWT. Thus the 9/7 integer DWT is specified along with a floating point 9/7 DWT. The latter gives the best performance with no mean-error bias at all rates.

• Theoretical optimal weights for the integer DWT image is derived. Several variations of this weight set have been used in simulation. The final selection of the weights will wait till the Spring meeting at Goddard Space Flight Center.

• Chapters 1-3 have been revised and are in good shape.

Status on BPE

• Chapter 4 has been revised based on action item studies performed in minor details of the algorithm. Figure, table and equation numbers will have to be further edited.

• Independent software development confirms completeness of the spec: JPL, GSFC, U. Idaho. Cross-check will be performed after Spring meeting after the header specification is fully agreed and software further developed to reflect the final specification.

Plans• Resolve minor details in Chapter 1-4. • Finalize WhiteBook and request MC for promotion to RED-1

two weeks after the meeting.• Review agency RIDS via email 3 months after RED-1 is

produced• Issue Red Book version 2 for agency review two months before

Fall meeting.• Review RIDS on RED-2 in the Fall meeting and request for

promotion to BLUE.• Produce draft Green Book for the Fall meeting• Produce two independent software implementations to check

interoperability and completeness of spec by next meeting.• Produce an open source reference software for compliance

testing and performance evaluation. Software will be made available at one agency’s ftp site.