Help for RICE_DECOMP

Purpose

MIPS VICAR based application to decompress a compressed image using
RICE Adaptive Variable-length Coding, an algorithm developed by 
Robert F. Rice of JPL and implemented by Frank Rabe of the Technical 
University in Braunschweig, Germany for the Mars Pathfinder Lander IMP 
imaging system.

References

[1] Robert F. Rice, "Some Practical Universal Noiseless Coding Techniques, 
	Part III, Module PSI14,K+," JPL Publication 91-3, November 15, 1991.
[2] Chris Shinohara, "Imager for Mars Pathfinder Flight Software Compression
	Software Interface," University of Arizona, March 1994.
[3] Justin McNeill, "Proposed Keyword Names for Compressed/Decompressed Data
        for MIPS' Use", Interoffice Memorandum 384-94-017, February 8, 1994.
[4] Planetary Science Data Dictionary Document, JPL D-7116, Revision C, 
	November 20, 1992.
Execution

The command line call of this application is as follows:

RICE_DECOMP  INP="compressed image"  OUT="decompressed image" ['VERBOSE]

The input image is of the format defined by the application RICE_COMP.

Input Compressed Image Data Record Design

The compressed image data record is shown in the table below. Adjusting the 
values of segment size (VICAR parameter SEGMTSIZE) will cause the length 
of this record to change.  If all compressed blocks fit within one record, 
then only one record of 875 bytes is generated, packed with zeroes.
A compressed image file may contain multiple records.

		Table of Compressed Image Record Format

	Byte	Description
	-----------------------------------------------------------

	1	Starting block number in image
	
	2-876	Variable number of compressed image blocks totaling 
		less than 875 bytes

History Label Keywords for Decompressed Images

Below is a sample history label and following this are definitions of keywords 
to be used in the image labels to describe the data compression used. These 
are found in the compressed VICAR image history label for the task RICE_COMP.  

---- Task: RICE_COM -- User: jfm -- Wed Feb 22 15:25:55 1995 ----
ENCODING_MODE='LOSSLESS'
ENCODING_TYPE='Rice Adaptive Variable-length Coding (RICE)'
ENCODING_TYPE_DESCRIPTION=(
'This Rice Adaptive Variable-length Coding (RICE) uses predictive', 
'preprocessing and an adaptive variable-length coder to assign shorter', 
'code words to data values of higher probability and longer code words', 
'to data values of lesser probability. See Robert F. Rice "Some Practical', 
'Universal Noiseless Coding Techniques, Part III, Module PSI14,K+,"', 
'JPL Publication 91-3, November 15, 1991.')
IMAGE_LINES=32
IMAGE_LINE_SAMPLES=32
IMAGE_SAMPLE_BITS=8
BLOCKS=64
BLOCK_DIMENSIONS=(4, 4)
COMPRESSION_RATE=2.7421875
COMPRESSION_RATIO=2.909090909090909
SYNCHRONIZATION_INTERVAL=1024
START_OPTION=1
NUMBER_OF_OPTIONS=7
RECORDS=1
RECORD_BYTES=352
Description of Label Items

BLOCKS				(type INTEGER)
The total number of blocks used to spatially segment the image or data 
file prior to compression Blocks are rectangular areas of input. Each 
block of data is compressed separately. 

BLOCK_DIMENSIONS		(type INTEGER array of two elements)
The dimensions of a block for compression
The line dimension of the block is the first element of BLOCK_DIMENSIONS, 
followed by the sample dimension of the block.

COMPRESSION_RATE		(type DOUBLE PRECISION)
The average number of bits needed to represent a pixel or data number (DN) 
within a compressed image

COMPRESSION_RATIO		(type DOUBLE PRECISION)
The ratio in bytes of the original, uncompressed data file length to its 
compressed form. For example, a compression ratio of 5.00 means that on 
average, for every five bytes of input data, one byte of compressed data 
was generated by data compression.
ENCODING_MODE			(type CHARACTER ARRAY)
The mode of compression is either lossless or lossy, indicating the 
preservation or loss of information in the process of compression or encoding. 
For example, if the Discrete Cosine Transform is chosen with a selected 
quantizer, the encoding mode value would be LOSSY. The valid values are LOSSY 
or LOSSLESS.

ENCODING_TYPE			(type CHARACTER ARRAY)
The type of compression or encryption used for data storage
Contents of this value should be the full, unabbreviated, non-acronym name of 
coding or compression type. Examples of encoding types include but are not 
limited to Integer Cosine Transform (ICT), Block Truncation Coding (BTC), 
Discrete Cosine Transform (DCT), Joint Photographic Experts Group (JPEG) 
Standard DCT.

ENCODING_TYPE_DESCRIPTION	(type CHARACTER ARRAY)
Textual description of encoding type, which should include a reference to a 
journal paper, published text or some other publicly available, published 
material which definitively describes the encoding type.

IMAGE_LINES			(type INTEGER)
Total number of pixels along the vertical axis of the image prior to 
compression.
IMAGE_LINE_SAMLPES		(type INTEGER)
Total number of pixels along the horizontal axis of the image prior to
compression.

IMAGE_SAMPLE_BITS		(type INTEGER)
Indicates the store number of bits, or units of binary information,
contained in a IMAGE_LINE_SAMPLES value (uncompressed image bits per
pixel).

NUMBER_OF_OPTIONS 		(type INTEGER)
RICE compressor specific variable that has valid values between 2 and 
(data precision - start_option + 1).

RECORDS				(type INTEGER)
Total number of records containing compressed image blocks.
RECORD_BYTES			(type INTEGER array of "RECORDS" elements)
A array where each element contains the total number of bytes in each
record of compressed image block data.

START_OPTION			(type INTEGER)
RICE compressor specific variable that has valid values between 0 and
the data precision of pixels.

SYNCHRONIZATION_INTERVAL	(type INTEGER)
Total number of compressed blocks between sync counters.
History

Date written: 		July 1994
Platforms: 		VICAR portable software running on 
			Sun OS 4.1.3,Sun Solaris, and the SGI.
Revisions:		Original
Traceability:		MESUR Pathfinder Capabilities by Phase, D-11518.
			J. Wright, S. Roberts, February 1994.

Cognizant MIPS Engineer

Justin McNeill

Jet Propulsion Laboratory
MS 168-414
4800 Oak Grove Drive
Pasadena, California 91109

Phone:	818-354-7975
FAX:	818-393-6962
Email:	jfm@poconos.jpl.nasa.gov
Cognizant Mars Pathfinder Engineer

Frank Rabe
Technical University Braunschweig
IDA Institut fuer Dataenvaerarbeitungsanlagen
Hans-Sommer-Strausse 66
38106 Braunschweig Germany

Phone:	49-532-391-3742
FAX:	49-531-391-4587
Email:	rabe@ida.ing.tu-bs.de

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