COMPILATION INSTRUCTIONS:
1. Unpack archive.
2. Run
make clean "name",
where "name" is
loco -- for encoder/decoder
This program supports:
"8 bit" images with 8 bits per color component or less.
"16 bit" images with between 9 and 16 bits per color component.
component.
3. Executable for compressor is "locoe," decompressor is "locod".
USAGE:
General remarks for multiple-component images:
a) Encoder input (uncompressed) or decoder output (decompressed)
images are in either PGM (grayscale) or PPM (3-color) format.
This is of course NOT part of the JPEG-LS standard, and these
input/output formats were selected for this implementation only.
These formats have an ASCII header consisting of 3 lines of the
following form
* PGM (single component):
P5
cols rows
maxval
* PPM (3 components)
P6
cols rows
maxval
For PGM, the header is followed by cols*rows samples in binary
format, where cols and rows are the number of columns and rows,
respectively. A test image "cmpnd2g.pgm" is included in the
archive. Samples have 8 bits if maxval < 256, or 16 bits if
256 <= maxval < 65536.
For PPM, the header is followed by cols*rows TRIPLETS of symbols in
binary format. Each symbol in a triplet represents a color plane
value (viewers usually interpret PPM triplets as RGB).
For more than 3 components, the PPM output file
format is extended to arbitrary m-tuples,
where m is the number of components.
The first row of the header is Px, where x = 10+m
(e.g. P15 for a 5-component image). P5 (m=1), P6 (m=3),
and P7 (m=4) are used, in addition to P11, P13, and P14,
respectively.
A multi-component image can be specified to the encoder either
as a list of PGM files (each representing a color plane), or
a single PPM-type file.
b) Three modes of operation are supported for multi-component
images (images of the type RGB, CMYK, YUV, etc).
We briefly describe them now, for details see the
JPEG-LS Working Draft document.
* Plane-interleaved. The image components are
compressed one after the other, in a completely
independent form. Only multiple input
(one PGM file per plane) in the encoder, and multiple
output (one PGM file per plane) in the decoder are supported
in this mode. This mode also works when m=1.
* Line-interleaved. One row per image component is processed
at a time, in an interleaved form.
Common context statistics for all the components
are used in this mode, and is plane independent otherwise.
Both multiple PGM and single PPM input
(output) are supported in the encoder (decoder).
Line-interleaved mode is the default mode of the encoder.
This mode also works when m=1.
* Sample-interleaved mode. One sample per image component is
processed at a time, using common statistics. Only single PPM
input and single PPM output are supported in this mode.
c) Which of the three multi-components modes runs faster depends
on the specific system (UNIX or PC).
For the line interleaved mode, the processing time relation
between the single and the multiple files input/output depends
on the system as well.
d) Sub-sampled components can be specified to the encoder (e.g.,
a YUV representation with the U and V components having a fraction
of the number of columns of the Y component).
For sub-sampled files, the input to the encoder must be
given as a series of PGM files in non-increasing order of size.
Sample-interleaved mode is not supported for images with
sub-sampled components.
e) The output of the encoder, and input to the decoder, is
always a unique JPEG-LS compressed file, independently of the
number of image components. All the image components share the
same header in JPEG-LS.
COMMAND LINES:
encoder:
locoe [flags] infile1 [infile2,infile3,...] [-ooutfile]
DEFAULTS:
infile1 : must be in PGM or PPM format
infile2,... : additional input files for Plane Interleaved
or Line Interleaved modes. Must be in PGM (P5) format
outfile : default is locoe.out
FLAGS, PARAMETERS:
-i<infile> : alternate input-specification, use -i- for stdin
-o<outfile> : output specification, use -o- for stdout
-c : mode for multi-component images:
0: plane interleaved
1: line interleaved (Default)
2: sample interleaved
-n<error> or
-e<error> : Max allowed loss per symbol (default = 0, lossless).
-h : print help
Remarks:
The following optional flags allow specification of
parameters in the algorithm. These parameters,
if not default, are included in the JPEG-LS
header, and are part of the standard. Please
refer to Working Document for details.
-r : RESET (if not compiled with FIXRESET, see below)
-S<a,b,c> : Context modeling thresholds
-m<table> : Use mapping table where <table> is a file in the
format:
1st byte of <table> is the Table ID, 2nd byte
of <table> is the Width of each table entry (in bytes),
3rd - 6th byte of <table> is the Max Table Index Value
specified as an integer (4 bytes), 7th byte and on
are the table entries.
-t<num> : Use Restart Markers where <num> is the restart interval
(ie. number of MCU's between restart markers).\n");
*** Use only if you know what you are doing!
decoder:
locod [flags] [infile] [outfile1 [outfile2, ...]]
DEFAULTS:
infile = locoe.out
outfile1 = locod.out for single output file
outfile[1,2,...] = locod[1,2,...].out for multiple output files in
Plane or Line Interleaved mode
FLAGS, PARAMETERS:
outfile2, ... : multiple output specification for plane- or
line-interleaved mode
-i<infile> : alternate input specification, use -i- for stdin
-o<outfile> : alternate output specification, use -o- for stdout
-P : generate single (.ppm) output file for
sample/line-int. mode. Mandatory for sample-int. mode.
EXAMPLES:
For the examples, assume:
* red.pgm, green.pgm, and blue.pgm are 3 color components of
a color image, of the same size.
* color.ppm is the color image corresponding to red.pgm, green.pgm, blue.pgm
* hotely.pgm, hotelu.pgm, hotelv.pgm are 3 components of a color image
sub-sampled in the horizontal direction 2:1:1
a) locoe red.pgm green.pgm blue.pgm
Compresses the three files using the default color mode (line int., c=1)
Compressed file is in locoe.out
locod
Decompresses locoe.out into 3 pgm files:
locod1.out, locod2.out, locod3.out
locod locoe.out a.pgm b.pgm c.pgm
Decompresses locoe.out into 3 pgm files: a.pgm, b.pgm, c.pgm
locod -P
Decompresses locoe.out into one ppm file: locod.out
b) locoe color.ppm
Same as (a), using single input
c) locoe -c0 red.pgm green.pgm blue.pgm
Compresses the three files using the plane interleaved color mode
locod
Decompresses locoe.out into 3 pgm files: locod1.out, locod2.out,
locod3.out In this case, since c=0, the command locod -P will give
an error.
d) locoe -c2 color.ppm
Compresses color.ppm with sample int. mode. Note that only one (ppm) input
file must be given in this mode.
Output is in locoe.out
locod -P
Decompresses locoe.out into locod.out. Note that -P must be given, since
for sample int. mode, only single output file is supported.
g) locoe -Sa5 -Sb9 red.pgm
Compress red.pgm with Sa=5, Sb=9, and Sc=DEFAULT
h) locoe -r128 green.pgm
Compresses green.pgm with RESET=128.
OTHER CAVEATS, LIMITATIONS, ANNOYANCES, BUGS (?)
=================================================
* The makefiles included in this version are very simple and could lead to
a slower executable files than HP executables.
* Annoyance: no spaces are allowed between flags and their arguments. This
will be fixed in a future version.
* Other bugs, annoyances: you tell us.
------------------------------------------------------------------------------
Feedback to
-----------
The SPMG lab at the University of British Columbia:
ismaeil R. Ismaeil ismail@ee.ubc.ca
Dr. Faouzi Kossentini faouzi@ece.ubc.ca, or