readme

实现图像的jpeg无损压缩

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.
  
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Feedback to
-----------
The SPMG lab at the University of British Columbia:
ismaeil R. Ismaeil [e-mail]
Dr. Faouzi Kossentini [e-mail], or