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JBIG-KIT revision history
-------------------------

Changes in version 2.0 (2008-08-30)

Main new features of release 2.0:

- This release adds a separate lightweight "T.85" version of the
    encoder and decoder library (jbig85.c, jbig85.h). This new T.85
    library is optimized for embedded low-memory applications, such as
    printers and fax machines. It implements only the subset of the
    JBIG standard that is required by the ITU-T T.85 fax profile,
    namely only a single bit plane (P = 1) and no differential layers
    (DL = D = HITOLO = SEQ = ILEAVE = SMID = TPDON = DPON = DPON =
    DPLAST = 0) and some other restrictions (MY = 0, MX < 128).

The T.85 library requires only three pixel rows of the
    uncompressed image to reside in memory at any time. This 3-line
    buffer has to be allocated by the calling application, therefore
    the T.85 library will not call any heap management functions such
    as malloc() or free() itself.

- There are also two new example applications pbmtojbg85 and
    jbgtopbm85 included that provide command-line access to the new
    T.85 library. (Note to distribution maintainers: there is probably
    little point in adding pbmtojbg85 and jbgtopbm85 to precompiled
    JBIG-KIT packages for workstation operating systems, as these two
    programs do not really provide the end user much additional
    functionality beyond what pbmtojbg and jbgtopbm already do, which
    use the full library instead.)

Changes to the original full jbig.c library from version 1.6:

- the arithmetic codec routines are now located in a separate source
    file (they are now used by both the full library jbig.c and the new
    T.85 library jbig85.c, and might also be of use to other applications)

- arithmetic decoder behaviour slightly changed to enable the
    lookahead needed to handle T.85-style NEWLEN after the final
    stripe

- added encoder support for adding comment marker segment

- added encoder option for using SDRST marker instead of SDNORM
    (only useful to make encoder able to generate a wider range
    of test data)

- added pbmtojbg options -C and -r, which provide command-line
    access to the previous two extensions

- slightly improved diagnostic output of jbgtopbm option -d

- non-English translations of error messages are now provided
    in a separate PO file (e.g., for use with GNU gettext),
    jbg_strerror() no longer has a language attribute and the
    JBG_EN, JBG_DE_8859_1, JBG_DE_UTF_8 constants no longer exist

- jbg_dec_in() return values changed; the least significant bits of
    the error codes now provide more information about what caused the
    error, beyond what the more general error text messages returned by
    jbg_strerror() reveal

- pbmtojbg has a new option -f as a shortcut for all the options
    needed to make the output comply to the basic ITU-T T.85 fax
    profile

- jbg_dec_getwidth(), jbg_dec_getheight(), jbg_dec_getsize(), and
    jbg_dec_getsize_merged() return now an unsigned long value
    (was: long), and return 0 (was: -1) if no image is available yet

- jbgtopbm now outputs image dimensions in header padded to 10
    digits fixed width, for consistency with jbgtopbm85
    to allow for later in-place update of height due to NEWLEN

- macro JBG_LICENCE can be changed from the default value "GPL" to a
    licence agreement reference code to if the library is used under a
    commercial licence, to clarify under which exact licence the
    library is used in a particular application

Changes in version 1.6 (2004-06-11)

- various small changes to reduce the risk of 32-bit unsigned
    integer overflows when dealing with extremely large images

- robuster treatment of L0 = 0xffffffff

- minor API modification in jbg_enc_options(): parameter l0 changed
    from type long to unsigned long; previous value now remains
    unchanged when l0 == 0 (was: l0 < 0)

- lots of type casts added such that the C source code is now
    also compilable as C++

Changes in version 1.5 (2003-06-11)

- fixed two minor memory leaks (special thanks to Davide Pizzolato
    <ing.davide.pizzolato@libero.it> for locating one of these)

- jbgtopbm does not attempt any more to parse multiple concatenated
    BIEs (options -m must be used now to enable this feature explicitly),
    in order to handle BIEs with data after the last expected SDE gracefully

- various extensions to improve support of JBIG fax applications
    (ITU-T T.85 profile):

o support for maximum adaptive template pixel offset increased
        to MX=127 in both encoder and decoder

o encoder now has a hook for producing BIEs with a NEWLEN marker
        segment and VLENGTH=1, in order to assist in testing decoders
        for T.85 conformance (see also new pbmtojbg option -Y)

o a new function jbg_newlen() can be used to scan an
        entire in-memory BIE for NEWLEN marker segments and update the
        YD value in the BIE header, which can be applied to BIE data
        before passing it to the decoder for T.85 compliance
        (Background: the incremental design of the JBIG-KIT decoder
        makes it infeasible to look ahead for NEWLEN marker segments
        that occur after the SDE with the last image line, therefore
        this second pass is necessary to handle the old-style fax
        applications permitted by T.85 in which the low-RAM encoder
        doesn't know the height of the image at the start of
        transmission)

Changes in version 1.4 (2002-04-09)

- typo fixed in stripe number calculation, which caused encoder and
    decoder to fail on certain image sizes (special thanks to Koen Denecker
    <denecker@elis.rug.ac.be> for locating this one)

Changes in version 1.3 (2002-03-23):

- bugs fixed in jbg_split_planes(), jbg_dec_merge_planes() that
    caused a failure for more than eight planes per pixel

- example converters now can handle PGM files with up to 32 bits
    per pixel

Changes in version 1.2 (2000-04-08):

- bug in the decoder fixed, which caused the rest of the input file
    to be skipped whenever a comment marker was encountered (special
    thanks to Ben Rudiak-Gould <benrg@math.berkeley.edu> for
    reporting this one)

Changes in version 1.1 (1999-11-16):

- serious bug in the encoder fixed, which for a very small
    percentage of images has caused an unterminated linked list to be
    created internally that could have been responsible for
    segmentation violations or non-terminating encoders
    (special thanks to Hisashi Saiga <saiga@itl.tnr.sharp.co.jp> for
    tracking that one down)

- minor bug in the "jbgtopbm -d" diagnostic output fixed

Changes in version 1.0 (1998-04-11):

- two bugs fixed that caused the encoder and decoder to fail
    under certain modes of operation with several bit planes

- added new functions jbg_split_planes(), jbg_dec_merge_planes(),
    and jbg_dec_getsize_merged() for easy handling of grayscale
    images

- added support for compressing grayscale PGM files to pbmtojbg
    and jbgtopbm

- more changes to avoid paranoid compiler warnings

Changes in version 0.9 (1996-01-09):

- encoder won't break any more on input bitmap data with incorrect
    zero padding

- pbmtojbg displays a warning if input file has incorrect zero
    padding

- various minor improvements suggested by Stefan Willer
    <Stefan.Willer@unnet.wupper.DE>

- many minor changes in order to avoid warnings from paranoid
    compilers

Changes in version 0.8 (1995-09-20):

- namespace cleared up, all names externally visible from the library
    start now with jbg_ or JBG_

- minor non-critical bug fixed which caused library to fail compatibility
    test and showed up especially on DEC Alpha systems

- jbg_dec_gethight() is now called jbg_dec_getheight()

- filenames conform now to MS-DOS limits

- Bug in pbmtojbg fixed (handling of ASCII PBM files)

Changes in version 0.7 (1995-06-10):

- more problems on 16-bit int systems and on Macintosh systems fixed
    (special thanks to Jean-Pierre Gachen <jpg11@calvanet.calvacom.fr>)

- global Makefile

Changes in version 0.6 (1995-06-08):

- memory leak fixed

- should now also work on systems where int is only 16-bit large

- changes of the JBIG "Technical Corrigendum 1" included (special
    thanks to Dr. Sebestyen from Siemens AG for sending me a copy
    of the draft)

First release: version 0.5 (1995-05-28)

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