
Version 9.04 (2011-08-05)

This is the fourth full release in the stable 9.x series.

This release includes fixes and solutions for a number of serious problems from
the earlier 9.x releases and so we strongly encourage those using earlier 9.x
releases to upgrade to this new version, to reap the benefits of those fixes.

In addition, those still using Ghostscript 8.71 and earlier should begin
migration to 9.x soon since many improvements, features and fixes from the 9.x
versions are impractical to back-port to these legacy versions.

Highlights in this release include:

  * Transition source base to git source control - not a big deal for most
    users, but an important change for those develop Ghostscript and GhostPDL.
  * This release introduces flexibility for controlling color based upon the
    graphic object type. In particular, it is now possible to specify unique
    output ICC profiles and rendering intents for vector graphic, image and tex
    portions of a document. It is also possible to override source color
    specifications and use specified ICC profiles and rendering intents for RGB
    and CMYK vector graphics, images and text portions of a document. Finally,
    DeviceGray source colors can now easily be specified to map either to K
    only or composite CMYK when the output device supports CMYK colorants.
  * New tiffscaled8 and tiffscaled24 devices. Add new tiffscaled8 and
    tiffscaled24 devices, copied and modified from tiffscaled. These output
    greyscale and 24bit rgb instead of tiffscaleds mono output. MinFeatureSize
    is ignored for these devices as it's meaningless for contone output.
    Downscaling is also now supported for png16m and pnggray, and a new
    pngmonod device has been implemented which uses grayscale rendering
    internally and then downscales/min_feature_sizes/error diffuses to
    monochrome.
  * The PDF interpreter will now try continue interpreting a PDF after
    encountering an error in a stream. The previous bevahior can be reinstated
    by passing -dPDFSTOPONERROR to Ghostscript.
  * Re-enable x11alpha as the default device on Unix systems, now that
    compatibility problems between anti-aliased output and transparency are
    resolved.
  * Update libjpeg to version 8c.
  * Experimental Text output/extraction device

    The txtwrite device has undergone some development, and now has genuine
    functionality. It accepts any input format which GhostPDL supports, and
    uses a combination of methods to try and determine the Unicode values for
    any text contained in the document.

    The code descends a hierarchy of methods in this process, starting with the
    most reliable and only falling back to less reliable methods when better
    methods fail. The current hierarchy is as follows:
     1. ToUnicode CMaps (PostScript or PDF) or GlyphNamesToUnicode tables
        (PostScript).
     2. Glyph names of the form 'unixxxx'.
     3. Glyph names defined in the Adobe Glyph List document.
     4. Input character code.

    Method 1 is highly reliable, method 4 is a best guess and not terribly
    reliable, though it will work for many files. It is probably most reliable
    for PostScript and PCL files.

    The device currently has one parameter 'TextFormat' which controls whether
    the output is Unicode text reflecting the layout of the original document
    (-dTextFormat=0) or a format intended for use by developers which includes
    the Unicode text and some formatting information, such as the size and
    position of the text, and the font in use (-dTextFormat=1).

    Note that his device does not do OCR (Optical Character Recognition) it is
    not capable of finding 'text' which is part of an image. However it will
    recover the 'invisible' text from PDF documents which have been scanned and
    OCR'ed by Acrobat for searching. Such text has a render mode of 3.

    This is the first release of this code and is very much an alpha release,
    we expect problems.

    In particular the TextFormat=0 output is likely to be incorrect, and will
    only work with top-to-bottom left-to-right text. It will probably also be
    confused by landscape documents printed on portrait media.

    TextFormat=1 should be more reliable, but there may be cases where text is
    dropped from the output. Text in PostScript documents using charpath is not
    yet supported for example.

    We do encourage feedback on the state of this device, and would be
    interested in hearing what kind of output would be useful for developers
    using TextFormat=1. For now, however, please do not raise bugs through
    Bugzilla, instead please send feedback to the gs-devel mailing list.
  * Experimental Unicode/UTF8 Support on Windows

    This release introduces some experimental build-time optional support for
    UNICODE pathnames on Windows. Essentially this works by following the model
    that Linux (and MacOS) have followed for years.

    If this code is enabled, then the way ghostscript handles command lines,
    registry settings, file accesses and other api calls with top bit set
    characters in (i.e. codes >= 128) will change. The net benefit of this
    change is that ghostscript will now be able to cope with accessing files
    with unicode characters (i.e. codes >= 256) in their pathnames.

    This behaviour is all completely transparent to users, with the exception
    of those calling the gsapi functions with strings including 'extended
    ascii' (i.e. characters with codes >= 128 and <= 255). These characters
    include accented latin characters, such as u + umlaut, a + grave etc. The
    changes required for code that is affected by this are relatively minor,
    but as this is a change to the current API, we are announcing it in
    advance, and inviting comments.

    As of the 9.04 release, the code is disabled. For those who wish to
    experiment you will need to build Ghostscript from source, and either pass
    USEUNICODE=1 when you invoke nmake or edit psi/msvc.mak to remove the /
    DWINDOWS_NO_UNICODE option from CFLAGS.

    WARNING: Our intention, subject to feedback, is to enable this by default
    in near-future releases (hopefully, the next major release). If you make
    use of the affected APIs you should be prepared for the change to occur -
    be aware, however, that the current code is experimental and, depending on
    the feedback we get, maybe subject to change.

    NOTE: this whole change refers to file paths, command line parameters and
    so on - it does not imply that we have unilaterally extended Postscript to
    understand UNICODE.
    More details:

    To give an example, suppose we have a file 'EXAMPLE' we'd like to invoke
    ghostscript on, where 'EXAMPLE' is actually a string that contains some
    characters with codes >= 128.

    On Linux (or MacOS X), when ghostscript is called from a shell, e.g.

    gs EXAMPLE

    the command is UTF8 encoded; this means that characters with codes < 128
    are left unchanged, and characters >= 128 are encoded into multiple bytes.
    This encoded string is then passed to the standard 'main' entrypoint in the
    gs executable.

    Ghostscript proceeds internally without any special handling of these
    multibyte characters at all. When it comes to access files it therefore
    passes out the UTF8 encoded strings to the standard OS file handling
    routines. These routines are designed to take pathnames in UTF8 format, and
    thus the files are accessed as normal.

    If the Ghostscript executable outputs these (or other) strings to its
    stdout, the shell again converts the output from UTF8 back to unicode in
    order to display it.

    The net effect is that the caller can seamlessly pass in unicode filenames,
    has his fileaccesses work out and gets unicode output without the core of
    ghostscript ever having to worry about it.

    The code change discussed here endeavours to make Windows follow the same
    pattern as closely as possible.

    When Windows executables are invoked, they can either be called through an
    'ascii' entrypoint (main), or through a unicode ('wide') entrypoint
    (wmain). The difference is invisible to the caller, except that unicode
    executables can accept characters >= 256 in their invocations.

    The new code changes ghostscript from being an ascii executable to being a
    unicode one. The Windows specific outer layer takes the unicode command
    string and UTF8 encodes it before passing it to the ghostscript core.

    Similarly, the Windows specific filing system calls are updated to accept
    utf8 encoded strings from the core, and to convert them to unicode before
    operating on them.

    The Windows gui app (gswin32.exe, NOT gswin32c.exe) is also updated to
    convert stdin/stdout between unicode and utf8 as appropriate, allowing
    unicode strings to be copied/pasted to/from other apps.

    All of this should be completely transparent to the user, and no code
    changes should be required. The one area where changes may be required are
    where ghostscript is invoked through the gsapi functions.

    Currently, on Linux (and MacOS X) any strings sent over the gsapi are
    assumed to be utf8 encoded (and thus can represent any Unicode character).
    On Windows, they are assumed simply to be in extended ASCII (and can
    therefore represent any character < 256 in the current codepage). With the
    proposed change, Windows will move to be in step with Linux. No differences
    will be caused to anyone who only uses chars <= 128, but those people using
    character codes between 128 and 256 (or indeed wanting to use higher codes)
    will need to utf8 encode the strings before calling gsapi functions.

    Such encoding/decoding is a very simple process, and code for both
    directions can be found in psi/dwmain.c, psi/dwmainc.c and psi/dwtext.c.

    Again, we welcome feedback on this feature, in this case problems or
    suggestions about the implementation can be submitted via Bugzilla but for
    detailed discussion about the approach for which we opted, it would be more
    beneficial discuss it (preferably) on our IRC channel #ghostscript on
    freenode.net, or on the gs-devel mailing list.

For a list of open issues, or to report problems, please visit
bugs.ghostscript.com.

Incompatible changes

Deprecated file "gs/base/errors.h" removed, psi/ierrors.h should be used
instead.

The eXternal Fonts (XFonts) functionality, marked as deprecated in 9.02 has now
been fully removed.

No other recorded incompatible changes.



    Version 9.02 (2011-03-30)

    This is the third release in the stable 9.x series.

    This is an "out of order" release, primarily to ensure the GPL Ghostscript
    release remains in version "lock-step" with the Artifex commercial release.

    Highlights in this release include:

    For monochrome devices, there is a new halftone technique for sampled image
    data. The existing technique is very efficient (and is is still used) for
    large areas of color, such as an area fill, but encountered performance
    problems dealing with sampled image data where a given colour value only
    covered a few pixels at a time. The new approach applies the halftone
    threshold array directly to the image samples.

    Further performance, memory use, and stability improvements with the new
    features introduced in 9.00, as well as Unix/Linux build fixes, plus the
    usual assorted bug fixes.

    For a list of open issues, or to report problems, please visit
    bugs.ghostscript.com.

    Incompatible changes

    No recorded incompatible changes.

