History of Ghostscript versions 9.n

## Table of contents

# History of Ghostscript versions 9.n

- Version 9.56.0 (2022-03-14)

This document is a record of changes in Ghostscript releases numbered 9.xx.

Important: see Version 9.56.0 Changelog

## Version 9.56.0 (2022-02-22)

Highlights in this release include:

- New PDF Interpreter: This is an entirely new implementation written in C (rather than PostScript, as before). For a full discussion of this change and reasons for it see: Changes Coming to the PDF Interpreter.

  In this (9.56.0) release, the new PDF interpreter is now ENABLED by default in Ghostscript, but the old PDF interpreter can be used as a fallback by specifying `-dNEWPDF=false`. We've provided this so users that encounter issues with the new interpreter can keep working while we iron out those issues, the option will not be available in the long term.

  This also allows us to offer a new executable (`gpdf`, or `gpdfwin??.exe` on Windows) which is purely for PDF input. For this release, those new binaries are not included in the "install" make targets, nor in the Windows installers.

- Calling Ghostscript via the GS API is now thread safe. The one limitation is that the X11 devices for Unix-like systems (x11, x11alpha, x11cmyk, x11cmyk2, x11cmyk4, x11cmyk8, x11gray2, x11gray4 and x11mono) cannot be made thread safe, due to their interaction with the X11 server, those devices have been modified to only allow one instance in an executable.

- The `PSD` output device now writes ICC profiles to their output files, for improved color fidelity.

- Our efforts in code hygiene and maintainability continue.

- The usual round of bug fixes, compatibility changes, and incremental improvements.

- (9.53.0) We have added the capability to build with the Tesseract OCR engine. In such a build, new devices are available (pdfocr8/pdfocr24/pdfocr32) which render the output file to an image, OCR that image, and output the image "wrapped" up as a PDF file, with the OCR generated text information included as "invisible" text (in PDF terms, text rendering mode 3).

  Mainly due to time constraints, we only support including Tesseract from source included in our release packages, and not linking to Tesseract/Leptonica shared libraries. Whether we add this capability will be largely dependent on community demand for the feature.

  See Enabling OCR for more details.

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

### Incompatible changes

#### Included below are incompatible changes from recent releases (the specific release in question is listed in parentheses). We include these, for now, as we are aware that not everyone upgrades with every release.

- (9.55.0) Changes to the `device API`. This will affect developers and maintainers of Ghostscript devices. Firstly, and most importantly, the way device-specific "procs" are specified has been rewritten to make it (we think!) clearer and less confusing. See The Interface between Ghostscript and Device Drivers and The Great Device Rework Of 2021 for more details.

- (9.55.0) The command line options `-sGraphicsICCProfile=___`, `-dGraphicsIntent=#`, `-dGraphicsBlackPt=#`, `-dGraphicsKPreserve=#` have been changed to `-sVectorICCProfile=___`, `-dVectorIntent=#`, `-dVectorBlackPt=#`, `-dVectorKPreserve=#`.

- (9.53.0) As of 9.53.0, we have (re-)introduced the patch level to the version number, this helps facilitate a revised policy on handling security-related issues.

  Note for GSView Users: The patch level addition breaks GSView 5 (it is hardcoded to check for versions `704-999`. It is possible, but not guaranteed that a GSView update might be forthcoming to resolve this.

- (9.52) `-dALLOWPSTRANSPARENCY`: The transparency compositor (and related features), whilst we are improving it, remains sensitive to being driven correctly, and incorrect use can have unexpected/undefined results. Hence, as part of improving security, we limited access to these operators, originally using the `-dSAFER` feature. As we made "SAFER" the default mode, that became unacceptable, hence the new option `-dALLOWPSTRANSPARENCY` which enables access to the operators.

- (9.50) There are a couple of subtle incompatibilities between the old and new SAFER implementations. Firstly, as mentioned in the 9.50 release notes, SAFER now leaves standard PostScript functionality unchanged (except for the file access limitations). Secondly, the interaction with `save`/`restore` operations has changed. See SAFER.

  Important Note for Windows Users:
  The file/path pattern matching is case-sensitive, even on Windows. This is a change in behaviour compared to the old code which, on Windows, was case insensitive. This is in recognition of changes in Windows behaviour, in that it now supports (although does not enforce) case sensitivity.

- (9.27) The process of "tidying" the PostScript namespace should have removed only non-standard and undocumented operators. Nevertheless, it is possible that any integrations or utilities that rely on those non-standard and undocumented operators may stop working or may change behaviour.

  If you encounter such a case, please contact us (Discord, #ghostscript IRC channel, or the gs-devel mailing list would be best), and we'll work with you to either find an alternative solution or return the previous functionality, if there is genuinely no other option.

### Changelog

From 9.55.0 onwards, in recognition of how unwieldy very large HTML files can become (History9.html had reached 8.1Mb!), we intend to only include the summary highlights (above).

For anyone wanting the full details of the changes in a release, we ask them to look at the history in our public git repository: ghostpdl-9.56.0 log.

If this change does not draw negative feedback, History?.htm file(s) will be removed from the release archives.

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Ghostscript version 9.56.1, 4 April 2022