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diff --git a/kernel/kls_jbig/libjbig/ANNOUNCE b/kernel/kls_jbig/libjbig/ANNOUNCE new file mode 100644 index 0000000..35baa23 --- /dev/null +++ b/kernel/kls_jbig/libjbig/ANNOUNCE @@ -0,0 +1,147 @@ + +JBIG-KIT lossless image compression library +------------------------------------------- + +by Markus Kuhn + + +The latest release of JBIG-KIT can be downloaded from + + http://www.cl.cam.ac.uk/~mgk25/jbigkit/ + +JBIG-KIT implements a highly effective data compression algorithm for +bi-level high-resolution images such as fax pages or scanned +documents. + +JBIG-KIT provides a portable library of compression and decompression +functions with a documented interface. You can very easily include +into your image or document processing software. In addition, JBIG-KIT +provides ready-to-use compression and decompression programs with a +simple command line interface (similar to the converters found in Jef +Poskanzer's PBM graphics file conversion package). + +JBIG-KIT implements the specification + + International Standard ISO/IEC 11544:1993 and ITU-T Recommendation + T.82(1993), "Information technology - Coded representation of picture + and audio information - progressive bi-level image compression", + <http://www.itu.int/rec/recommendation.asp?type=folders&parent=T-REC-T.82>, + +which is commonly referred to as the "JBIG1 standard". JBIG (Joint +Bi-level Image experts Group) is the committee which developed this +international standard for the lossless compression of images using +arithmetic coding. Like the well-known compression algorithms JPEG and +MPEG, JBIG has also been developed and published by the International +Organization for Standardization (ISO) and the International +Telecommunication Union (ITU). See also + + http://www.jbig.org/jbighomepage.html + http://www.iso.ch/ + http://www.itu.int/ + +The JBIG compression algorithm offers the following features: + + - Close to state-of-the-art lossless compression ratio for high + resolution bi-level images. + + - About 1.1 to 1.5 times better compression ratio on typical + scanned documents compared to G4 fax compression (ITU-T T.6), + which has been the best compression algorithm for scanned + documents available prior to JBIG. + + - Up to 30 times better compression of scanned images with dithered + images compared to G4 fax compression. + + - About 2 times better compression on typical 300 dpi documents + compared to 'gzip -9' on raw bitmaps. + + - About 3-4 times better compression than GIF on typical 300 dpi + documents. + + - Even much better competitive compression results on computer + generated images which are free of scanning distortions. + + - JBIG supports hierarchical "progressive" encoding, that means it is + possible to encode a low resolution image first, followed by + resolution enhancement data. This allows, for instance, a document + browser to display already a good 75 dpi low resolution version of + an image, while the data necessary to reconstruct the full 300 dpi + version for laser printer reproduction is still arriving (say + over a slow network link or mass storage medium). + + - The various resolution layers of a JBIG image in progressive + encoding mode together require not much more space than a + normal non-progressive mode encoded image (which JBIG also + supports). + + - The progressive encoding mode utilizes a quite sophisticated + resolution reduction algorithm which offers high quality low + resolution versions that preserve the shape of characters as well + as the integrity of thin lines and dithered images. + + - JBIG supports multiple bit planes and can this way also be used + for grayscale and color images, although the main field of + application is compression of bi-level images, i.e. images with + only two different pixel values. For grayscale images with up to + 6 bit per pixel, JBIG performs superior to JPEG's lossless + mode. + +JBIG-KIT is free software under the GNU General Public License. Other +license arrangements suitable for commercial applications are +available as well, please contact the author for details. JBIG-KIT +provides a portable library implemented in ANSI/ISO C for encoding and +decoding JBIG data streams, along with documentation. The library is +not intended for 8-bit or 16-bit machine architectures (e.g., old +MS-DOS C compilers) on which a number of very efficient optimization +techniques used in this software are not possible. For maximum +performance, a 32-bit processor is required (64-bit systems work too, +of course). On architectures with 16-bit pointer arithmetic, only very +small images can be processed. + +Special features of the JBIG-KIT implementation are: + + - Fully reentrant multithread-capable design (no global or static + variables, isolated malloc()/free() calls, etc.). + + - Capable of handling incomplete and growing JBIG data streams in + order to allow earliest display of low resolution versions. + + - Capable of handling several incoming data streams simultaneously + in one single process and thread. + + - Especially designed with applications in mind that want to display + incoming data as early as possible (e.g., similar to the way in + which Netscape Navigator handles incoming GIF images). + + - Implements all JBIG features and options including progressive and + sequential encoding, multiple bit planes, user specified + resolution reduction and deterministic prediction tables, adaptive + template changes for optimal performance on half-tone images, + deterministic prediction, typical prediction in lowest and + differential layers, various stripe orderings, etc. Only the SEQ + and HITOLO options are currently not supported by the decoder + (they are normally never required, but could be added later in + case of user requirements). + + - Suitable for fax applications, satisfies ITU-T T.85 profile + + - Efficient code, optimized utilization of 32-bit processor + registers. + + - Very easy to use documented C library interface. + + - Included Gray code conversion routines for efficient encoding + of grayscale images. + + - Ready-to-use pbmtojbg and jbgtopbm converters. + +I will try to provide free support and maintenance for this software +for the foreseeable future, depending on my available time. + +Happy compressing ... + +Markus Kuhn + +-- +Markus Kuhn, Computer Laboratory, University of Cambridge +http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain |