JPEG.svobject

  © 1994 by Andreas R. Kleinert.

  FREEWARE. All rights reserved.
  This software is based in part on the work of the Independent JPEG Group.

  Version      : 2.3
  Release Date : 08.06.1994


  Requirements
  ~~~~~~~~~~~~
  - OS V2.04+ (V37)+ and its libraries
  - 68020+, optimized for 68030
  - superviewsupport.library V1+


  Description
  ~~~~~~~~~~~
  JPEG.svobject is an external Library-Module for the superview.library V2+.

  It contains SVDriver-Support for the superview.library V3+, and
  needs any SVDriver with ChunkyPixel-Support.

  It supports reading and writing of JPEG Files as they are written by
  "The Independent JPEG Group's JPEG Software" (release 4).

  In detail these are :

  Reading :

   - JPEG (IJG-JFIF), with output in 256 Colors or 24 Bit

  Writing :

   - JPEG (IJG-JFIF), from upto 8 or 24 Bit Input


  Remarks
  ~~~~~~~
  * JPEGTMP:
  * Temporary data will be written to a directory assigned to "JPEGTMP:",
    if neccessary, but please note, that this might affect your HardDisk,
    if this program crashes (e.g. on a corrupt JPEG-picture) !
    So don't blame me, if this happens, but select a _safe_ place for this
    temporary-file directory !

  * Functionality :
  * OK, let's get to the more positive things :
    Since the small problems in the first beta version, some bugs in using
    the IJG-Sources have been fixed, and so almost any JPEG (".JPG") pictures
    out there should be read and displayed correctly.

  * Writing JPEG-Files :
  * Note, that JPEG-compression is lossy, which means that the original
    picture cannot be reconstructed totally.
    Only JPEG-compress files, from which you have backups, or files which
    you never want to edit and enhance again.
    You should always control the results from saving an JPEG-File : in
    some special cases (e.g. many thin lines on the screen) there may
    occur strong differences to the original picture.


  ControlPad-Switches
  ~~~~~~~~~~~~~~~~~~~
  ControlPad-Name     : "ENV:superview-library/JPEG.controlpad"
  ControlPad-Commands : - COLORDEPTH = <8/24>
			  ; shell the output be 8 or 24 Bit Data ?
			  ; default is 8 Bit data


  Limitations
  ~~~~~~~~~~~
  Please note, that the De/Encoding Routines of the Library are not (yet)
  fully re-entrant, so that only one Task may De/Encode a picture at a time.
  The Library itself manages it, that the other Task has to Delay() until
  the De/Encoding Routines are "free" again.
  This makes NOT REALLY A MATTER, because De/Encoding takes so much of the
  processor's time, that it is NOT EFFICIENT to EN/DECODE TWO OR MORE
  pictures AT THE SAME TIME ANYWAY !
  Nevertheless parallel Decoding while Encoding should be possible without
  problems (if it does not work, please report it to me !).


  Author
  ~~~~~~
  Andreas R. Kleinert
  Grube Hohe Grethe 23
  D-57074 Siegen
  Germany


  History
  ~~~~~~~
  V2.3 (08.06.1994) :

   - now also writes JPEG-Files.
     Input  : - BIT/ONEPLANE upto 8 Bit
	      - ONEPLANE with 24 Bit
     Output : 24 Bit JPEG
   - Note : if you do not need writing of JPEG-Files, you may still use
	    the previous versions. They have almost the same functionality,
	    but because they are "read-only", they're much shorter ...


  V2.2 (06.06.1994) :

   - removed superviewsupport.library from package, use the version
     supplied with superview.library V6+ instead !


  V2.1 (21.05.1994) :

   - beta-version(s) : V2.0 (nearly all major bugs fixed now)
   - first "public release" version


  Literature
  ~~~~~~~~~~
  [1] The Independent JPEG Group's software package with Source-Code(s)
      and Documentation.
      (See statement at the top of this Doc-File !)

  Credits
  ~~~~~~~
  This software is based in part on the work of the Independent JPEG Group.
  Release 4 of 10-Dec-92 was used (as found on the Walnut Creek "Source
  Code CDROM", March 1994, Directory "MSDOS/GRAPHICS", File "JPEGSRC4.ZIP").


  Copyrights
  ~~~~~~~~~~
  Some of the mentioned names or products above may be copyrighted by
  companies or trademarks of companies.