
                       alvi - Alkor JPEG-Viewer

                             Users Manual

                           Version: 0.05beta
                           11. September 1996

                   Copyright (c) 1996 by Uwe Haase.

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          Die deutsche Version dieses Textes heisst README.TXT
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 Contents
==========


1.   General
1.1.   Copyright
1.2.   Liability
1.3.   Thanks
1.4.   Registration
1.5.   Bug reports
1.6.   Updates

2.   Installation
2.1.   Starting alvi

3.   How alvi works
3.1.   Background
3.2.   How to use alvi
3.2.1.   Info
3.2.2.   Load
3.2.3.   Options
3.2.4.   Setup

4.   FAQ


 1. General
============


 1.1. Copyright
================

alvi is not to be copied and/or sold for money.  This specifically (but not
exclusively) includes distribution on CD-ROM or floppies for any kind of a
fee. Free distribution without any fees is allowable.

alvi darf nicht gegen Entgeld vervielfaeltigt und/oder verkauft werden. Dies
schliesst ausdruecklich den Vertrieb auf CD-ROM oder Disketten gegen Entgeld
aus. Unentgeltliche Weitergabe ist statthaft.


 1.2. Liability
================

alvi is in a very early state of development.
Use alvi at your own risk. alvi comes without any warranty.
In no event shall I be liable for any damages whatsoever arising out
of the use of or inability to use of alvi.


 1.3. Thanks
=============

alvi uses the

- JPEG library from the Independent JPEG Group (IDG)
  (Release 5, 24-Sep-94)

and the

- XGEM2 library (08-Sep-96) from Matthias Hentschel
  (http://rcs.urz.tu-dresden.de/~mhentsch).

I would not have been able to complete alvi so quickly without these two
libs.

 1.4. Registration
===================


 Why is alvi free of charge?
----------------------------

I wrote alvi for myself. Some people have asked me to publish alvi. If I
were to demand money for it, somebody might think it reasonable to expect
more achievements (such as bug fixing or updates).
If I make it free, then it's my very own decision, whether I choose to
find time to work on alvi, or not.


 Why should you nevertheless register?
--------------------------------------

I'm interested to know who and how many people uses alvi.


 How do you register?
---------------------

The registration is free of charge.
Just send me a postcard. (A nice view of your hometown or a beautiful
landscape should be the motive). 

Here is my adress:

   Uwe Haase
   Wiesenstr. 29
   D-01277 Dresden
   GERMANY


 What do you get from registering?
----------------------------------

I will inform you via eMail, if new versions of alvi are released. Registered
users also have a bigger influence on new functions.


 1.5. Bug reports
==================

Send your bug report to haase@alkor.sax.de


 1.6. Updates
==============

The release of new versions depends on two conditions:

- I need find spare time to work on alvi.
- I receive some response from the users.

There will be no updates, if neither of these conditions is met.
You can at least influence the 2nd condition.

Updates will be announced to all registered users.

All published versions are available from my homepage:

   http://www.sax.de/~haase/atari.html


 2. Installation
=================

Extract the archive.
You get a new folder named ALVI<version>, like ALVI005B.


 2.1. Starting alvi
====================

You have 3 choices to view JPEGs with alvi:

- Start ALVI.APP.
  Press the "Laden" button (Load); select a JPEG file to load.

- Drop ALVI.APP on the ATARI desktop (TOS version 2.05 and newer).
  Drag JPEG files onto the icon.

- Install alvi as the application for JPEG files.
  (Choose "Install Application" from the Options menu)
  Doubleclick a JPEG file.


 3. How alvi works
===================


 3.1. Background
=================

 What is alvi?
--------------

alvi is the short form of Alkor JPEG-Viewer.
And that's the task of alvi, to show JPEGs.


 Why another viewer?
--------------------

Most JPEG viewers need more RAM than necessary. They are often not
optimised for speed. (There are special versions that use the DSP of the
FALCON, but these programs are not usable on a plain ST.)
I know of no viewer that is able to view many large JPEGs quickly in GEM
windows.


 Limits
--------

Only JPEG format is supported at the moment.
(Other formats might possibly be supported in the far future.)

The display of the current version is only monochrome.
The program can be run in 4/16/256/... colors too, but the display will
still be monochrome.

Actual dithering method is Floyd Steinberg Dithering.

alvi can handle nearly any size of JPEG file.
If alvi runs out of memory, you have to increase the shrinking factor.
(See section 3.2.3)

Required RAM:

   192 KB (maximum) needed for the program, including buffers, plus the
   RAM requirement of the displayed pictures. Use this formula:

   picture size x * y / shrinking factor ^2 / 8 byte of RAM for each picture.

                       (shrinking factor: 1, 2, 4 or 8)

   For example: Original size 1280 * 1024, shrinking factor 8.

                1280 * 1024 / 64 / 8 = 2560 byte

Note:  The loading time is decreased by higher shrinking factors!


 3.2. How to use alvi
======================


There are four buttons in the main window of alvi:

  Info / Laden / Optionen / Setup
 (Info / Load  / Options  / Setup)

Let me explain the functions of these buttons:


 3.2.1. Info
=============

This shows a short informational message about the program, including
the version number and date/time of compilation.


 3.2.2. Load
=============

Just choose a JPEG file to load!


 3.2.3. Options
================

There is only one option at the moment.


 Bildgre (Picture size)
-------------------------

You can choose a shrinking factor of Originalgre (original size)
2, 4, or 8. Factor 8 shrinks a 640 x 480 pixel picture to
80 x 60 pixels.

You have to adjust the shrinking factor before loading the picture!
Default value is shrinking factor 2.


 3.2.4. Setup
==============

No setup available at the moment.


 4. FAQ
========

Q01: How can I exit alvi?

     Press the close button of the main alvi window!
