                              View ST/TT v1.32
                              ----------------

Copyright 1992 by Copson of Unit Seventeen, Sweden. All rights reserved.

The programs may only be copied unaltered with this text attached to it.


MANIFEST
--------
The archive should contain following files:

VIEW_TT.PRG   -  The Viewer for a MC68030-based computer (TT)
VIEW_ST.PRG   -  The Viewer for a MC68000-based computer (ST/STe)
VIEWTTST.TXT  -  This text


DESCRIPTION
-----------
With this program you can show pictures in various formats in either ST-Low,
ST-Medium, ST-High, TT-Low or TT-Medium on the Atari TT030 and ST-Low on
the Atari ST and STe. It can also use the current VDI-resolution and might
even work together with screen enhancements such as overscan or screen
doublers.

The formats supported so far is:

TGA         Truevision Targa. 16, 24 and 32-bit true color pictures.
RAW         Output format from the QRT raytracer. 24-bit true color.
IMG         Output format from the Vivid raytracer on the PC, not to
            be confused with the GEM-Image-Format. 24-bit true color.
IFF HAM     IFF Hold And Modify from Commodore Amiga. Max 4096 colors.
IFF ILBM    IFF Interleaved bitmap. Max 256 colors.
GIF87a      Graphics Intechange Format by CompuServe. Max 256 colors.
SPC, SPU    Spectrum 512 pictures compressed and uncompressed.
PI?, PC?    Degas and Degas Elite pictures, compressed and uncompressed.
NEO         Neochrome low resolution.
ART         Art Director low resolution.
DOO         Doodle high resolution.
IMG         GEM-Image format, 1 bitplane.

The special thing with this program compared to others, is its ability to
view the pictures quick and easy in different screen resolutions, without
having to restart the program and change resolution manually. The program
is of course coded in assembly language to make it as fast as possible.

All pictures are expanded to its true colors and are then reduced to the
number of colors of the resolution which it is to be shown in. For example,
if a TGA-picture with 16M colors are to be shown in TT-Low, it first loads
the picture in the memory and then reduces it to 256 unique colors. This
method consumes lots of memory, so don't expect to show extremely big
pictures if you aren't equipped with extremely much memory...
No kind of dithering is currently used for either resolution, so don't expect
too much from true color pictures on the ST/STe...

IFF-pictures (ILBM) from the PC often contains a so called Tiny-picture, which
is a reduction of the original picture which are shown in the fileselctor in
Deluxe Paint for the PC. This program can also display the Tiny-picture and
textchunks contained in the picture.

View TT is optimized especially for the 68030 and should run on the Atari
TT030 as well as an ST equipped with a 030-board.

View ST runs both on the ST and TT.

HOW TO USE THE PROGRAM
----------------------
The program can either be started with a commandline which contains the file
to be showed, or without any arguments. In the later case a fileselector
appears in which you choose your picture from.

The program loads the picture and unpacks it to memory. You choose which
resolution you want to see it in, from the main alert. Your choices are:

ST: This button shows an alert with the three ST-resolutions, ST-Low,
    ST-Medium and ST-High. If you choose an illegal button, the program
    shows a error message.

TT: This button shows an alert with the two TT-resolutions for color:
    TT-Low and TT-Medium. The third button is named Current and shows the
    picture in the current resolution. This is useful if you run in a non-
    standard resolution such as interlace. The programs then tries to read
    the screen parameters from the VDI and use these.

When you have choose your resolution, the program displays the picture.
You can now use the keys to expand or move the picture. When you press Undo
you are returned to the resolution alert, and you can choose to show the
picture in a different resolution or to load a new one.

You quit the program by choosing Cancel in the fileselector.


KEYBOARD COMMANDS
-----------------

Arrows      If the picture is larger than the screen, you can use the arrows to
            scroll around in the picture. If it is smaller than the screen, the
            arrows are used to move around the picture on the screen. The
            movement is exponential, the longer you press down the key, the
            faster is the movement.

S           Save picture in Degas or Degas Extended format, see description
            below. You are confronted with a fileselector in which you choose
            filename for the picture to be saved.

R           Save picture in QRT's RAW-format. Mainly to be used with the
            Photochrome program to view pictures with many colors on an ST or
            STe. This function is only availible in ST-Low. The program always
            saves what is shown on the screen to a file. It is therefore
            possible to zoom or reduce the picture so it fits the screen
            before saving it.

T           If an IFF-picture contains a reduced image, a TINY, this could
            be viewed with this key. IFF-pictures which are drawn with Deluxe
            Paint on the PC can contain such images.

C           Center picture. If the picture is smaller than the screen, this
            aligns the picture in the middle of the screen. If the picture is
            bigger, no action is taken.

I           Zoom in picture at y-axis. Exponential increase.

O           Zoom out picture at y-axis. Exponential increase.

X           Zooms the picture in x-axis in four steps: (Previous D-key)
            100%, 50%, 25% and 12,5%
Y           Zooms the picture in y-axis in four precalculated steps:
            200%, 100%, 50% and 25%.

Undo        Return to the main alert.

Help        Shows a alertbox with descriptions of the key commands.


EXTENDED DEGAS FORMAT
---------------------
For saving the pictures, I have extended the standard Degas-format PI0 to
the TT-resolutions. Following is a description of the format I use:

               ST-Low                  TT-Low                  TT-Medium

Extension      PI0                     PI4                     PI5
Resolution     1 word: $0000           1 word: $0007           1 word: $0004
Colormap       16 word                 256 word                16 word
Bitmap         32000 bytes             153600 bytes            153600 bytes
Total length   32034 bytes             154114 bytes            153634 bytes

DISCLAIMER
----------
I don't have any responsibilities for any typ of damage caused by using
this program.

This program is Freeware, which means that it is free for everyone to use
without having to pay anything. It is free to be copied only if no changes
are made to the archive itself or the files in the archive. I claim to have
copyright on the code, so if you rip anything, you could at least mention
me as the original author...

If you find the program useful and would like further development, by
supporting more formats or future screenresolutions (e.g. F030-rez),
send me your comments on a nice postcard. If I don't get any responce to
the program, it is not likely to continue to grow... Future enhancements
planned are RSC-interface, more formats, more resolutions, but that depends
on YOU!

Have fun with the program!

PLEASE SUPPORT SHAREWARE AUTHORS!


SOURCES
-------
ST Picture Formats edited by David M. Bagget
Spectrum 512-viewer from ST Magazin by Enno Borgsteede
GIF(tm)-unpacking routine in assembler by Lars Brinkhoff
JPEG-sources for the PC
GIF(tm) Specification
and of course the ATARI ST Profibuch by Sybex Verlag, GmbH

Thanks to my betatesters Elof, Jason and Knightman of Unit Seventeen,
Roine Stenberg and Niklas Nylin.

GIF is a trademark of CompuServe, Incorporated.


ADDRESSES OF THE AUTHOR
-----------------------

Fido Netmail:
Conny Pettersson, 2:204/419.5

Email (FidoNet Gateway):
Conny_Pettersson@p5.f419.n204.z2.fidonet.cd.chalmers.se

By Letter:
Conny Pettersson
Hovetorpsgatan 66
S-582 64  LINKOEPING
SWEDEN
