home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
EnigmA Amiga Run 1997 June
/
EnigmA AMIGA RUN 19 (1997)(G.R. Edizioni)(IT)[!][issue 1997-06][EAR-CD III].iso
/
imagestudio
/
imagestudio68000
/
docs
/
png_io_readme.txt
< prev
next >
Wrap
Text File
|
1995-06-07
|
3KB
|
126 lines
README.txt
~~~~~~~~~~
Introduction
------------
Welcome to the ImageStudio PNG IO module. This module is
currently the working version of the PNG module and is still
not completely finished. It will not be fully complete until
the PNG library, on which it is based, reaches v1.0. The
current version is v0.6. This module should therefore be
considered as "work in progress".
How to
------
To install this module into ImageStudio 2.1.x, simply copy
either 'PNG000.isio' or 'PNG020.isio' into the ImageStudio
Modules/IO directory and restart ImageStudio. The '000'
version should be used on Amigas with a 68000 processor, the
'020' version can be used with 68020 and above.
Disclaimer
----------
The authors are not responsible for any damage done or loss of
data caused by using this module.
Copyright
---------
This package is freely distributable.
All parts of this package are Copyright 1995 Andy Dean and
Graham Dean.
The Authors
-----------
The PNG module, and ImageStudio, is written by Andy Dean and
Graham Dean.
The PNG library is written by Group42 and is available via
anonymous ftp at:
ftp.uu.net /graphics/png
Graham is available at:
14 Fielding Avenue
Poynton
Stockport
Cheshire
SK12 1YX
ENGLAND
Andy is available via Email at:
adean@eleceng.ucl.ac.uk
Documentation
-------------
This is extracted from the ImageStudio documentation:
PNG
---
Name
PNG
Load types
Colour mapped, 24, 32 and 48bits.
Save types
Colour mapped, 24bit.
Description
PNG is the license free replacement for the GIF file format.
After the controversy with the LZW compression algorithm used in
the GIF file format, it was decided that a new standard should be
created which uses the license free LZ compression algorithm along
with many improvments over the GIF file format (e.g. support for
24bit images). PNG is that format, and supports many advanced
features to obtain the best lossless compression for any type of
bitmap image. PNG also supports features that will find themselves
useful in World Wide Web browsers, etc...
A high degree of compatibility is obtained with our PNG
loader/saver, as it is based in part on the PNGlib code by Group42.
ARexx OPEN command ARGS
None.
ARexx SAVE command ARGS
INTERLACE,TRANSPARENCY/S,TRANSPCOLOUR/N
INTERLACE
By default PNG files are not interlaced, however by
specifying an INTERLACE value of ADAM7 they can be saved out
with 7 levels of interlacing. This gives progressive redraw
for World Wide Web browsers.
Note: This interlace has nothing to do with the Amiga's
interlaced screens.
TRANSPARENCY/S
By specifying this switch, one colour out of the image's
pallete can be made `transparent', causing the background
colour to show through. This again can be useful with World
Wide Web browsers. By default, the transparent colour is
colour 0, but this can be changed (see below).
TRANSPCOLOUR/N
This is the palette entry number that is made transparent if
the TRANSPARENT switch is used.
Example
The following saves out a standard PNG format file:
SAVE FILE "Image.png" FORMAT "PNG"
The following saves out a PNG file with interlace:
SAVE FILE "Image.png" FORMAT "PNG" ARGS "INTERLACE=ADAM7"
The following saves out a PNG file with a transparent colour of 10:
SAVE FILE "Image.png" FORMAT "PNG",
ARGS "TRANSPARENCY TRANSPCOLOUR 10"