!PNG2SPR
========

(c) T. R. Tanner
3 Heath Close, Corsley, Wilts BA12 7NX

email ttehtann@argonet.co.uk


This program allows conversion of graphics in the new "PNG" format to Acorn
sprite files. Note that due to the Acorn sprite formats, the program converts
16 bit RGB colours to 8 bit RGB colours. Also, transparency (when implemented)
is likely to be only an on / off mask.

The PNG spec is available from http://sunsite.unc.edu/boutell/png.html. Also
refer to http://quest.jpl.nasa.gov/Info-ZIP/people/greg/png.html.

To convert a PNG file (type B60), double click the file, or drop the file onto
the program icon on the icon bar. To save the file when converted, click the
menu button over the displayed picture, and drag the sprite to where you want
to save it, or type in a path name and click OK.

Icon Bar Menu:

Info		Standard useless program info

Single Task	When ticked. the program does not release control to the wimp.
		It therefore converts faster (but you can't do anything else!).
		Off by default.

Use Scale	When ticked, the program uses the "pHYS" chunk in the file (if
		supplied) to scale the picture. NOTE: The size is not
		guaranteed - I will supply some method of configuring real
		pixel sizes in a later version. On by default.

Use Gamma	When ticked, the program uses the "gAMA" chunk in the file (if
		supplied) to apply gamma correction. On by default.

Quit		No prizes for guessing the effect of this one!

The program supports the Acorn desktop save and help protocols.

Version history

V1.0	17 Dec 95
	This version is based on release 0.85 of the PNG spec. It implements
	the basic (i.e. compulsory) chunk types, and uses the "Title" keyword
	to give the window a title.
	It does not implement the Alpha channel, it just ignores this.
	It only works under RiscOS 3.5.

V1.01	30 Dec 95
	Better set of sprites for low res modes. Sprites now match official PNG
	sprites.
	Corrected my email address in help file :-(.
	Now deals with arbitrary length chunks.
	16bpp greyscales currently produce some inspiring effects (rather than
	crashing as previously). (i.e. they come out funny colours).
	Implemented gamma correction (using file gamma only)
	Fixed bug which occured if 1st line of pic was not filter type 0 or 1
	(i.e. it referred to a non-existant previous line).

Tedious legal message
=====================

   This application is freeware. It can be distributed freely as long as only
reasonable charges are made for media and distribution. I retain copyright on
all program code and documentation contained in this distribution.

   This software is supplied ”as is•: I make no warranty, expressed or
implied, of the merchantability of this software or its ˛tness for any
particular purpose. In no circumstances shall I be liable for any damage,
loss of pro˛ts, or any indirect or consequential loss arising out of the use
of this software or inability to use this software, even if I have been
advised of the possibility of such loss.

   In other words, if your computer crashes, blows up, you lose all your work
etc. all because of !Png2Spr, don‘t blame me.

Acknowledgments

Thanks are due to:

Greg Roelofs, for being helpful

Nick Smith, ANT Ltd, for sending me the official PNG sprites and
pointing out that I can't spell my own name.