!PNG2SPR 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).

v1.10	11 Sept 96
	Rewritten in C using the PNG & ZLib reference libraries, and the Acorn
	Toolbox.
	Supports multiple images, all with individual %age hourglasses.
	16bpp greyscales now work.
	"Iconise" with standard pinboard works properly.
	Works under RISCOS pre 3.5 (I hope).

v1.11	21 Sept 96
	Fixed bug to do with memory not being zeroised, causing corrupt sprite
	names & psychedelic pallettes on Risc PCs.
	Added a small info window that says it hasn't been written yet.

v.12	22 Sept 96
	Corrupting interlaced files when < 8 bits per character. Oogh.
	32 bpp files not working with !Paint on StrongArm - new version doesn't
	like a right hand bit > 31 (!).
	Added transparency configuration.

v1.13	29 Dec 96
	Corrected tRNS handling for greyscale images. Added a configuration
	option for greyscale backgrounds. 16 & 8 bit greyscales with masks get
	transformed to RGB pics, as it's currently the only sensible way I can
	deal with them.

v1.14	25 Jan 97
	Running with LibPng 0.90

v1.20	1 Mar 97
	First version to convert sprite files to PNG files. Just drop a sprite
	onto the iconbar icon & drag the save box to where you will.

v1.21	28th July 97
	Deals more cleanly with mega large images. calloc() falls over if you
	give it an excessive "size" argument :-(.
	Running with LibPng 0.96.
	16 & 8 bit greyscales with transparency chunks and masks now work
	properly, and remain the correct colour type!
	Fixed obscure bug with gamma corrections on gray scale images.
	Fixed bug in handling pHYs aspect ratios.

v1.22	21st September 1997
	Improved memory handling for strings & things.
	Fixed memory leak on writing due to bug in libpng.
	Deal with masks when converting sprites to PNG files for all but 8pp
	images.
	Get correct palette for images using Wimp palette.
	Fixed bug when creating 32bpp masks. Clears supremacy bits on 32bpp
	pictures.

v1.23	9th November 1997
	Uses Virtual Memory if Virtualise loaded.
	Chronic bug decoding masks for 32bpp pictures.
	Fixed some bugs dealing with decoding backgrounds - bug in libpng.
	File system errors no longer fatal - note that this may cause problems
	if you close a file which is being decoded...

v1.24	31st December 1997
	Added some code to skip sprite headers if supplied.
	Deal with real (pre RiscOS 3.5) 64 entry 256 colour sprites (what an
	awful hack!).

v1.25	25th May 1998
	This was only really to add some line number information to error
	reports.
	Set "Alias" and "UnAlias" aliases for pre-riscos 3.5 users

v1.26	18th June 1998
	This should now display PNG files (<=256 colours) OK on RiscOs 3.1.
	Thanks to Dr AJ Lindop for that one...

v1.30	2nd Sept 1999
	Rebuilt with PNG library v1.0.3c. Some minor interface improvements.

v1.31	18th Sept 1999
	And latest zlib library for better compression. Will now mask 256
	colour sprites if not all palette colours are different. Fixed a small
	memory leak.

v1.32	29th March 2000
	Fix problem with default palettes for sprites. NOTE: For 2, 4 and 16
	colour sprites, this selects DEFAULT wimp colours.
	Added "batch processing" command line type interface.

v1.33	18th August 2001.
	Rebuilt with PNG library v1.0.6.
	Prescan of 256 colour masked sprites to see which colours are actually
	used. This means more masked sprites work properly.

	TO DO:
	Discard masked colours
	Warning if mask not saved
	Option to optimise sprite pallettes before processing
	Option to use current wimp or default colours