This is a collection of sample images which have been processed
for display on four or eight bit-per-pixel Xarm displays.  The
images use the standard static colour maps from these displays.
Processing involved taking a 24 bit-per-pixel master from a
colour scanner and using a combination of gamma correction,
mapping to the colour map and error propagation to produce visually
acceptable results.  Only one sample image for 4 bit-per-pixel
display is included; obviously images processed for 4 bit-per-pixel
are noticeably lower quality than the 8 bit-per-pixel ones, however
the results can be surprisingly good considering that only 16
colours are used.

The images are stored as GIF files and may be displayed using the
xloadimage program and a suitable display - do not expect sensible
results if the 8 bit-per-pixel images are displayed on a 4 bit-per-pixel
screen or vice versa.

Further processing of the images is not possible; although the
images may look visually acceptable much of the information in the
original has been lost.  Further processing will enhance the
tricks used to produce a visually acceptable result as much as
the original image.

"Gamma correction" has been used to distort the intensity range in
the images.  The net result is that the intensities in the image
are compressed at the bright end of the range and expanded at the
dark end.  This helps offset the highly compressed range of
intensities available in the Xarm server (the range is only 15:1).
When this is not done the dark regions of the image tend to lose
detail.

Error propagation allows a wider range of colours to be represented
at the cost of obscuring detail in the image.  Use the xmag program
to examine how colours are simulated in an area of an image which
is of relatively constant colour.  The effect is far more noticeable
in the 4 bit-per-pixel image.

COPYRIGHT
---------

All of these images are copyright; they are used with the permission
of the copyright holder.  As with the other parts of RISC iX this
allows you to use them on RISC iX systems, but not to give them away
to people who do not hold a RISC iX license.

IMAGES
------

All the images are in GIF format.  The only 4 bit-per-pixel image
supplied is:

GreatShepherd.g4:	800x600
	The top of Glencoe Pass.  Taken from Buachaille Etive Beag
	towards Stob Dearg on Buachaille Etive Mor.  See the
	description of GreatShepherd.g8 below (this image is
	cropped slightly differently because of the different
	screen size).  The image is intended for use as a background
	(use xsetbg(1)) on a Super VGA display.
	Copyright (C) 1987 Ann Copestake.

The remaining images are 8 bit-per-pixel images intended for use
on the corresponding VGA display.  This display can also be used
with Super VGA monitors.  The default X system configuration makes
all VGA screens 8 bits deep.  On a Super VGA display screens 0 and
1 are 800x400x4 bits-per-pixel, screen 2 is 640x480x8 bits-per-pixel.
Use xswitcher(1) to switch between the screens.

A440.g8:		130x208
	The Archimedes A440 computer.  Copyright (C) Acorn Computers Ltd.

A540.g8:		130x191
	The Archimedes A540 computer.  Copyright (C) Acorn Computers Ltd.

Arncliffe.g8:		392x256
	Arncliffe in the North York Moors.
	Copyright (C) 1990 Pete & D Copestake.

Butterfly.g8:		220x265
	A tortoiseshell butterfly.
	Copyright (C) 1990 Pete & D Copestake.

GreatShepherd.g8:	640x480
	This image is intended for use as a root background, using
	xsetbg (see xloadimage(1)).
	The top of Glencoe Pass.  Taken from Buachaille Etive Beag
	towards Stob Dearg on Buachaille Etive Mor.  The water
	in the top left is the Blackwater Reservoir.  Taken on
	Monday August 3rd 1987.
	Copyright (C) 1987 Ann Copestake.

Lane.g8:		256x392
	Somewhere in the North York Moors near Robin Hood's Bay;
	a sunken lane.
	Copyright (C) 1990 Pete & D Copestake.

NorthYorkMoors.g8:	392x256
	Near Fylingthorpe in the North York Moors.
	Copyright (C) 1990 Pete & D Copestake.

Pisa.g8:		205x370
	Pisa (the leaning tower thereof).
	Copyright (C) 1988 John Bowler.

PostBox.g8:		183x300
	The post box outside King's College Cambridge.
	Copyright (C) 1989 Ann Copestake.

R260.g8:		130x208
	The Acorn R260 workstation.
	Copyright (C) 1990 Acorn Computers Ltd.

R260A540.g8:		124x208
	The Acorn R260 workstation and the Acorn Archimedes A540.
	Copyright (C) 1990 Acorn Computers Ltd.

RobinHoodsBay2.g8:	392x256
	From the shore below Robin Hood's Bay in Yorkshire looking
	towards the old village.
	Copyright (C) 1990 Pete & D Copestake.

RobinHoodsBay3.g8:	640x480
	Boats on the shore below Robin Hoods Bay - intended for use
	as a root background using xsetbg.
	Copyright (C) 1990 D Copestake.

Wood.g8:		350x217
	A picture of work on a roof truss.
	Copyright (C) Acorn Computers Ltd.
