Alexander 
! Supervisor 
! Image Proc. 
j Utilities 
I Help 
: Exit 
Image Processing 
Figure 3: Example of a pop-ujo menu. 
Default image 
> 
Display 
> 
Pre-Processing 
* 
Feature Extraction 
» 
.Calculator 
» 
Filter 
* 
Classification 
i 
> 
The Alexander package uses the following 
minimum hardware configuration: 
Network version: 
□ Network station (e.g. Archimedes 
410) 
□ 60 Mbyte hard disk 
□ A3000 workstations with 1 Mbyte 
RAM 
Single workstation version: 
3 Archimedes 410 with 1 Mbyte RAM 
□ 20 Mbyte hard disk 
Peripherals: 
3 Philips CM 8833 medium resolution 
colour monitor 
□ Star LC10 colour dot matrix printer 
(optional) 
with the programs and data files. Once they 
have been loaded into memory, processing 
can be done within each workstation. This 
ensures that many students can be taught in 
one classroom while each student or small 
group of students can work independently 
with one workstation at desired pace. 
Alexander is wntten entirely within this window 
environment. Due to the spectral nature of 
satellite images, the only exception is that 
drag operations of data files are not suppor 
ted. However, should there be a strong 
demand for that, it could be implemented 
without much change. The output of Alexan 
der is compatible with two standard packages 
which come with the Archimedes. PAINT is a 
pixel editing program for ‘sprites' and DRAW 
is a drawing package, which can also handle 
sprites and text. (A sprite is a system-defined 
raster image with colour palette. Operations 
on sprites can be done via software interrupts 
and are thus extremely fast). DRAW is the 
most powerful of the two. Suppose the user 
has made a classification of an image. He can 
load the output sprite into DRAW and do 
some textual annotations or drawing on the 
sprite for subsequent output on a laser, ink-jet 
or dot matrix printer. 
Upgrade options: 
3 Multisync high resolution colour 
monitor 
3 2 Mbyte of RAM (A300) 
3 4 Mbyte of RAM (Archimedes 410) 
A Watford video digitizer interface can be 
plugged into the Archimedes. It allows aerial 
photographs, maps or other sources of graph 
ic information to be quickly digitized via a 
video camera and incorporated in the data 
base. 
Figure 4: Example of WIMP icons; 
a) radio-button type icons, 
b) sprite icon, 
c) menu icons, 
d) writable icon with caret.