Amiga Computing - Commodore Is Awesome

• REVIEW •
Bits? Planes?
T Amiga generates colour
graphics H is to overlay several "sheets"
of E memory. Each of these sheets is
called n a bit plane and together they
control o the colour of each pixel on the
screen. r
mFor
example, if a screen had a
single a bitplane it could only display
two l colours. If it had two bitplanes, it
could have four different colours.
w
a
(Check your binary arithmetic if this
doesn't make sense to you.)
y
The maximum number of bitplanes
i
the Amiga can control in this way is
n
five: Therefore it can display up to 32
wdifferent
colours.
h However. It is possible to cheat. By
iusing
a sixth bitplane and switching
cthe
display hardware into a special
h
t
h
e
The Art Department
A (TAD) makes a wonderful
Lcompanion
to the scanner, it is also a
Tpiece
of software which any graphics
Hartist
will find useful. Thankfully, it's
Oalso
an entire order of magnitude
Ucheaper,
although you'll have needed
Gto
have spent some money of memory
H expansion: You need more than 1Mb.
T TAD is an image processing suite
which works with an internal
h
e
resolution of 24 bit planes. In some
A
respects it is similar to the program
PixMate, but a little more professional
r
and a little less on the gimmicky side.
t
Back to the DIY magazine scenario.
D
and I would use TAD to provide fine
e
tuning over the contrast, brightness
p(gamma
actually) and colour balance
aof
my pictures. And separating of
rcourse,
into 24 bit cyan, yellow,
tmagenta
and black files.
m I would happily acknowledge and
emake
use of the UCR (under colour
nremoval)
and GCR (grey component
treplacement)
functions.
As a graphics artist — which I'm not,
unfortunately — I would use TAD to
convert images between the various
Amiga screen formats (from line
drawing to extra halfbrite to HAM to
32 colours to A-HAM and so forth).
I'd also use the RIP (remove
84 AMIGA COMPUTING IVovnizther
)••
"Hold And Modify" mode, the Amiga
can display all 4,096 of its possible
colours on-screen at once. It works by
using the fifth and sixth bitplanes to
control how the first four planes
control the individual red, green and
blue components individually.
This explains why HAM image
cannot deal with edges very well:
Where the colour changes suddenly
from light to dark, it takes several
pixels for all the HAM values to
follow suit.
There are several cunning ways to
improve the edge blurring — for
example, using 16 different starting
colours which can be substituted at
any time — but most put quite a strain
on the poor old Amiga and leave no
time for a program to run as well.
REPORT CARD
Sharp DE-1000 Handy Colour Scanner
and ASDG Scan lab 100 software
E695
Silica Systems 081
-
308 0 8 8 8 11111
EASE OF USE....
Within 15 minutes of delivery I had
produced some of the best Amiga
graphics I had ever seen.
11111P
VALUE
It's expensive. You can buy cars and
things for this kind of money! No if
you were buying on behalf of a
company then it's a totally different
matter. Have you seen the price of
some Mac peripherals?
TI
RESULTS
Can't fault it. Well. OK Icon. I would
like the resolution to be a bit higher.
Even 300 dpi would keep me quiet for a
bit longer.
OVERALL 9 0 %
This is an amazing device which pmves
that the Amiga is capable of doing
anything that an Apple can, only cheaper.