#Amiga can't do biz
9 messages in this thread
No – the university of Lowel board is only a crippled 256 colors, just like the
Mac II with it's original color capability.
There is *rumored* to be a 21 bit (7*7*7) board in the works at CBM – I hope
that is so, because that 256 color thing is nothing but a makeshift. Who wants
to go to 256 after having 4096? Sheesh.
–Ben-
Ben;
I too love the 4096 color mode, but it has some severe resolution limits.
In addition, it's no help at all for gray scale, which is where the 256 colo4r
boards shine, since they do 256 gray scale, and we can only do 16.
i fervently hope that CBM does not abondon its lead in graphics processing for
the desk top market. There is definitely a place for 256 color capability.
I'd like to see them give us that, plus go the competition one better.
Ray
Ray, any current amiga can do 32 level gray scale. Or had you forgetten?
I know about the resolution limits – they bite me all the time.
However, it's interesting to note that the resolution limits of a HAM screen
are in most cases FAR less sever than the limits of a composite NTSC color
signal.
–Ben-
Actually, you can only do a true 16 greyscale, not a 32 greyscale. (Although
one can get intermidiary *almost* grey colors to generate a pseudo 32
greyscale.) Extra Halfbrite does not count, since not only do some of the
greys overlap when the initial registers are set for 16 grey levels, but also
because it doesn't really half the colors, rather, it shifts the color bits
once to the right, chopping off the low bit, for the extra range. So you really
don't get any new colors from it at all. You just can display more on the
screen.
–>Steve Bennett
I guess I thought that the shift to the right held the last bit; That's the way
I would have done it. It's certainly easy enough.
Ok, 16 grey levels.
–Ben-
How does an Amiga do 32 level gray scale? The way I remember it there
are 4 bits for each color, so there are 16 steps, i.e. 16 shades of grey. You
said "any current amiga". That implies that there is something new. Extra
halfbrite? I thought that that was rounded as well, so that half of FFF was
the same as half of EEE, so we'd still have 16 levels of grey. Either you are
wrong, I don't understand halfbrite, or something new has slipped by me. I'd
appreciate knowing which 😉
I may be wrong. I thought that the extra halfbright shifted the thing, as you
say, but that the bit that was shifted out to the right was retained. If it's
not, then there are only 16 grey levels, as you say.
However… if it's not, then that's really sad. it's such an easy thing to do.
I did an interface for the CoCo once that used an inter-pixel average to smooth
grey level images. The two incoming 4 bit words went into a dual four bit
adder; the adder had a four bit sum out, and carry. We used carry and the upper
three bits at the normal intensities, and the LSB as the 5th bit which had a
grey value of 1/2 the LSB. The bit is accurate in an averaging situation, of
course. The result was wonderful in that application.
I have to admit, it never even occured to me that CBM would design the thing so
that some of the useful information, already obtained within the available
bandwidth of the video accesses would be just thrown away. Oy!
–Ben-
It's easy to do ONLY if you have a 5-bit d-a at the other end, otherwise you
just can't do it.
Yes – but when you have a 4 bit d/a, a 5 bit one is an easy step away, so to
speak. I assummed (incorrectly, I gather) that they had done the obvious thing.
Guess not. :*)
–Ben-