According to page 176 of Compute's First Book of VIC:
"The VIC is a superior CRT controller for a B/W monitor due to the varying levels of luminance required for a color [sic ] picture. VIC can produce varying shades of gray [sic ]".
* SICs added by me to make fun of US spelling.
Anyway, does this mean that there is a way for the VIC-20 to produce gradients of grey? Has this ever been implemented in a VIC-20 program? I remember the C64 offered about 4 shades of grey and that was very useful for making smoothly transitioning greyscale images.
On a monochrome display, the various colours display as shades of grey. I think that that is all that the authors were saying. In other words, pick one: colour or grey. You can't have both.
PhotoJim wrote:On a monochrome display, the various colours display as shades of grey. I think that that is all that the authors were saying. In other words, pick one: colour or grey. You can't have both.
Thanks. Yeah, after re-reading it a few times I figured that's probably what they meant. Would be interesting to experiment with this to do a greyscale picture display program (would involve turning down the COLOUR setting on your monitor or TV).
FWIW, a talented C-64 artist I knew drew a couple pictures that were meant to be viewed in black & white using this method. I think early VIC-IIs have 5 different luminance values, while the later VIC-IIs have 9 (something like that, anyway).
Any idea how many different values the VIC has? Did it vary with revisions?
I suppose it depends on how you have trimmed the potentiometers.
On my PAL VIC-20 using RF cable, blue and red almost look the same when I turn down saturation, but the other colours display as unique levels of grey, which would make about six or seven levels, a little depending on which background colour you use.
Blue, Red
Purple, Orange
Green, Light blue
Light red (pink)
Cyan, Light orange, Light purple
Yellow
Light green
Light cyan
Light yellow
White
Well, that is a very non-scientific way to put it. IIRC, Jeff-20 is colour blind (?), maybe he can describe how he interpret the different colours, or does colour blindness work in different ways than using a B/W television?
I am colour (sic ) blind. I hardly think about it unless I am creating something for the VIC. I try hard to make sure the colors are what the user would expect.
Still, without seeing what you see, it would be difficult for us to compare notes. Especially since I was born this way and really don't conceptually understand just what color is in any meaningful kind of way. I suppose for you it would be like discussing subtle differences in various types of magnetic fields.
I have figured out that if one has a black and white tv, one could see what I see as I can barely tell the difference between the two.
I think the most common diagnosis is red/green colour "blindness", but admittingly, it is hard to understand how it appears. It is said that dogs can't see colours (or at least some breeds), but I'm unsure how it has been verified and whether you would interpret colours like a dog does.
But can you compare the intensity of colours, and do you get an order similar to what I posted?
As you pointed out, juxtaposition makes a big difference. Depending on the background, I may confuse tones. Because I hardly think about it, the order doesn't really register a visual image I could verify. I'll have to go to the VIC and put them on a white background to see.
] picture. VIC can produce varying shades of gray [sic 
) blind. I hardly think about it unless I am creating something for the VIC. I try hard to make sure the colors are what the user would expect.