[Coco] Color Error in VCC
robert.gault at att.net
Thu Mar 8 11:02:18 EST 2012
Luis Fernández wrote:
> I found a mistake in the colors emulated by VCC.
> he error is basic and wonder to occur.
> A simple test program is
> 10 CLS
> 20 FOR A=0 TO 255
> 30 POKE 1024+A,A
> 40 NEXT
> 50 GOTO 50
> Apparently my right colors are not correct
> coconut lit my TV and found the following
> 0 Green
> 1 Yellow
> 2 Dark Blue
> 3 Purple or violet
> 4 White
> 5 green somewhat darker
> 6 Light blue, purple something
> 7 Orange
Whatever you are seeing, it is not the result of VCC. I just ran a test with a
US Coco3 using both RGB and Composite 60Hz monitors. Before running your
program, either the RGB or CMP commands were used to get an appropriate color
set. The colors displayed on the matching monitor were a very close match to the
colors displayed by VCC 1.42 on a Samsung SyncMaster 204B digital monitor. The
CMP and RGB monitor colors were very close to each other but not a perfect
match, starting with the appropriate color set.
Now with the real hardware, it was necessary to adjust brightness, contrast,
color intensity, and tint. If that was not done, the colors were not quite what
they should have been. That should not be a surprise as the Coco can't exactly
match CMP and RGB colors given the small range of possible colors.
The Coco3 and therefore VCC default to the CMP color set. There may be small
differences in color between NTSC and PAL sets or even 60 and 50Hz units. Your
program does not force the use of a specific color set, and it should if you
want any chance of getting appropriate colors.
More information about the Coco