TOPIC ---------------------------------------------
Sometimes the color selection works fine, and sometimes it does not. It seems
to work OK on the primary colors along the outer rim of the color wheel.
However, when I move in toward the center, choose a color, say OK, I get a
completely different color than what I chose. Sometimes the color does not
change at all--it stays a dark gray.
Another problem is that when you change the color successfully and restart, the
color returns to the color before the change! I tried this on an 8-bit video
card system, and it worked fine. So, at this point, it seems to be a problem
with 4-bit video systems. This is the first color problem I have encountered,
but it is easy to duplicate on a 4-bit video system by going into the "color"
option in the Control Panel and making various changes to the default color. I
am running System 6.0.3.
Is there a workaround for this, or is this a problem being addressed by a new
update for the operating system?
DISCUSSION ---------------------------------------------
The situation you are describing is a direct result of the number of colors
that can be displayed on a screen at one time. With a 4-bit video card, this
number of colors is a total of 16 at any one time.
The Color Picker will display any one of the 16.7 million colors that Color
QuickDraw is capable of generating. It does this by altering its color lookup
table on the fly as you request different colors. When you click the OK
button, the values chosen are returned to the calling program (in this case the
Color Control Panel Device). The program then uses this value; the Color CDEV
uses it to set the color of text selections. However, the way this color
actually is displayed depends on the current color lookup table (CLUT) in use,
which has no bearing on what was being used in the Color Picker Package. In
most cases, the CLUT being used is the standard system CLUT. The color chosen
in the Color Picker is mapped to the closest available color in the system
CLUT, and that color is the one that you actually see on the screen.
When you only have 16 colors available on the screen at one time, it is likely
that you will not get the color displayed in the Color Picker, and, quite
often, you see the exact same color you had on the screen before--even though
the actual RGB values specified are very different. This same sequence of
events occurs with an 8-bit video card. The difference is that with 256 colors
on the screen at one time, you have more colors to map to in the system CLUT,
and it seems as though you are getting the actual values requested.