Re: An X11 palette issue, approximate_palette

[Daniel J S. <dan...@ie...>]

Ethan Merritt wrote:
> On Thursday 23 March 2006 12:43 pm, Daniel J Sebald wrote:
> 
>>Here is a small issue with the palette in X11.
>>
>>However, the X11 terminal produces a color box with an artifact at -5
>>and 0.  See the attached PNG "Screenshot-Gnuplot-4-palfunc.png".
> 
> 
> I think this may be a problem with your x11 configuration.
> I see no such artifact on my display (screen capture attached).
> I do, however, see more orange than expected at the boundary 
> between red and green in the plot itself.

I should have emphasized that this is for the demo in the most recent CVS.  My mistake.  An update to the demo pm3dcolors.dem was recently checked in to handle exactly the issue you have found.  That orange strip is the result of defining the functions by flipping the step function in time.  Because it occurs only when the functions are sampled right at 0.25, that orange strip would appear in some terminals but not others.  Sometimes in the color box, sometimes not.

The updated demo implements these functions as

theta(x) = x<0 ? 0 : 1
r(x) = 4*x*(1-theta(x-0.25))
g(x) = 0.5*theta(x-0.25)*(1-theta(x-0.5))
b(x) = x

i.e., flips the step function in amplitude.  The intent is to minimize the effect of now to properly define the value of the function right at the discontinuity.

So, please try the most recent version of the demo.

Thanks,

Dan