[Gnuplot-info] log color bar: out of range data --> invisible

[theozh <th...@gm...>]

Hi there,

In a matrix plot with logarithmic colorbar scale it is clear that
negative numbers cannot be displayed.

set logscale cb
set cbrange[1e-10:1e-4]
set palette rgbformulae 7,5,15
plot "Matrix.dat" matrix with image

Therefore, I would like to display the negative values as "missing
values", i.e. invisible (white or transparent).
However, it seems that gnuplot gives these negative datapoints the color
of the maximum value instead of the minimum value or treating it as
missing data. How can I achieve that?

Thanks for any hints. Theo.