Color scheme problem

Question

I have a problem in the color scheme in a 2D spectra.

After a lot of calculations, i can generate a picture like this

in the last part using this instructions

ListContourPlot[dat, ContourShading -> None, 
InterpolationOrder -> 3, 
Contours -> Delete[CNTRFT[dat], Length[CNTRFT[dat]]/2 + 1/2], 
ContourStyle -> CLRFT[dat], PlotRange -> {Ran[[1]], Ran[[2]], All}, 
DataRange -> Ran, ColorFunctionScaling -> False, Axes -> False]

ListDensityPlot[dat, PlotRange -> {Ran[[1]], Ran[[2]], All}, 
ColorFunction -> (Hue[.45 - #] &), ColorFunctionScaling -> False, 
DataRange -> Ran, InterpolationOrder -> 3, Axes -> False]

the color in the corners (aquamarine) are for zero value, blue and violet are for negative values and yellow and green for positive values. Now i need to clean this color, because i want to train a convolutional network to identify spectra. Then I need the spectra with a color scheme with white for the zero value. I try to use diferent forms as, for example change the Hue value as

(Hue[.45 - #, 0 - #, 1] &) 

or

(Hue[.45 - #, 0 + #, 1] &) 

but, i only obtain the negative or positive values and zero.

I have this problem for a time and i need to continue. any suggestions?

Thanks a lot for the help.

Regards.

Answer 1

You can create color schemes with white in the middle using Blend:

sample[blendColors_] := Table[
  Blend[
   blendColors,
   Rescale[x, {-1, 1}]
   ], {x, {-1, -0.5, 0, 0.5, 1}}
  ]

sample[{Red, White, Blue}]

sample[{Purple, Blue, Cyan, White, Green, Yellow, Orange}]

Another example where I don't rely on the number of colors on either side of White:

sample[{{0.1, Purple}, {0.2, Blue}, {0.5, White}, {1, Red}}]

And finally one with values that are negative and haven't been rescaled before being passed to Blend:

Table[
 Blend[
  {{-1, Purple}, {-0.5, Blue}, {0, White}, {1, Red}},
  x
  ], {x, {-1, -0.5, 0, 0.5, 1}}
 ]