How to set specific colors in a 2D histogram to some entries

ROOT
1

Hi, I need to change the colour in a 2D histogram, just to the values equal to zero.
When the histogram is drawn the colour is Green and changes depending on the values I input, so I would like to set a different colour for some reference values (those equal to zero with colour white). Is this possible in ROOT?
Here is a piece of the code:

gStyle->SetPalette(1);
TH2F *respsiphi = new TH2F("respsiphi","#psi vs #phi",50,-180,180,50,-90,90);
respsiphi->Fill(phi,psi,value);
respsiphi->Draw("colz");

Thank you for your help.

2

Example:

{
   TCanvas *c  = new TCanvas("c","Contours",600,0,600,600);
   TF2 *f2 = new TF2("f2","(sin(x)/x)*(cos(y)*y)",-3,3,-3,3);              

   Int_t Number = 6;
   Double_t Red[Number]   = { 0.00,  0.00, 1.0,     1.0, 0.00, 0.50 };
   Double_t Green[Number] = { 0.01,  0.50, 1.0,     1.0, 0.50, 0.07 };
   Double_t Blue[Number]  = { 0.50,  0.09, 1.0,     1.0, 0.09, 0.07 };
   Double_t Stops[Number] = { 0.00,  0.49, 0.495, 0.505, 0.51, 1.00 };


   Int_t nb=50;
   TColor::CreateGradientColorTable(Number,Stops,Red,Green,Blue,nb);
   gStyle->SetNumberContours(nb);
   f2->Draw("colz");
}

c.gif596×572 17.5 KB

3

Hi Couet,
thank you for your help, I understood how to do it!!!
Cheers,
Eric