How to add gray to out of range in the colormap?

Hi,

How to add gray color to out of range colormap, inorder to have bettter visulaization. In the following code, I need gray color for values which are not between 10 to 60.

imagesc(xFocP,yFocP,Ax_map);
colormap jet;
colorbar;
caxis([10 60])

Answer 1

[DGM]

You might try something like this:

[x y z] = peaks(100);

surf(x,y,z);
shading flat
camlight

numcolors = 64;
g = [1 1 1]*0.8;
cmap = parula(numcolors);
cmap = [g; cmap; g];

cextents = [-4 5];
offset = range(cextents)*(size(cmap,1)/numcolors - 1)/2;
caxis(cextents + [-offset offset])

colormap(cmap)
colorbar

[Kalasagarreddi Kottakota]

Thank you

Answer 2

[Mathieu NOE]

coming too late in the show ....

hello

my 2 cents suggestion :

% dummy data 
N = 25;
Z = peaks(N);
Z = Z*5+35;
ZZ = Z;
ind = find(Z<10 | Z>60);
ZZ(ind) = 0;

% plot
figure
imagesc((1:N),(1:N),ZZ);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
n = 128; % dark grey => decrease n; light grey => increase n; 
tmp = [n n n]/255; % grey color
mymap = [tmp;jet(255)];     % my colormap
colormap(mymap);

hcb=colorbar('ver'); % colorbar handle
hcb.Limits = [10 60];
hcb.FontSize = 12;
hcb.Title.String = "Range";
hcb.Title.FontSize = 15;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[Kalasagarreddi Kottakota]

Thank you,

But when I change hcb.Limits = [10 60]; to hcb.Limits = [50 60], the colorbar shows like this instead of jet?

[Mathieu NOE]

this is my result if I do the same mod as you in my code

% dummy data 
N = 25;
Z = peaks(N);
Z = Z*5+35;
ZZ = Z;
ind = find(Z<10 | Z>60);
ZZ(ind) = 0;

% plot
figure
imagesc((1:N),(1:N),ZZ);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
n = 128; % dark grey => decrease n; light grey => increase n; 
tmp = [n n n]/255; % grey color
mymap = [tmp;jet(255)];     % my colormap
colormap(mymap);

hcb=colorbar('ver'); % colorbar handle
hcb.Limits = [50 60];
hcb.FontSize = 12;
hcb.Title.String = "Range";
hcb.Title.FontSize = 15;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[Kalasagarreddi Kottakota]

Ya, I got it, but the color bar does not realign to jet i.e. blue to red?

[Mathieu NOE]

Ok

so I changed my code to have colorbar and grey "synchronous"

is it working the way you want ?

with : caxis([10 60]) , I got this :

and with caxis([50 60]) , I got this :

% dummy data 
N = 25;
Z = peaks(N);
Z = Z*5+35;

% plot
figure
imagesc((1:N),(1:N),Z);
caxis([50 60])
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
n = 128; % dark grey => decrease n; light grey => increase n; 
tmp = [n n n]/255; % grey color
mymap = [tmp;jet(255);tmp;];     % my colormap
colormap(mymap);

hcb=colorbar('ver'); % colorbar handle
% hcb.Limits = [50 60];
hcb.FontSize = 12;
hcb.Title.String = "Range";
hcb.Title.FontSize = 15;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

[Kalasagarreddi Kottakota]

Perfect and thank you.

[Mathieu NOE]

My pleasure