temperature and gray level

is there any relation between gray level and thermal image?

[KSSV]

What do you mean by a relation?

[monika SINGH]

as in if gray level increses the temperature also increses or decreses??

is there any relation like this

[Rik]

In general, yes. The specifics will depend on you thermal camera setup.

[monika SINGH]

do you have any document proving this fact?

[Rik]

No, but it seems common sense to me. If you have a temperature sensor, the value it returns should increase for increasing temperature. (unless the mapping is reversed, which should be in your camera documentation)

Answer 1

[KSSV]

I hope this demo code might help you:

N = 100 ; 
x = rand(N,1) ; 
y = rand(N,1) ;
s = rand(N,1) ;   % Say intensity 
% Assign colors 
the_range=range(s);          % find range of data
min_val = min(s);            % find maximum value of data
max_val = max(s) ;           % find minimum value of data
idx = floor(((s-min_val)/the_range)*63)+1; 

p = colormap(gray) ;
col = p(idx,:) ; 

subplot(121)
scatter(x,y,30,col,'filled')
colorbar
subplot(122)
scatter(x,y,30,s,'filled')
colorbar