How can I link the color of an image to a defined temperature?

I'm working on this image as following:

RGB = imread('Flame1.jpg');
[X,map] = rgb2ind(RGB,3);
imagesc(X) 
cmap = colormap(map);
colormap('hsv')
axis off
axis image

c = colorbar; 
c.Limits = [-4 4];
c.Ticks = [-4 1 4];
c.TickLabels = {'800\circ C','900\circ C','1000\circ C'};

In this way on the colorbar to each temperature (800 °C, 900 °C and 1000 °C) it will correspond red, green and blue respectively as it's showed in the colormap. However, what I did is a manual assignement since I customize the colorbar manually. I was wondering if there is a way to link the colors of the colorbar and the colormap to the temperature.

If not, is there a better way to link the colors to the assigned temperature?

[Adam Danz]

FWIW, I don't see anything wrong with your approach.

[Enne]

I would like to create a colorbar in which everytime there is green it will be connected to 900°C (and the same for red to 800°C and blue for 1000°C). The fact is that this is a test image I'm using but I have to analyze different pictures and it will take me a lot of time to manually connect the temperature to the color in the colorbar.

[Adam Danz]

I understand what you're describing but I have to think about it and I don't have time right now to develop a solution.

[Enne]

Don't worry, thank you for your time!

[Adam Danz]

I came across this file exchange submission today that may be helpful to you

https://www.mathworks.com/matlabcentral/fileexchange/29638

[Enne]

Thank you @Adam Danz, I tried to run this code with the examples given by the user itself but apparently it doesn't work

Answer 1

[Sanju]

Hi Enne,

I understand that you want to link the colour of an image automatically to a defined temperature,

Currently there is no built-in functionality in MATLAB that directly links the colors of the colorbar and the colormap to the temperature values. The manual assignment you have done is a common approach in such cases.

However, if you have a specific temperature-to-color mapping that you would like to achieve, you can create a custom colormap using the colormap function. By defining a colormap that smoothly transitions between colors, you can visually represent the temperature values with corresponding colors.

To create a custom colormap you may refer to the following code:

% Define the temperature values and their corresponding colors 
temperature = [-4, 1, 4]; 
colors = [1 0 0; 0 1 0; 0 0 1]; % Red, Green, Blue 

% Create a custom colormap 
custom_cmap = interp1(temperature, colors, linspace(-4, 4, 256));  

% Apply the custom colormap 
colormap(custom_cmap); 

%Add your code here
....

You can also refer to the following link for more information,

https://www.mathworks.com/help/matlab/ref/colormap.html

Hope this helps!