shade area in a plot between x and y according to the value

I want to plot this picture

These are the data I have

x = [4.5;5;5.5;6;7;8;9;10];
y = (1:7)';
val = (0.1:0.1:1)'; 

Here is the sample of above data. Size of data is 7*7

        Y    X   value
        --------------
data = [1, 4.5, 0.1;
          ...
        2, 5, 0.2;
        6, 5.5, 1;
        7, 10, 0.5];

I do not know how to shade the area according to the value.

[Akira Agata]

That should be a heatmap function.

But I believe the data size of val does not match to your x and y.

[NA]

Thank you for your help.