Imagesc and plot on the same graph with two scale

Hello, I am using imagesc to create a picture with data. I am after using plot to plot some data, but the problem is that they don't have the same scale. So i think i need to add a new axis. But the matlab help was not very helpful for imagesc and plot for that.. Can you help me ?

Thanks

[Clément]

I was doing

figure
imagesc(....)
hold on
plot(...)

Answer 1

[emehmetcik]

Hi,

You can use imagesc() function with x, y and z inputs. These inputs does not necessarily be the same size as required by 3D plot functions (surf, mesh etc.). For instance;

load clown

imagesc(1:10, [1, 5], X); 

hold on;
x = linspace(1, 10, 5);
y = linspace(1, 5, 5);

plot(x, y, 'r', 'linewidth', 2)
plot(x, y(end:-1:1), 'r', 'linewidth', 2)

colormap(map)
axis equal

Note that the loaded image data (X) is 200x320 pixels. However you can control the aspect ratio using proper values for x and y axes limits in the imagesc function. I hope this helps.

[Geoff Hayes]

Clément's answer moved here

In fact, I am showing a picture with imagesc the size of this image is 400x400. I am showing a plot : x :0->400(same size as picture) y :0->1

I just want to put them together on the same graph. But the problem is as there is only one Y scale, data from the plot, are not shown. Because scale is from 0 to 400 and date from plot are from 0 to 1...

I hope you can help me

[emehmetcik]

You may try plotyy function of Matlab, together with imagesc.

clear 
close all;

load clown

% X = randn(400);

xImage = [0, 400];
yImage = [0, 400];

xData = linspace(0, 400, 5);
yData = linspace(0, 1, 5);

hold on;
h = plotyy(xImage, yImage, xData, yData);
set(h(1), 'ydir', 'reverse')

imagesc(xImage, yImage, X); colormap(map);

You can use surf function as well if the axis directions irritate you :)

    clear 
    close all;

    X = randn(400);

    xImage = [0, 400];
    yImage = [0, 400];

    [yLim, xLim] = size(X);

    xData = linspace(0, 400, 5);
    yData = rand(1, 5);
    yData = yData - min(yData);
    yData = yData / max(yData);

    hold on;
    h = plotyy(xImage, yImage, xData, yData);

    axis(h(1), [0, 400, 0, 400])

    [x, y] = meshgrid(0:399, 0:399);
    surf(x, y, ones(size(x)), X); shading flat

    view(2)