MATLAB: How to have colourful contours superimposed on a grayscale (imshow) background

colorbarcontourgrayscale backgroundimshow

Hi! I need to create contours (with the ordinary colorbar) superimposed on a grayscale image, which I have plotted using imshow. The contours tend to appear in white. Is there any way to give them colours?

Here is my code:

Brain=load('Raw.mat');

background=mat2gray(Brain(:,:,26));

figure

imshow(background)

hold on

densities=[1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8000];

contour(volume(:,:,26),densities)

hold off

Best Answer

Here's one way. If you turn the background matrix into RGB values, imshow won't try to attach the background image to the current colormap.

bg = ind2rgb(imread('cameraman.tif'),gray(256)); 
imshow(bg)
hold on
contour(peaks(256))

Related Solutions

MATLAB: How to add a ‘colorbar’ and set ‘clim’ to a colour image overlaid on a grey level image

I asked the same thing a few years ago :)

http://www.mathworks.com/matlabcentral/answers/11695-how-to-show-a-colorbar-of-a-certain-range

MATLAB: How to save all opened window Figure (imshow) with specified name and folder

Diah - it isn't clear to me why you have the inner for loop

for k = 1 : length(theFiles)
    baseFileName = theFiles(k).name;
    fullFileName = fullfile(myFolder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    % Now do whatever you want with this file name,
    % such as reading it in as an image array with imread()
    currentImageArray = imread(fullFileName);
    currentImage{k}=currentImageArray;
    
    for i = 1 : 7
        outputFolder = 'D:\DIAH\[MATLAB]cv1-fingerspelling-recognition-master\cv1-fingerspelling-recognition-master\Hasil Percobaan Lab';
        outputFileName = fullfile(outputFolder, ['Hasil Citra Lab_' num2str(i) '.jpg']);
        imwrite(currentImage{k}, outputFileName);
        % drawnow; % Force display to update immediately.
    end
end

but it does explain why you are writing out the same file seven times and why all correspond to the last image that you read in. Note how in the outer loop you iterate over all jpgs (from the folder). Then, for each of these images, you have an inner loop that creates seven files (all with the same image currentImage{k}) across seven files named "Hasil Citra Lab_1.jpg", "Hasil Citra Lab_2.jpg",..., "Hasil Citra Lab_7.jpg". That means that on every iteration of the outer loop, you will overwrite the contents of these seven files (since they don't depend upon the k variable) with the image that has been read on the current iteration of the outer loop.

If you want to make sure that you don't overwrite the files, then you could add k to the file name

outputFileName = fullfile(outputFolder, sprintf('Hasil Citra Lab_%d_%d.jpg', k, i));

Otherwise, you may want to verify if you really need that inner loop (I'm not sure why you need to write the same image to seven different files).

Best Answer

Related Solutions

MATLAB: How to add a ‘colorbar’ and set ‘clim’ to a colour image overlaid on a grey level image

MATLAB: How to save all opened window Figure (imshow) with specified name and folder

Related Question