MATLAB Answers

imcontrast - how to return the level values?

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arnold
arnold on 9 Dec 2013
Answered: Image Analyst on 11 Dec 2013
Hi!
I have been using imcontrast
quite a bit over the years as it is a very handy tool for users to visibly adjust the threshold level for image segmentation. Here is my standard function:
im2bw(fn_image_leveling(testimage), 0.5);
function out = fn_img_leveling(img)
h=figure;
imagesc(img); colormap(hot);
axis image;
uiwait(imcontrast); % set levels
out = getimage(h);
out(out==0)=nan;
close(h);
In my current project I want to let the user set a threshold value for the first image and then apply it to many images. I can't seem to figure out though, how to get the threshold value a user sets using imcontrast. The way I see it the function is not intended to be used like this though :(
Does anyone have an idea how to solve this? I really need a live preview of the adjustable thresholding for it to work.
kind regards, Arnold

Answers (2)

Image Analyst
Image Analyst on 11 Dec 2013
See my interactive thresholding app: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862 It returns the values after which you can use them in imadjust() to process the rest of the images in batch mode.
Otherwise it looks like you'll have to ask the user to input the values via inputdlg() so that you can then use imadjust().

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Mitchell Anderson
Mitchell Anderson on 30 Oct 2018

I find them buried deep in the object hierarchy.

        temp = imcontrast;
        ContrastMax = str2num(temp.Children(1).Children(3).Children.Children(2).Children.Children(2).Children(2).String)
        ContrastMin = str2num(temp.Children(1).Children(3).Children.Children(2).Children.Children(2).Children(5).String)

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