select ROI, threshold it and remove small objects - App designer
2 views (last 30 days)
Jane Bat on 3 Mar 2022
In the attached app designer file I select a ROI, threshold it and remove small objects from binary image. I have encounter two problems: 1) the threshold silder value is not dynamic, 2) the remove object does not work properly (I get a black square).
Any idea why and how it can be solved?
Abolfazl Chaman Motlagh on 3 Mar 2022
about the first problem:
you overwrite the app.Icrop on app.I every time the slider changes. so after first time, it goes completely black. you should keep app.I and for representing the image create a local image for ploting. replace the below code with the respected part of yours for this solution. or you could have a backup for app.I, or you could create a new variable. if at the end you want to save the image it's better to have another variable for changed image.
function otsuthresholdSliderValueChanged(app, event)
value = app.otsuthresholdSlider.Value;
app.Icrop = app.I(app.row1 : app.row2, app.col1 : app.col2, :);
app.Itemp = imbinarize(app.Icrop,value)*255;
app.Icrop = app.Itemp;
I_local = app.I;
I_local(app.row1 : app.row2, app.col1 : app.col2, :) = repmat(app.Itemp, [1 1 size(app.I,3)]);
for second problem:
the function bwareaopen is a function which act on binary images and remove connected components with less than specific number of pixel. the word remove here means replace the pixels with 0. your image ('peppers.png') is not a binary image. but still your usage of this function is wrong. the all ROI you select become 0 after using this function.