MATLAB GUI: How do I pass image matrix into function

Hi,

So I'm trying to read the image and then pass it through a function so that I can perform image analysis with some defined parameters.

For the "Load Image" button here's the code:

% Button pushed function: LoadImageButton

function LoadImageButtonPushed(app, event)

[FileName, FilePath]= uigetfile('.TIF');

I=imread([FilePath FileName]);

imshow(I, 'Parent' , app.UIAxes); %Displays selected image onto original image

I would then need to define some paratmers (Filter Size, Threshold, Cut Cells Regions) before running my external function. Once you input the paramters and press "Compute", I'm hoping that it would go into my function that I've written (called trialfunction here):

function ComputeButtonPushed(app, event)

filter_size = app.FilterSizeEditField; %Input parameter

trialfunction(I_M,filter_size)

S = app.ValueEditField;

The "trial function" is just a simple range filter that manipulates the image (stored in a 2D matrix):

function[S]=trialfunction(I_M,filter_size);

I_bin_regions = rangefilt(I_M,ones(filter_size,filter_size));

S=sum(I_bin_regions,'all')

end

However, I'm having trouble linking the data from I (2D matrix) into my function. How can I "connect" the "Load Image" function with the "Compute Button" function?

Thanks so much!

Note: I have tried adding app.I.ImageSource = imread (...) but that doesn't work. Error message says "

Unrecognized method, property, or field 'I' for class 'imageprocessing'.

[Rik]

Did you make sure I is a property before trying app.I=?

[William Pang]

I'm a bit new to the GUI interface, so apologies if I'm asking stupid questions, but how would you make I a property? I know that the image is reading properly (since I'm able to display it without adding the "app.I", just as "I") but would appreciate any pointers on how to make "app.I" a property.

Answer 1

[Tommy]

In appdesigner, first make sure you are in code view:

Then in the code browser on the left side, go to the tab labeled Properties and select the green plus sign. The property will be private by default. If you want the property to be public (accessible from outside the app), you can click the down arrow and choose Public Property.

(edit) If you are calling imshow and rangefilt on this I, then I would use

app.I = imread (...)

where app.I is an array, rather than

app.I.ImageSource = imread (...)

where app.I is a uiimage.

[William Pang]

Thank you! That was very helpful!

However, I'm having trouble getting the output of my function (trialfunction (I_M,filter_size) to display in the "value" box. Any help would be appreciated!!

[Tommy]

Assuming that that value box is a numeric edit field stored in app.ValueEditField, try this:

s = trialfunction(I_M,filter_size);
app.ValueEditField.Value = s;

[William Pang]

Thanks again!! And just one follow up (just by using app.ValueEditField):

If the value of s, for instance, is showing 6.67819e+06, I get the error message:

Error setting property 'ValueEditField' of class 'imageprocessing':

Cannot convert double value 6.67819e+06 to a handle

[Tommy]

I believe you'd get that error message if you had

app.ValueEditField = s

You can't set app.ValueEditField, which has type matlab.ui.control.NumericEditField, to a double (i.e. a number). If you are hoping to set the edit field's value, you'd have to use

app.ValueEditField.Value = s;

Or did you use this line and still get that error?

[William Pang]

Yup, I get a different error.

Using just "app.ValueEditField":

It's weird because I am definitely getting a numerical value in the command window (so I know the function is working and something is passing through it) but doesn't seem to talk with the App Designer.

[Tommy]

Ah, there are two different types of edit fields in appdesigner, text and numeric. If you want to display numbers, your edit field needs to be numeric. Are you sure you chose the correct style when you created the user interface?