How to callback same function for changes in multiple uiobjects?

I am creating a uifigure-based app programatically for de-noising the noisy images. The code for which is as follows:

function filteredImage
fig = uifigure;
g = uigridlayout(fig,[3 2]);
g.RowHeight = {30,30,'1x'};
g.ColumnSpacing = 10;
filterLabel = uilabel(g,"Text","Filter Type","WordWrap","on","FontSize",18,"FontWeight","bold");
filterLabel.Layout.Row = 1;
filterLabel.Layout.Column = 1;
% Choose type of filter to be displayed
filterType = uidropdown(g,"Editable","on","Position",[0 50 20 10],"FontSize",18);
filterType.Layout.Row = 1;
filterType.Layout.Column = 2;
filterType.Items = ["Arithmetic Mean Filter",
             "Geometric Mean Filter",
             "Weighted Average Filter"];

kernelDimlabel = uilabel("Parent",g,"Text","Kernel Dimensions","FontSize",18,"FontWeight","bold");
kernelDimlabel.Layout.Row = 2;
kernelDimlabel.Layout.Column = 1;
% Set the kernel size (since it is a square matrix, #rows = #columns)
kernelDim = uispinner("Parent",g,"Step",2,"Value",3,"Limits",[3 11],"FontSize",18);
kernelDim.Layout.Row = 2;
kernelDim.Layout.Column = 2;
% Noisy image displayed
im1 = uiimage(g,"ImageSource","poutsalt & pepper.png");
im1.Layout.Row = 3;
im1.Layout.Column = 1;
% Filtered image displayed
im2 = uiimage(g);
im2.Layout.Row = 3;
im2.Layout.Column = 2;

% Here, filterImage updates im2 whenever the value of filterType changes
filterType.ValueChangedFcn = @(src,event)filterImage(src,event,im1,im2,filterType,kernelDim);
% I want to update im2 when either the value of filterType changes OR when
% kernelDim changes
end
function filterImage(src,event,im1,im2,filterType,kernelDim)
    kDim = kernelDim.Value;
    I = imread(im1.ImageSource);
    I_name = erase(im1.ImageSource,".png");
    incr = floor(kDim/2);
    im1_padded = double(padarray(I,[incr incr],0,'both'));
    [r,c] = size(I);
    
   
    switch filterType.Value
        case "Arithmetic Mean Filter"
            kernel = double(ones(kDim));
            for i=1:r
                for j=1:c
                    I_filtered(i+incr,j+incr) = (1/(kDim*kDim))*sum(sum(kernel.*im1_padded(i:i+kDim-1,j:j+kDim-1))); 
                end
            end
            ext = "_amf"+"_"+ string(kDim) + ".png";
        case "Geometric Mean Filter"
            kernel = double(ones(kDim));
            for i=1:r
                for j=1:c
                    I_filtered(i+incr,j+incr) = prod(prod(kernel.*im1_padded(i:i+kDim-1,j:j+kDim-1))).^(1/(kDim*kDim)); 
                end
            end
            ext = "_gmf"+"_"+ string(kDim) + ".png";
        case "Weighted Average Filter"
            if kDim == 3
                kernel = (1/16)*[1 2 1;
                                 2 4 2;
                                 1 2 1];
            else 
                kernel = (1/52)*[1 1 2 1 1;
                                 1 2 4 2 1;
                                 2 4 8 4 2;
                                 1 2 4 2 1;
                                 1 1 2 1 1];
            end
            for i=1:r
                for j=1:c
                    I_filtered(i+incr,j+incr) = sum(sum(kernel.*im1_padded(i:i+kDim-1,j:j+kDim-1))); 
                end
            end
            ext = "_waf"+"_"+ string(kDim) + ".png";
    end   
    I_filtered = uint8(I_filtered);
    filteredImagePath = strcat(I_name,ext);
    imwrite(I_filtered,filteredImagePath);
    im2.ImageSource = filteredImagePath;
end

As of now I am getting the filtered image output. Initially there's no image in im2. But it appears only after I change the kernelDim followed by filterType. One obvious way is to explicitly write the code for initial values, but I want the function filterImage to somehow do it.

Please suggest techniques to do the same in an efficient manner.

Answer 1

[Jaimin]

Hi @Amitvikram

The“filterImage”function can be utilized for initialization of “im2” with some minor modifications to the code.

I have attached the code here for better understanding.

function filteredImage
    fig = uifigure;
    g = uigridlayout(fig,[3 2]);
    g.RowHeight = {30,30,'1x'};
    g.ColumnSpacing = 10;
    
    filterLabel = uilabel(g,"Text","Filter Type","WordWrap","on","FontSize",18,"FontWeight","bold");
    filterLabel.Layout.Row = 1;
    filterLabel.Layout.Column = 1;
    
    % Choose type of filter to be displayed
    filterType = uidropdown(g,"Editable","on","Position",[0 50 20 10],"FontSize",18);
    filterType.Layout.Row = 1;
    filterType.Layout.Column = 2;
    filterType.Items = ["Arithmetic Mean Filter",
                 "Geometric Mean Filter",
                 "Weighted Average Filter"];
    
    kernelDimlabel = uilabel("Parent",g,"Text","Kernel Dimensions","FontSize",18,"FontWeight","bold");
    kernelDimlabel.Layout.Row = 2;
    kernelDimlabel.Layout.Column = 1;
    
    % Set the kernel size (since it is a square matrix, #rows = #columns)
    kernelDim = uispinner("Parent",g,"Step",2,"Value",3,"Limits",[3 11],"FontSize",18);
    kernelDim.Layout.Row = 2;
    kernelDim.Layout.Column = 2;
    
    % Noisy image displayed
    im1 = uiimage(g,"ImageSource","poutsalt & pepper.png");
    im1.Layout.Row = 3;
    im1.Layout.Column = 1;
    
    % Filtered image displayed
    im2 = uiimage(g);
    im2.Layout.Row = 3;
    im2.Layout.Column = 2;
    
    % Define the function to update the filtered image
    updateFilteredImage = @(src,event)filterImage(src,event,im1,im2,filterType,kernelDim);
    
    % Assign ValueChangedFcn to both filterType and kernelDim
    filterType.ValueChangedFcn = updateFilteredImage;
    kernelDim.ValueChangedFcn = updateFilteredImage;
    
    % Call filterImage initially to display the image with default values
    filterImage([],[],im1,im2,filterType,kernelDim);
end

function filterImage(~,~,im1,im2,filterType,kernelDim)
    kDim = kernelDim.Value;
    I = imread(im1.ImageSource);
    I_name = erase(im1.ImageSource,".png");
    incr = floor(kDim/2);
    im1_padded = double(padarray(I,[incr incr],0,'both'));
    [r,c] = size(I);
    
    switch filterType.Value
        case "Arithmetic Mean Filter"
            kernel = double(ones(kDim));
            for i=1:r
                for j=1:c
                    I_filtered(i+incr,j+incr) = (1/(kDim*kDim))*sum(sum(kernel.*im1_padded(i:i+kDim-1,j:j+kDim-1))); 
                end
            end
            ext = "_amf"+"_"+ string(kDim) + ".png";
        case "Geometric Mean Filter"
            kernel = double(ones(kDim));
            for i=1:r
                for j=1:c
                    I_filtered(i+incr,j+incr) = prod(prod(kernel.*im1_padded(i:i+kDim-1,j:j+kDim-1))).^(1/(kDim*kDim)); 
                end
            end
            ext = "_gmf"+"_"+ string(kDim) + ".png";
        case "Weighted Average Filter"
            if kDim == 3
                kernel = (1/16)*[1 2 1;
                                 2 4 2;
                                 1 2 1];
            else 
                kernel = (1/52)*[1 1 2 1 1;
                                 1 2 4 2 1;
                                 2 4 8 4 2;
                                 1 2 4 2 1;
                                 1 1 2 1 1];
            end
            for i=1:r
                for j=1:c
                    I_filtered(i+incr,j+incr) = sum(sum(kernel.*im1_padded(i:i+kDim-1,j:j+kDim-1))); 
                end
            end
            ext = "_waf"+"_"+ string(kDim) + ".png";
    end   
    
    I_filtered = uint8(I_filtered);
    filteredImagePath = strcat(I_name,ext);
    imwrite(I_filtered,filteredImagePath);
    im2.ImageSource = filteredImagePath;
end

I hope this will be helpful.