Unable to do subtraction of images in GUI

Question

Warid Islam 2021-6-9

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/852370-unable-to-do-subtraction-of-images-in-gui

评论： Warid Islam 2021-6-14

Hi,

I have built a matlab GUi where I load two separate sets of images in two different axes. I want to subtract each of the both sets of images from each other and display the result in another image axes(axes3). I would browse through each set of images from the first two image axes using a image slider. Their corresponding subtraction result would be displayed in the third axes. However , I am getting an error message.

function pushbutton3_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton3 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
value1=handles.value1;
orig_imgs1 = handles.InputImage1;
output_img1=handles.InputImage2;
handles.dblSubtractedImage = {};
    [rowsorig_imgs1 colsorig_imgs1 numberOfColorChannelsorig_imgs1]=size(orig_imgs1);
     [rowsoutput_img1 colsoutput_img1 numberOfColorChannelsoutput_img1]=size(output_img1);
if rowsoutput_img1 ~= rowsorig_imgs1 || colsorig_imgs1 ~= colsoutput_img1
    output_img1 = imresize(output_img1, [rowsorig_imgs1 colsorig_imgs1]);
end
   dblSubtractedImage = (orig_imgs1{value1}) - (output_img1{value1});
 
   imshow(dblSubtractedImage,'parent',handles.axes3);
   handles.dblSubtractedImage{end+1}= dblSubtractedImage;
guidata(hObject, handles);
end

I get the following error message:

Error using imresize>parsePreMethodArgs (line 379)

Invalid input syntax; input image missing from argument list.

Error in imresize>parseInputs (line 273)

parsePreMethodArgs(varargin, method_arg_idx, first_param_string_idx);

Error in imresize (line 152)

params = parseInputs(args{:});

Error in ng>pushbutton3_Callback (line 226)

output_img1 = imresize(output_img1, [rowsorig_imgs1 colsorig_imgs1]);

Error in gui_mainfcn (line 95)

feval(varargin{:});

Error in ng (line 42)

gui_mainfcn(gui_State, varargin{:});

Error in

matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)ng('pushbutton3_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback.

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Answer 1

Image Analyst 2021-6-12

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https://ww2.mathworks.cn/matlabcentral/answers/852370-unable-to-do-subtraction-of-images-in-gui#answer_723515

在 MATLAB Online 中打开

What is this????

InputImage2 = imresize(InputImage2(value1), [rowsInputImage1 colsInputImage1]);

You're saying the image is InputImage2(value1). So what is value1? Is it an integer or a vector? So if value1 is an integer then you're basically using it as the linear index into the InputImage2 image, which gives you only a single pixel. Then you blow up this pixel to a whole image with imresize - so now you have a totally uniform image. Now you subtract that from InputImage1 and it will just look like a dark version of InputImage1. However you used [] in imshow() to scale the image to fit the dynamic range so of course it will look identical to InputImage1.

Try

InputImage2 = imresize(InputImage2, [rowsInputImage1 colsInputImage1]);

and when you subtract, cast the images to double or else negative numbers will get clipped.

dblSubtractedImage = double(InputImage1) - double(InputImage2);

or you can use imabsdiff(), which essentially flips negative numbers positive.

dblSubtractedImage = imabsdiff(InputImage1, InputImage2);

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Warid Islam 2021-6-14

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Hi @Walter Roberson,

I tried the process separately. I am getting the result. However, the problem is that I am unable to implement the process in GUI. Please find the code below:

I= rgb2gray(imread('TM19.jpg'));
figure,imshow(I)
x=300; y=340;
a=imgaussfilt(I,2);
b=adapthisteq(a);
m=regiongrowing_MLT(b,x,y,12);
m=imfill(m,'holes');
% figure,imshow(m)
bw=imbinarize(m);
bw=bwareafilt(bw,1);
% figure,imshow(bw)
I1 = imresize(m,.5);  %-- make image smaller 
m1 = imresize(bw,.5);  %     for fast computation
seg = region_seg(I1, m1, 30); %-- Run segmentation
img_class=class(I);
fill=cast(seg,img_class);
seg1=fill.*I1;
figure,imshow(seg1); title('Global Region-Based Segmentation');
[rowsI colsI numberOfColorChannelsI]=size(I);
[rowsseg1 colsseg1 numberOfColorChannelsseg1]=size(seg1);
if rowsseg1 ~= rowsI || colsI ~= colsseg1
    seg1 = imresize(seg1, [rowsI colsI]);
end
dblSubtractedImage = (I) - (seg1);
figure, imshow(dblSubtractedImage, []);

While implementing the process in the GUi, I get the the ROi as black but the background is white. Whereas, while using this code separately, I get the desired result. The ng.fig and ng.m in the initial attachment is my GUI.

Walter Roberson 2021-6-14

ng.m

I have attached a cleaner version of ng.m that prevents some of the error messages, and is smarter about remembering directories.

You would have seen all-black for the result if the original image and the segmented image were the same. In the case of TM19, you did not happen to provide the segmented image, but I accidentally reproduced that problem because I had been a bit careless when I adapted the directory controls. I modified the code so that in the case that the two are identical, that a specific warning message is raised.

You might notice that some of the buttons are not always available. This was done because you set up variables in some pushbuttons that are needed by later pushbuttons: in such a case you should disable the pushbuttons until conditions are right for the buttons to work.

The directory prompts were a bit confusing for the case where the hard-coded directories were not found. I cleaned that code up some, making it clearer in the prompt as to which directory was being asked for.

Warid Islam 2021-6-14

在 MATLAB Online 中打开

Hi @Walter Roberson,

That really helped a lot. I have one last query. I tried to save the image displayed in image axes 3 everytime when I browse through the slider. I used a SAVE button to do the operation. However, I am getting an error message.

function pushbutton4_Callback(hObject, eventdata, handles)
handles = guidata(hObject);
        value1=handles.value1;
dblSubtractedImage=handles.dblSubtractedImage;
startingFolder = 'D:\regionGrowing_MLT'; % Or "pwd" or wherever you want.
if ~isfolder(startingFolder)
	startingFolder = pwd;
end
defaultFileName = fullfile(startingFolder, '*.jpg');
[baseFileName, folder] = uiputfile(defaultFileName, 'Specify a file');
if baseFileName == 0
	% User clicked the Cancel button.
	return;
end
% If they entered an extension, throw it away because (for some reason)
% we want to force it to be JPG format, not whatever other format they may have entered.
[~, baseFileNameNoExt, ext] = fileparts(baseFileName);
fullFileName = fullfile(folder, [baseFileNameNoExt, '.jpg']);
% Now save the JPG image.
imwrite(dblSubtractedImage{value1}, fullFileName);
 guidata(hObject, handles);
end

I get the following error message:

Error in

matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)ng('pushbutton4_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback.

Index exceeds the number of array elements (1).

Error in ng>pushbutton4_Callback (line 280)

imwrite(dblSubtractedImage{value1}, fullFileName);

Error in gui_mainfcn (line 95)

feval(varargin{:});

Error in ng (line 42)

gui_mainfcn(gui_State, varargin{:});

Error in

matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)ng('pushbutton4_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback.

Warid Islam 2021-6-14

Hi @Walter Roberson,

I have figured out the solution for the above problem. Thank you very much for your suggestions. It was really helpful.

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Answer 2

ytzhak goussha 2021-6-9

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/852370-unable-to-do-subtraction-of-images-in-gui#answer_721270

I think that the problem is that you are trying to resize an image in a cell array

value1=handles.value1; (this is the index of the image in the cell array i geuss)

orig_imgs1 = handles.InputImage1; (this is a cell array of images)

output_img1=handles.InputImage2; (this is a cell array of images)

handles.dblSubtractedImage = {};

[rowsorig_imgs1 colsorig_imgs1 numberOfColorChannelsorig_imgs1]=size(orig_imgs1);

[rowsoutput_img1 colsoutput_img1 numberOfColorChannelsoutput_img1]=size(output_img1);

if rowsoutput_img1 ~= rowsorig_imgs1 || colsorig_imgs1 ~= colsoutput_img1

output_img1 = imresize(output_img1{value1}, [rowsorig_imgs1 colsorig_imgs1]); (here you must specify which image you want to resize)

end

dblSubtractedImage = (orig_imgs1{value1}) - (output_img1{value1});

imshow(dblSubtractedImage,'parent',handles.axes3);

handles.dblSubtractedImage{end+1}= dblSubtractedImage;

guidata(hObject, handles);

end

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Warid Islam 2021-6-12

Hi Walter,

I tried but no image is being displayed.

Warid Islam 2021-6-12

在 MATLAB Online 中打开

Hi @Walter Roberson,

I managed to solve the issue as I am getting a result in the 3rd image axes.

value1=handles.value1;
InputImage1 = handles.InputImage1{value1};
InputImage2=handles.InputImage2{value1};
InputImage2=imresize(InputImage2,0.5);
handles.dblSubtractedImage = {};
    [rowsInputImage1 colsInputImage1 numberOfColorChannelsInputImage1]=size(InputImage1);
     [rowsInputImage2 colsInputImage2 numberOfColorChannelsInputImage2]=size(InputImage2);
if rowsInputImage2 ~= rowsInputImage1 || colsInputImage1 ~= colsInputImage2
    InputImage2 = imresize(InputImage2(value1), [rowsInputImage1 colsInputImage1]);
end
   dblSubtractedImage = (InputImage1) - (InputImage2);
 
   imshow(dblSubtractedImage,[],'parent',handles.axes3);
   handles.dblSubtractedImage{end+1}= dblSubtractedImage;
   guidata(hObject, handles);
   end
   

However, I think the subtraction has not worked properly, as the result in axes 3 is the same as axes 1. Any suggestions would be appreciated.

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Unable to do subtraction of images in GUI

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Unable to do subtraction of images in GUI

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