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Unable to do subtraction of images in GUI

4 vues (au cours des 30 derniers jours)
Warid Islam
Warid Islam le 9 Juin 2021
Commenté : Warid Islam le 14 Juin 2021
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.

Réponse acceptée

Image Analyst
Image Analyst le 12 Juin 2021
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);
  12 commentaires
Warid Islam
Warid Islam le 14 Juin 2021
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
Warid Islam le 14 Juin 2021
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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Plus de réponses (1)

ytzhak goussha
ytzhak goussha le 9 Juin 2021
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
  7 commentaires
Warid Islam
Warid Islam le 12 Juin 2021
Hi Walter,
I tried but no image is being displayed.
Warid Islam
Warid Islam le 12 Juin 2021
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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