Haunted Code (Serious)

I know this might sound like a joke but I promise I am being completely serious. I want to preface this question by saying that I don't need help fixing this code, I've rewritten it and it works fine now. I am simply looking to see if anyone knows why this is happening or if it has happened to anyone else

I've been trying to create a GUI where I can click a button, use it to select an image, and then display that image on an axes. All was going well but when I went to test the code (as follows), the image loaded with a small blue square in the corner. Looking closer at that box, I found that there is an image of what appears to be a young boy smiling (3 images attached below show him appearing on 2 different images and then one zoomed in on him). He appears on every image I've tried, in various sizes. I am 99% certain this is not an image from my local storage; my device is brand new and I cannot fathom as to why I would have such an image saved somewhere.

% --- Executes on button press in LoadButton.
function LoadButton_Callback(hObject, eventdata, handles)
% hObject    handle to LoadButton (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
[filename, path]=uigetfile('*.jpg','Select an Image')
fullfilename=fullfile(path,filename)
Image= imread(fullfilename);
image(Image,'Parent',handles.Image);
set(handles.Image,'visible');
imshow(image);

If anyone has any idea what's going on please let me know.

[Duijnhouwer]

the functin "image" wihout arguments shows that boy by default (yes, it's ridiculous)

The below code shows something similar to yours

you don't need the imshow(image) call

or at least call imshow(Image)

(better not distinguish names on capitalization alone)

clf
M1=imread('peppers.png'); % comes with matlab
image(M1); 
hold on 

imshow(image) % first displays the default image and then throws an error (wrong input for imshow)

[Judy Yang]

Oh thanks for the info about the image. I already rewrote the code entirely though so don't worry about troubleshooting. Was just confused on where the image was from.

[Stephen23]

That is the default image. See:

https://blogs.mathworks.com/steve/2006/10/17/the-story-behind-the-matlab-default-image/

It gets shown in your axes because of this superfluous line of code:

imshow(image);

where you call image without an input argument, hence it shows the default image. Solution: get rid of that line.

Answer 1

[Tommy]

That is the default image upside down. You can view it by calling just

>> image

When you call

imshow(image);

MATLAB first evaluates image and shows the default image in the current axes. I believe it then tries to call imshow() on the output of image, which is an Image object, and so it should throw an error (it does for me). You will see the blue kid in the corner (and the error) with the following three lines:

Image = imread('pears.png');
image(Image);
imshow(image);

The image is actually first being plotted with the call to image() - you don't need the third line.

I'm assuming handles.Image is supposed to be the axes where you are plotting your image. How about this instead?

Image = imread(fullfilename);
image(handles.Image, Image); % or, imshow(Image, 'Parent', ax); if you'd like

(edit) And it's not just a boy :)

[Judy Yang]

That easter egg post was very interesting, thank you! I realized a lot of the other stuff you've mentioned and already fixed the code so you don't need to worry about helping me troubleshoot but thank you for that too.

[Ed]

I have also discovered that

str2num('image not found')

also displays this default image. This was quite a surprise, especially as 'image not found' was an unexpected string found in a large dataset which should only have been numbers.

[Steven Lord]

Correct. This is because, as the documentation page for the str2num function states, "str2num is implemented using eval which might lead to undesired side effects."

[Walter Roberson]

Consider using the new Restricted evaluation mode of str2num

[Stephen23]

Consider STR2DOUBLE or SSCANF or any other conversion function that does not rely on EVAL.