How can I get image file in web app?

Hi, I am using R2021a version, and I made a web app that gets image file as input, and shows image processing result for that image.

When I tried to run the app right away in app designer, it worked well.

However, when I made it as web app, and ran in localhost, I found an error message saying format of image taken by uigetfile is not supported.

Above is my code, and below is an error message and error cause shown by try catch statement. The last sentece is saying like 'Cannot configure file format'.

And this is value of app.target_img_addr :

It seems uigetfile reads the file from the client pc, and saves it in server session, and then imread reads that file from the server pc itself.

And apparently, when I took a look at the above address, I could not read the test.png in server session.

This means that uigetfile didn't save the file perfectly, and thus imread cannot read the file.

So, is matlab web app server not supporting uigetfile? or did I do something wrong?

If it is the former case, what is an alternative way to get image file from user?

Answer 1

[Jan]

You are not the only person with this problem. See: https://www.mathworks.com/matlabcentral/answers/884084-problems-with-uigetfile-and-imread-in-simple-matlab-web-app

I assume, this is a bug of R2021a. Please contact the official support of MathWorks to ask for a solution.

[Kyoungseo Kim]

Oh, you're right. That man in the given page is suffering a same problem with me, literally. Thank you.

However, when I wrote and ran a same code at April or May this year, it worked even for web app...

Maybe Mathworks updated something wrong... XD

[Jan]

Yes, I think this is a bug in an update. Do you know how to report a bug?

[Kyoungseo Kim]

Oh.. I don't know. Actually, I was going to start from calling mathworks branch in our country, which is mathworks korea, and just trying r2020b version for a while.

However, if you can teach me how to report (I'm a newb in matlab...), it will be really helpful for me!

[Jan]

Start at: https://www.mathworks.com/support/contact_us.html?s_tid=hp_ff_s_support

Press "report a bug". You can insert a link to your question here also.

[Kyoungseo Kim]

Thank you!