NC13: Dicom viewer 0.06 does not display anything

Instead of displaying an image Nextcloud wants to download it. Also no information in the sidebar.

File structure of the Dicom file:

Android viewer is working well: does work with my Nextcloud instance. But that file has a .dcm extension and my Dicom files don’t have one.

What is wrong there?
Thank you!


Nextcloud needs to have the file extension to determine which app should be started to view a file. This is pretty much the same like on Windows. I guess if you double click the files on your Laptop/ PC Windows will always ask which program it should use to view them. Nextcloud on the other hand can’t ask that question and therefor only offers the file for download.

Whatever is creating these files, it should be configured to add a file extension.
Just for testing, you could rename one of your files, add .dcm to the file name and check if the file opens now in the app.

I’ve got some CDs of different medical institutes and all of them have the mentioned file structure.

But nonetheless renaming to .dcm is working, as well as with Irfanview in Windows 10.

One medical examination contains about 70-80 single files, all of them without an extension. So, im my humble opinion, the viewer should open them without a file extension, as the Android viewer can do.

But anyway, thank you for the tip with renaming to .dcm.


Unfortunately that’s not that easy. And both NC and the andoid app are approaching the files differently.
On Android you start the app and then let the app open the files. In this case the app has no other possibility to try to render these files as DCM files, because the app can’t do more than that.

Nextcloud in the other hand is like Android (not like the android app!), Unix, Windows, … When you click the file and expect the system to open the file with the correct program/ app, all these systems need a hint - some information - what type of file that could actually be, so that the right program/ app can be chosen.
Clicking that file in Windows or Android (in the android file explorer) it will always ask you which app the systems shall start to open the file with.
Concludingly, it is quite a bad way to store files without a file extension. While we probably can’t do anything about the way the files are stored (if you can please ask the responsible people to use .dcm as file extension :wink: ), we can only rename the files.

Making this task easier for you, both Unix and Windows can do that pretty easy.
On Windows for example, just open the CMD (press WIN + R -> type “cmd” and hit enter), navigate to the path with your dcm files (without the file extension) and run:
ren * *.dcm

You could also write this command into a bat file and copy the bat file into all folders with these files without file extension and execute that bat file.

Thanks @Schmu, i have already renamed the files and everything seems to work well now, except of sliding through a sequence of images and the preview.

Obviously the medical institutes are shipping the Dicom files on CD without a file extension, so i would suggest to binary open them first before proceeding, like Apple can do.

This is a screenshot of a Dicom image in a hex editor:


But you are right, a file extension is mandatory for Windows. Now i can even open the Dicom images with Irfanview with a simple double click on the file.


Hi @Sanook

Scrolling through series is implemented in the recent version 1.0.0, could you give it a try?


1 Like

Hi @ayselafsar
Not working or i couldn’t find out how to scroll through the images.

Screenshot of 1.0.0 of the mentioned image above:

Hi @Sanook,

It looks like it is a single image, could you try to open a folder by selecting ‘Open with DICOM Viewer’ action on context menu?

Nice! It works!
I did not come up with the idea to open the folder with the Dicom viewer.