I have installed sumatra ver. 3.2 and been using it for few months and all seems well. However some days ago my mom emailed a couple of heic files and sumatra isn’t able to open them. Why is this happening?. Shouldn’t sumatra be able to read these files or what?. There are other convertion tools for this, but I was hoping that sumatra would open this without needing this. Could someone help me here?
SumatraPDF does not read heic files since it was an Apple not Microsoft format
Heic files were not supported on windows until recently and is still not supported on all devices since in effect it needs a codex plug-in, Microsoft call them HEIF ! thus there is a commercial one for MS paint support or else use the MS apps HEIF version. Get HEIF Image Extensions - Microsoft Store en-GB
The format is not fully cross platform nor aimed for PDF documents use so is not to my knowledge in the MuPDF pipeline.
[Later Edit] but SumatraPDF from version 3.4.14180 onwards can use any suitable windows codex that itself views those files, ensure the image is viewable in classic photo viewer first.
I didn’t know that. By the way I forgot to mention that the Windows version I use is Windows 7 Starter. Since the computer which I use is a Toshiba NB505 has limited resources and as of 2021 Windows 7 is no longer supported by Microsoft, the link you provided would not work for me to displaying heic images. I thought Sumatra would support them. Would it happen in the near future? I don’t know. As I mentioned what I can do is to use imagemagick to convert those files into a jpg format, but I just wanted to avoid this additional step. Perhaps do you know something which I could use to preview those files without requiring converting those? and which of course works on Windows 7?.
I too use an underpowered Toshiba Laptop (AMD E1 but crawls along on Windows 10 Pro)
Especially for your Moms benefit 
Check out pre-release 3.4.14180+
see https://github.com/sumatrapdfreader/sumatrapdf/issues/2196
NOTE Windows itself must have the heic/heif support added for SumatraPDF to be able to use it.
For Windows 10 users it may or may not have been installed via Microsoft but there is a free non commercial version for windows 7/8/ and upwards so check out
CopyTrans is the app I installed on Windows 10 to take above screenshot of heic or heif samples viewed in SumatraPDF 3.4.14181
I can confirm the CopyTrans heic support works on an atom netbook running win 7
Note it may on first file.heic opened in SumatraPDF look like its not working, if so open the heic file in Windows photo viewer seems to help trigger first time running the heic support in windows!
