I have a number of plugins in the WordPress plugin directory. There is an issue with screenshots that I have been trying to figure out for a while. In fact, I have experienced the same issue with some other plugins.
You may have noticed a download prompt when clicking on a screenshot.
This is a little annoying for users who are trying to view an image. Turns out it is actually caused by incorrect MIME Type.
Editing MIME Type Using TortoiseSVN
If you use TortoiseSVN (on windows) to commit to WordPress plugin directory please follow these steps to set the MIME Type of an image correctly.
1) Right Click on the screenshot and select TortoiseSVN -> Properties.
2) As you can see that the svn:mime-type property is set to application/octet-stream. Go to Edit -> Advanced to modify it.
3) Enter the correct MIME Type. It should be set to –
a) image/jpg for a jpeg file
b) image/png for a png file
Do it for all the screenshots (if you have more than one). Click Ok to update the value.
Now commit changes to the repository and you shouldn’t see the download prompt anymore.
Did this tweak work for you? Feel free to share your thoughts in the comments.