So I'm running an anime site with K2 and I have placeholder images saying "coming-soon" when the screenshot has not been uploaded yet. I thought why not share my code for that.
It's actually really easy.
First you need to open up the item.php model which can be found in /components/com_k2/models/item.php
Scroll down to line 118 and you'll see a block of code with a bunch of "if" statements. Select that block (from 118 to 159 (right before it says //extra fields) and delete it.
Replace that with this code found here:
pastebin.com/SzGWTbfX
Now all you need to do is change the "coming-soon" part to whatever you want. The images should be stored in the /images/ folder in the joomla root.
In my case i just have a small version and a large version. I don't need any other sizes. You can obviously change that ;)
Question? Ask!