Today I noticed that some product images on a client’s site were not displaying. This was puzzling because I had recently migrated the site to a new server and had spent quite sometime testing the site.
To cut a long story short, the cause of the problem was two fold. Firstly, the missing images were huge. Resizing one of them solved the problem for that particular product. This led me to the cause of the second problem – the php memory limit on the new sever was 64M. Increasing the memory limit to 258M resulted in all the large images displaying properly.
Ideally I would resize all the large images but that will have to wait for another day.
So, make sure to check your php memory size if you encounter a similar situation of your Magento product images not being displayed.