Fatal error: Out of memory

I’m not sure where you’re getting those stats, but I doubt that is showing you the amount of memory being used while processing the images. If you navigate to some memory use screen, you’re seeing the amount of memory currently allocated, which is now an entirely different process from when you were uploading images. The fact that Out of memory (allocated 29884416) is already larger than 27.75 MByte points to this.