Custom Picture above 15 megabytes to upload simply loads the zone. A help anywhere.

Hello
It is not better to solve uploading pictures?
I have a problem with uploading large images.
This problem happens according to the size of the RAM memory of the computer of the user.
A customer who has only 4 G RAM with Windows 7 loaded image with a maximum size of 12 megabytes
Larger image just recorded. When uploading large files, eg. 20 megabytes console him in Firefox writes (uncaught exception: out of memory)
The problem is that when recording such a large figure nothing happens.
Pops, no information, nothing. Then the customer think that this program does not work and leaves the e-hop away.

Customer 8 G RAM and Windows 8.1 loads eg. 18 megabytes image, but more did not.
Settings:
Maximum Image Size (MB) = 50 MB
Limited to one file is one gigabyte
POST also upload one gigabyte