Uploading a large image attachment using SMF fails.

If you receive a white screen when uploading a large image attachment using SMF then to fix follow the below steps :

1) download the file Sources/Subs-Graphics.php from your hosting account

2) edit the file using notepad, and locate the line (around line 326 in the file )

@ini_set('memory_limit', '90M');

and change this to 

@ini_set('memory_limit', '255M');

then save the file in notepad, and upload the file using FTP replacing the existing file.