When a user upload a resized picture, phpbb use original filesize (exif data) and not real size of picture.
phpbb3.2.1 with upload file restrictions set up as :
max size : 1024 x 1024 pixels
max file size : 1 Mb
Several users claims since 3.2.1 update they can not post pictures altought they are conform.
File example : http://www.greffer.net/images/uploads/test.jpg
Size 465x830 pix, 280 ko
When I upload with my admin account, no error.
But, if I upload as simple user privilege, at the end of file upload, a error appears, saying that maximum size is 1024x1024 but the file uploaded is : 3920 x 2204.
I test this file with a php test file with getimagesize function , itreturns :
Array (  => 465  => 830  => 2  => width="465" height="830" [bits] => 8 [channels] => 3 [mime] => image/jpeg )
The file image dimensions seems perfect.
On french phpbb help forums, some others users have the same problem.
It seems, if this data is available, that phpbb use EXIF image size and not picture real size (the original picture has been resized by the user, EXIT data contains original size, not size after resizing).
Exif data of this picture :
Image size and exif resolution are not egal.
When I erase exif data exiv2 software, the upload is not OK.