The behaviour of these functions is affected by settings in php.ini.
|gd.jpeg_ignore_warning||"1"||PHP_INI_ALL||Available since PHP 5.1.3.|
Here's a short explanation of the configuration directives.
|7.1.0||The default of gd.jpeg_ignore_warning has been changed from 0 to 1.|
See also the exif configuration directives.
Image functions are very memory intensive. Be sure to set memory_limit high enough.