My web host recently had me recompile Apache in attempt to fix an issue on my server. Ever since, my thumbnail generation script returns this error:
Fatal error: Call to undefined function imagecreatetruecolor()
Do I need to reactivate/reinstall GD? If so, how do I do this?
httpd.conf is the file you need to edit but because your using CentOS which is a Unix system you will need to run the sudo command as only the windows server comes with GD library pre-installed
The default httpd.conf location on CentOS is /etc/httpd/httpd.conf
Use an editor like vim or nano to adjust the config file as suggested by SgtLegend.
I am not very familiar with Linux or server maintenance. I am running on a CentOS server. Which httpd file would typically be the one I should edit?
In your Apache httpd file find
and simply remove the ; before it. If your on a UNIX system read this http://www.cyberciti.biz/faq/ubuntu-linux-install-or-add-php-gd-support-to-apache/