FAQ - Cannot create thumbnails
Cannot create thumbnails
Creating thumbnail images (i.e. small versions) requires three things.
You can check these using information from the “Server information” section of the control panel.
Firstly, your server need to have a PHP graphics extension.
webtrees can use either
gd, your server information should include a section
gd, with an entry
ImageMagickyour server information should include a section
Imagick, with an entry
ImageMagick supported formatsthat includes both
Secondly, you need sufficient memory. To process an image, GD requires 4 bytes-per-pixel and Imagick requires 10 bytes-per-pixel. An image that is 5000×4000 pixels will require 5000×4000×4 = 80MB (GD) or 5000×4000×10 = 200MB (Imagick). The rest of the script requires approximately 20MB.
So generating a thumbnail of a 5000×4000 pixel image will require 100MB (GD) or 220MB (Imagick).
memory_limit must be higher than this.
Thirdly, you need to have sufficient CPU power/time.
Image manipulation requires a lot of server resources.
It has been observed that
gd can be 30 times slower than
For this reason,
ImageMagick is recommended.
However, if you have very large images, and low memory limits, then you will need to use