Mastering NGINX - Second Edition

Generating images

Instead of writing an image manipulation module for your application, you can configure NGINX to handle some simple transformations. If your image-manipulation needs are as simple as rotating an image, resizing it, or cropping it, NGINX is capable of doing this for you.

To make use of this functionality, you need to have installed the libgd library, and enabled the image_filter module at compile time (--with-http_image_filter_module). If that is the case, you now have use of the directives in the following table:

Image filter directives	Explanation
empty_gif	This directive causes a 1x1 pixel transparent GIF to be emitted for that location directive.
image_filter	This directive transforms an image, according to one of ...