Nginx HttpImageFilterModule with watermark support

Usage:

image_filter watermark /path/to/watermark.png [ bottom-right (default) | top-left | top-right | bottom-left | center ];

See also http://nginx.org/en/docs/http/ngx_http_image_filter_module.html#image_filter

nginx-watermark.patch

For using in spec directly

...
%define with_watermark 1
...
%if 0%{?with_watermark}
# PATCH for watermarks
Patch7:         nginx-watermark.patch
%endif
...

Tested with nginx 1.9.12