Latest revision as of 19:45, 2 May 2012

[edit] Synopsis

Version: 0.7.54+

This module is a filter for transforming JPEG, GIF and PNG images. It is not enabled by default to enable it, provide this option to ./configure when building nginx:

--with-http_image_filter_module

libgd is required to build and run the module. We recommend using the latest version of libgd.

[edit] Example Configuration

location /img/ {
    proxy_pass     http://backend;
    image_filter   resize  150 100;
    error_page     415   = /empty;
}
 
location = /empty {
    empty_gif;
}

[edit] Directives

[edit] image_filter

Syntax:	image_filter `off` image_filter `test` image_filter `size` image_filter `rotate` `90` \| `180` \| `270` image_filter `resize` width height image_filter `crop` width height
Default:	off
Context:	location
Reference:	image_filter

Specifies the type of transformation to apply to the image, one of the below:

test: checking that the response is indeed an image format JPEG, GIF or PNG. Otherwise, an error 415.

size: Gives information about the image in JSON format. For example,

{ "img" : { "width": 100, "height": 100, "type": "gif" } }

Or if an error occurs,

{}

resize: proportionally reduces the image to a specified size.

crop: proportionally reduces the image to a specified size and trims extra edge.

[edit] image_filter_buffer

Syntax:	image_filter_buffer size
Default:	1M
Context:	http server location
Reference:	image_filter_buffer

Sets the maximum size for reading the image.

[edit] image_filter_jpeg_quality

Syntax:	image_filter_jpeg_quality quality
Default:	75
Context:	http server location
Reference:	image_filter_jpeg_quality

Sets the rate of loss of information when processing the images as JPEG. The maximum recommended value is 95.

[edit] image_filter_sharpen

Syntax:	image_filter_sharpen percent
Default:	0
Context:	http server location
Reference:	image_filter_sharpen

[edit] image_filter_transparency

Syntax:	image_filter_transparency `on` \| `off`
Default:	on
Context:	http server location
Reference:	image_filter_transparency

This directive allows you to disable image transparency in GIF and palette-based PNG to improve image resampling quality.

True color PNG alpha-channels are always preserved despite this setting.

Note: Grayscale PNG's are untested, but should be handled as truecolor PNGs.

[edit] References

Original Documentation

@@ Line 27: / Line 27: @@
 == image_filter ==
+<include wikitext nopre src="http://wiki.nginx.org/nginx.org/http/ngx_http_image_filter_module/image_filter.txt" />
-'''Syntax:''' ''image_filter (test|size|resize width height|crop width height)''
-'''Default:''' ''none''
-'''Context:''' ''location''
 Specifies the type of transformation to apply to the image, one of the below:
@@ Line 47: / Line 42: @@
 * crop: proportionally reduces the image to a specified size and trims extra edge.
 == image_filter_buffer ==
-'''Syntax:''' ''image_filter_buffer size''
+<include wikitext nopre src="http://wiki.nginx.org/nginx.org/http/ngx_http_image_filter_module/image_filter_buffer.txt" />
-'''Default:''' ''1M''
-'''Context:''' ''http, server, location''
 Sets the maximum size for reading the image.
 == image_filter_jpeg_quality ==
-'''Syntax:''' ''image_filter_jpeg_quality [0...100]''
+<include wikitext nopre src="http://wiki.nginx.org/nginx.org/http/ngx_http_image_filter_module/image_filter_jpeg_quality.txt" />
-'''Default:''' ''75''
+Sets the rate of loss of information when processing the images as '''JPEG'''. The maximum recommended value is '''95'''.
-'''Context:''' ''http, server, location''
+== image_filter_sharpen ==
+<include wikitext nopre src="http://wiki.nginx.org/nginx.org/http/ngx_http_image_filter_module/image_filter_sharpen.txt" />
-Sets the rate of loss of information when processing the images as '''JPEG'''. The maximum recommended value is '''95'''.
 == image_filter_transparency ==
-'''Syntax:''' ''image_filter_transparency on|off''
+<include wikitext nopre src="http://wiki.nginx.org/nginx.org/http/ngx_http_image_filter_module/image_filter_transparency.txt" />
-'''Default:''' ''on''
-'''Context:''' ''http, server, location''
 This directive allows you to disable image transparency in GIF and
@@ Line 81: / Line 67: @@
 = References =
-[http://sysoev.ru/nginx/docs/http/ngx_http_image_filter_module.html Original Documentation]
+[http://nginx.org/en/docs/http/ngx_http_image_filter_module.html Original Documentation]

HttpImageFilterModule