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ngx_small_light

by cubicdaiya

cubicdaiya /ngx_small_light

Dynamic Image Transformation Module For nginx.

438 Stars 71 Forks Last release: over 3 years ago (v0.9.2) Other 318 Commits 51 Releases

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ngxsmalllight

A dynamic image transformation module for nginx.

Table of contents

Features

Supports the various image-processings below.

  • Resize
  • Rotate
  • Sharpen
  • Unsharpen
  • Blur
  • Border
  • Canvas
  • Crop
  • Composition
  • JPEG Hinting(except GD)
  • Format convert(e.g. PNG -> JPEG)
  • Color-space convert(e.g. CMYK -> sRGB)

ngx_small_light
is developed for using as the same way as modsmalllight as possible in nginx.

Supported Formats

Supports the formats below.

  • JPEG
  • GIF(except Imlib2)
  • PNG
  • WebP(except Imlib2)

Dependencies

Installation

cd ${ngx_small_light_src_dir}
./setup
cd {$nginx_src_dir}
./configure --add-module=${ngx_small_light_src_dir}
make
make install

If you want to enable the libraries except ImageMagick in 

ngx_small_light
, add the options below when executing 
setup
. (ImageMagick is always enabled) 
./setup                         # enable ImageMagick
./setup --with-imlib2           # enable ImageMagick and Imlib2
./setup --with-gd               # enable ImageMagick and GD
./setup --with-imlib2 --with-gd # enable ImageMagick and Imlib2 and GD

Dynamic module

You can also compile 

ngx_small_light
as the dynamic module with 
--add-dynamic-module
in nginx-1.9.11 and ngxsmalllight-0.6.15 or later. 
cd ${ngx_small_light_src_dir}
./setup
cd {$nginx_src_dir}
./configure \
--modules-path=/usr/local/nginx/modules \
--add-dynamic-module=${ngx_small_light_src_dir}
make
make install

Add the configuration below for loading module dynamically.

load_module /usr/local/nginx/modules/ngx_http_small_light_module.so;

Getting started

Add the configuration below to some server context in nginx.conf and start nginx.

small_light on;
location ~ small_light[^/]*/(.+)$ {
    set $file $1;
    rewrite ^ /$file;
}

If you can get the original image of image.jpg from the URL below,

http://$host:$port/img/image.jpg

You will be able to get the converted image of image.jpg from the URL below.

http://$host:$port/small_light(dw=300,dh=300)/img/image.jpg

The part of 

small_light(...)
is called small_light function.

Configuration example

There is some configuration example below.

server {
    listen 8000;
    server_name localhost;


small_light on;
small_light_pattern_define msize dw=500,dh=500,da=l,q=95,e=imagemagick,jpeghint=y;
small_light_pattern_define ssize dw=120,dh=120,da=l,q=95,e=imlib2,jpeghint=y;

# http://localhost:8000/small_light(p=msize)/img/filename.jpg -> generate msize image
# http://localhost:8000/small_light(p=ssize)/img/filename.jpg -> generate ssize image
# http://localhost:8000/small_light(of=gif,q=100)/img/filename.jpg -> generate gif image which quality is 100
location ~ small_light[^/]*/(.+)$ {
    set $file $1;
    rewrite ^ /$file;
}


}

Directives

small_light

|Syntax |small_light on | off| |-----------|---------------------------| |Default|off | |Context|server, location |

This directive sets whether image-processing with 

ngx_small_light
is enabled in a server context.

smalllightgetparam_mode

|Syntax |smalllightgetparam_mode on | off| |-----------|-----------------------------------------| |Default|off | |Context|server, location |

This directive sets whether converting-image is enabled by GET parameters instead of small_light function (e.g. 

/small_light(dw=200,dh=200)
). At the expense of it, a small_light function is disabled. But you need to set both 
small_light
and 
small_light_getparam_mode
on to enable the feature of this directive.

smalllightmaterial_dir

|Syntax |smalllightmaterial_dir path| |-----------|---------------------------------------------| |Default| | |Context|server |

This directive assigns the directory for embedded icon images.

smalllightpattern_define

|Syntax |smalllightpatterndefine patternname parameters| |-----------|----------------------------------------------------| |Default| | |Context|server |

This directive names comma-delimited parameters.

smalllightradius_max

|Syntax |smalllightradius_max number| |-----------|-------------------------------| |Default|10 | |Context|server,location |

This directive sets maximum radius value of geometry for 

sharpen
and 
unsharp
and 
blur
.

smalllightsigma_max

|Syntax |smalllightsigma_max number| |-----------|-------------------------------| |Default|10 | |Context|server,location |

This directive sets maximum sigma value of geometry for 

sharpen
and 
unsharp
and 
blur
.

smalllightimlib2tempdir

|Syntax |smalllightimlib2tempdir path [level1 [level2 [level 3 ]]]| |-----------|---------------------------------------------------------------------| |Default|smalllightimlib2_temp 1 2 | |Context|server |

This directive assigns the directory for temporary file for Imlib2 processing. This directive is available when Imlib2 is enabled.

smalllightbuffer

|Syntax |smalllighbuffer size| |-----------|------------------------| |Default|1m | |Context|server |

This directive assigns the maximum size of the buffer used for reading images when Content-Length is not set in response headers.

Parameters for small_light function

|Parameter |Type |Default |Description |ImageMagick|Imlib2|GD | |-----------|------|-----------|------------------------------------------------|-----------|------|---| |p |string| |named pattern of comma-delimited parameters | :o:| :o:|:o:| |e |string|imagemagick|engine name (imagemagick, imlib2, gd) | | | | |q |number| |quality | :o:| :o:|:o:| |of |string| |output format (jpg, gif, png, webp) | :o:| :o:|:o:| |jpeghint |char |n |enable jpeg hinting (y, n) | :o:| :o:|:x:| |dw |coord |sw |destination width | :o:| :o:|:o:| |dh |coord |sh |destination height | :o:| :o:|:o:| |dx |coord |sx |destination x coordinate | :o:| :o:|:o:| |dy |coord |sy |destination y coordinate | :o:| :o:|:o:| |da |char |l |destination aspect ratio contol (l, s, n) | :o:| :o:|:o:| |ds |char |n |destination scaling control (s, n) | :o:| :o:|:o:| |cw |number| |canvas width | :o:| :o:|:o:| |ch |number| |canvas height | :o:| :o:|:o:| |cc |color |000000 |canvas color | :o:| :o:|:o:| |bw |number| |border width | :o:| :o:|:o:| |bh |number| |border height | :o:| :o:|:o:| |bc |color |000000 |border color | :o:| :o:|:o:| |sw |coord | |source witdh | :o:| :o:|:o:| |sh |coord | |source height | :o:| :o:|:o:| |sx |coord | |source x coordinate | :o:| :o:|:o:| |sy |coord | |source y coordinate | :o:| :o:|:o:| |pt |char |n |pass through control (y, n) | :o:| :o:|:o:| |sharpen |string| |radius,sigma (e.g. 10x5) | :o:| :o:|:o:| |unsharp |string| |radius,sigma,amount,threshold (e.g 2x5+0.5+0) | :o:| :x:|:x:| |blur |string| |radius,sigma (e.g. 5x10) | :o:| :o:|:x:| |embedicon |string| |embedded icon file in 

small_light_material_dir
| :o:| :x:|:x:| |ix |number|0 |embedded icon x coordinate | :o:| :x:|:x:| |iy |number|0 |embedded icon y coordinate | :o:| :x:|:x:| |angle |number|0 |angle of rotation (90, 180, 270) | :o:| :o:|:o:| |progressive|char |n |make JPEG progressive (y, n) | :o:| :x:|:x:| |cmyk2rgb |char |n |convert colorspace from CMYK to sRGB (y, n) | :o:| :x:|:x:| |rmprof |char |n |remove profile (y, n) | :o:| :x:|:x:| |autoorient |char |n |enable adjust image orientation automatically (y, n) | :o:| :x:|:x:|

The values of 

da
are 
l
and 
s
and 
n
. These present the meanings below. 
  • l
    : long-edge based
  • s
    : short-edge based
  • n
    : nope

There are any limitations below.

  • of=gif
    and 
    of=webp
    are not supported when 
    e=imlib2
    .
  • autoorient
    is available ImageMagick-6.9.0 or later.
  • The value of 
    radius,sigma
    for 
    sharpen
    and 
    unsharp
    and 
    blur
    is limited by 
    small_light_radius_max
    and 
    small_light_sigma_max
    .

There are the types of each parameter below.

|Type |Description | |------|-------------------------------------------------| |coord |coordicante or pixel. percent when appending 'p' | |char |character | |number|integer number | |color |rrggbb or rrggbbaa | |string|string |

Named Pattern

ngx_small_light
supports to name comma-delimited parameters with the 
small_light_define_patern
. 
small_light_pattern_define small dw=120,dh=120,q=80,e=imagemagick,jpeghint=y;

If the line above is added to some server context in nginx.conf, the two URLs below return same response.

  • http://$host:$port/small_light(p=small)/img/image.jpg
  • http://$host:$port/small_light(dw=120,dh=120,q=80,e=imagemagick,jpeghint=y)/img/image.jpg

Using GET parameters

ngx_small_light
supports to convert image not only by small_light function but by GET paramenters in 
v0.5.0
or later. You need to set both 
small_light
and 
small_light_getparam_mode
on to enable this feature. At the expense of enabling this feature, small_light function (e.g. 
/small_light(dw=300,dh=300)/img.jpg
is disabled. 
small_light on;
small_light_getparam_mode on;

In the configuration above, the url below does not return converted image.

http://localhost:8000/small_light(dw=200,dh=200)/img/image.jpg

Instead the url below returns converted image expected by right.

http://localhost:8000/img/image.jpg?dw=200&dh=200

Enabling WebP Transformation

ngx_small_light
supports WebP transformation with ImageMagick and GD. Given 
of=webp
to small_light function, 
ngx_small_light
transforms image format into WebP. But ImageMagick requires libwebp and GD requires libvpx. You need to embed these libraries in building ImageMagick and GD for enabling WebP transformation.

If WebP transformation is not available, 

nginx
outputs the line like below in error.log in processing image with 
of=webp
. 
WebP is not supported

If WebP transformation with ImageMagick is available, the output of 

convert -list format
includes the line like below. 
$ convert -list format | grep -i webp
     WEBP* WEBP      rw-   WebP Image Format (libwebp 0.5.0[0208])

If WebP transformation with GD is available, the output of 

gdlib-config --libs
includes 
-lvpx
.

In general, the packages of ImageMagick and GD provided from the linux distributions such as Ubuntu and CentOS does not embed the library for WebP transformation by default. In such cases, you need to build ImageMagick or GD yourself.

Optimizing Tips

There are some optimizing tips for 

ngx_small_light
.

JPEG hinting

When the output format is JPEG and image-converting engine is ImageMagick or Imlib2, you may give 

jpeghint=y
. The speed of processing images is improved dramatically.

Limit thread-number with OpenMP

When image-converting engine is ImageMagick and the version of 

ngx_small_light
is lower than 
v0.6.14
, giving 1 to 
OMP_NUM_THREADS
or 
MAGICK_THREAD_LIMIT
in 
nginx.conf
is recommended strongly. Because OpenMP is enabled in ImageMagick by default and ImageMagick enabled OpenMP is very slow on multi-process environment. 
env OMP_NUM_THREADS=1; # or env MAGICK_THREAD_LIMIT=1;

Or you can avoid this problem by building ImageMagick with 

--disable-openmp
.

In 

v0.6.14
or later, they are no longer required. Because 
ngx_small_light
always sets the thread-number with OpenMP 1.

Limitations

ngx_small_light
has the limitations below.

Not supported features with Imlib2

The transformation with Imlib2 does not support to write GIF-image. Because Imlib2 has the function for loading GIF-image but does not have the function for saving. Additionally, the transformation by Imlib2 does not support to write and read WebP-image. So 

of=gif
and 
e=imlib2
are not enabled to specify at once. If these are specified, 
ngx_small_light
returns 415(Unsupported Media Type).

Not supported features with GD

The transformation with GD supports to write WebP-image. But it is the experimental feature.

Not supported animated GIF

ngx_small_light
does not support the transformation kept animation for animated GIF. Because it takes long time to transform(e.g. resize, crop) animated GIF kept animation. So it is not realistic for 
ngx_small_light
to support an animated GIF.

If the animated GIF is given, 

ngx_small_light
transforms only the first frame.

Running Tests

perl Build.PL
cpanm --installdeps .
NGINX_BIN=${nginx_prefix_dir}/sbin/nginx ./Build test
# or
NGINX_BIN=${nginx_prefix_dir}/sbin/nginx prove t/**/*.t

License

Please read the COPYING.

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