ImagePlugin

Image and thumbnail services to display and alignment images using an easy syntax

Use this plugin to control the display and alignment of images using an easy syntax and support for server-side resizing and thumbnailing. There are a set of pre-defined layout formats for images as well as a free layout configurability.

Short example:

You type:

%IMAGE{
  "Westminstpalace.jpg"
  type="frame" 
  align="none" 
  caption="caption text"
}%

You get:

If installed:

Images to be displayed can be located

• at the topic as specified,
• at the location specified in the IMAGEALBUM preference variable,
• at the current topic or
• at a remote URL.

If you specify a remote url using http://... the image is downloaded (using CPAN:LWP::Simple) into a local cache and then processed as usual. WARNING: please be aware of any copyrights of the images you mirror this way.

The topic and IMAGEALBUM parameters can be of the for [<web>.]<topic> . For example putting

   * Set IMAGEALBUM = %SYSTEMWEB%.ImagePlugin

into the current topic will search all images at the given topic.

Syntax

%IMAGE{"foo.gif" ...}%

There are four predefined format types (plain, simple, link, thumbnail, frame, float) that can be used by setting the type paramenter (see below). In addition there is a free-form format parameter to specify any other possible html layout. The Wikipedia format is also supported. See Wikipedia:Wikipedia:Extended_image_syntax.

%IMAGE{"clear"}% will create a proper clear for floats elements.

Arguments

The image name is mandatory. Further arguments are optional.

Name	Values	Default
align	left|center|right|none	none
alt	alt text	image filename
caption	caption text	empty
class	(see html specs)	imageFrame, imageFloat, imageResponsive, … depending on the type
crop	on/northwest/north/northeast/west/center/east/southwest/south/southeast/off: scrop the image to fit the image into the given aspect ratio; other values than on/off specify the area the croped image gravitates to relative to the original (on=center)	off
data_<key;	html5 data added to the image	empty
desc	description text	title text
footer	text to be appended to the html output	empty
format	image layout format string	set by type argument
frame	extract a specific frame or layer from the source file; this comes in handy when rendering a thumbnail for a video clip
layer	alias for frame
lazyload	boolean switch to enable/disable loading images lazy (if supported by the browser)	off
header	text to be prepended to the html output	empty
height	integer value	image width
output	image format to convert the input source to	same as source image, except tiff and svg being converted to png
href	hyperlink when clicking on the image	url of the source image
id	(see html specs)	empty
mousein	javascript executed if moving the mouse over the image	empty
mouseout	javascript executed if moving the mouse off the image	empty
refresh	on/off/img to trigger recomputing images	off
rotate	rotate image by the given dregrees	keep original orientation
size	geometry specification	image geometry
style	(see html specs)	empty
title	title text	alt value
tooltipheight	height of tooltip image	300
tooltip	on/off renders an image preview in a tooltip	off
tooltipcrop	on/northwest/north/northeast/west/center/east/southwest/south/southeast/off: same as crop but used for the tooltip
tooltipwidth	width of tooltip image	300
topic	valid topic name	topic part of IMGALBUM value or current topic
transparent	color to be converted to transparent
quality	compression level for JPEG/MIFF/PNG images
type	simple, plain, link, thumb[nail], frame, float or src	plain
warn	on/off, surpress error warnings	on
web	valid web name	web part of IMGALBUM value or current topic
width	integer value	image width
zoom	on/off to scale images, if set to "on" scaling up images is allowed, otherwise it downscales only	off
filter	one or more image filters to be applied to the image; see below

Image geometry

The image geometry in the size parameter can be specified in a format <width>[px][x<height>[px]], that is width and height can be given as integers with an optional px, where the height is optional, separated with a 'x' in between. Note, that the given width and height values are the maximum width and maximum height that the image will have keeping its aspect ratio. If you want to deform it to an exact measure use the width and height arguments.

Note, that you must set zoom="on" to scale images up. Otherwise images smaller than the given geometry will stay as they are. For instance, when generating thumbnails it is preferable to keep small icons as they are instead of bloating them up to a standard thumbnail size.

Image Filters

ImagePlugin comes with a set of low-level and high-level filters that might be applied to an image. High-level filters are a combination of a set of low-level filters to immitate instagram-like modifications to the image.

Low-level fiters

• autogamma()
• autolevel()
• background(color)
• blueshift(factor)
• blur(radius, sigma)
• brightness(value)
• charcoal(radius, sigma)
• colorize(fill, blend)
• contrast(geometry)
• emboss(radius, sigma)
• equalize(channel)
• gamma(value)
• grayscale(factor)
• hue(value)
• level(level, level, …)
• levelcolors(color1, color2, invert)
• negate()
• noise(value, attentuate)
• normalize(channel)
• oilpaint(radius)
• posterize(levels)
• saturate(value)
• sharpen(radius, sigma)
• tint(fill)

For a more thorough explanation of these filters, please read the color modifications manual of ImageMagick used underneath.

High-level filters

• sepia(factor)
• vignette(factor, color)
• 1977(factor)
• gotham(factor)
• inkwell(factor)
• kelvin(factor)
• moon(factor)
• lomo(factor)
• nashville(factor)
• toast(factor)
• hudson(factor)

Example filters

• autogamma
• gamma(1)
• gamma(2)
• gamma(5)
• gamma(0.8,1.3,1.0)
• grayscale(33%)
• contrast(3)
• grayscale;contrast(3);tint(blue)
• sepia(33%)
• sepia,hue(33.3)
• contrast(3);saturate(160);sepia(60%)
• brightness(50)
• hue(33.3)
• level(25%)
• level(0,75%)
• level(25%,100%)
• level(-25%)
• level(0%,100%,0.5)
• level(0%,100%,2.0)
• levelcolors(green,gold)
• levelcolors(,DodgerBlue)
• levelcolors(Firebrick)
• levelcolors(DarkGreen);autogamma
• levelcolors(navy,lemonchiffon)
• levelcolors(#664B19,#FFFACD);autogamma
• normalize(Yellow)
• noise(Uniform)
• noise(Gaussian)
• noise(Multiplicative)
• noise(Impulse)
• noise(Laplacian)
• noise(Poisson)
• blueshift(0)
• blueshift(0.5)
• blueshift(1)
• blueshift(1.5)
• blur(1,1)
• sharpen(0.4)
• charcoal(,1)
• emboss(1,2)
• vignette(1.5)
• colorize(,50%)
• colorize(blue,10%)
• 1977(33%)
• moon(100%)
• moon(100%);levelcolors(navy,lightyellow)
• toaster(100%)

Format specification

Format strings given in header, footer and format may contain the following pseudo variables:

Name	Value
$align	value of align argumet
$alt	value of alt argumet
$caption	caption text
$class	value of class argumet
$data	value of data argumet
$desc	value of desc argument
$dollar	replaced with dollar sign ($)
$height	image height
$href	hyperlink url when clicking on an image
$id	value of id argumet
$magnifyIcon	enlage-icon
$mousein	value of mousein argument
$mouseout	value of mouseout argument
$n	replaced with a linefeed (\n)
$nop	replaced with empty string
$origheight	image height of the original image
$origsrc	url of the original image (not the resized one)
$origwidth	image width of the original image
$percnt	replaced with percent sign (%)
$src	image source url
$style	value of style argumet
$text	link text to be displayed in the "link" layout type
$thumbfile	thumbnail image file name
$title	value of title argument
$width	image width

After the layout has been formatted any further TopicMarkup that might be contained is expanded afterwards. Note, that using $percnt and $dollar evaluation order of TopicMarkup can be changed so that arguments are expanded after the IMAGE tag has been computed, whereas the default evaluation order is left-to-right-inside-out.

REST image service

The ImagePlugin implements a REST handler process to generate thumbnails for image attachments on the fly. This handler is then called in an img tag like this:

<img src='%SCRIPTURLPATH{"rest"}%/ImagePlugin/process?
  topic=web.topic;
  file=attachment;
  width=300;
  height=300'
  ...
/>

Arguments to the process handlers are:

Name	Values	Default
topic	topic where the image is attached	BASEWEB.BASETOPIC
file	image filename
crop	cropping mode
filter	filter to be applied to the image
height	height of thumbnail
refresh	on/off/img to trigger recomputing images	off
rotate	degree to rotate the image
size	geometry of thumbnail
width	width of thumbnail
zoom	switch on/off upscaling	off

Examples

• See also ImagePluginFilterTest for an exhaustive sample and test page
• Resize to 100 pixels, text flows right, with caption

  %IMAGE{"Westminstpalace.jpg" size="100" align="left" caption="This is my caption"}%

• Resize to %THUMBNAIL_SIZE% size, and center image

  %IMAGE{"Westminstpalace.jpg" type="thumb" align="center"}%

Configuration

Links to external images

You can turn on downloading and mirroring of images that link to external sites, Example:

$Foswiki::cfg{ImagePlugin}{RenderExternalImageLinks} = 1;

This will download the image and mirror it on the local site. Use the refresh url parameter to check if the external images has updated.

If you also turn on attaching a mirrored image to the current topic, an additional attachment-record is generated for the downloaded external image. Attachments will be marked as hidden. Note, that any auto-attached image will update the topic and with it its timestamp.

$Foswiki::cfg{ImagePlugin}{AutoAttachExternalImages} = 1;

Installation Instructions

You do not need to install anything in the browser to use this extension. The following instructions are for the administrator who installs the extension on the server.

Open configure, and open the "Extensions" section. "Extensions Operation and Maintenance" Tab → "Install, Update or Remove extensions" Tab. Click the "Search for Extensions" button. Enter part of the extension name or description and press search. Select the desired extension(s) and click install. If an extension is already installed, it will not show up in the search results.

You can also install from the shell by running the extension installer as the web server user: (Be sure to run as the webserver user, not as root!)

cd /path/to/foswiki
perl tools/extension_installer <NameOfExtension> install

If you have any problems, or if the extension isn't available in configure, then you can still install manually from the command-line. See https://foswiki.org/Support/ManuallyInstallingExtensions for more help.

Dependencies

Name	Version	Description
Image::Magick	>=7	Required
LWP::UserAgent	>=0	Required
Foswiki::Plugins::JQueryPlugin	>=4.90	Required
Foswiki::Contrib::CacheContrib	>=0	Required
Foswiki::Contrib::XSendFileContrib	>=1.00	Optional
Foswiki::Plugins::ZonePlugin	>=1.0	Required for Foswiki < 1.1

Change History

19 Jan 2024	added quality parameter; properly integrate js and css into Foswiki's javascript framework; prevent autolinking within image formats; improved api documentation; initial support for %IMAGE in wysiwyg editing
07 Jul 2022	fixed handling of images with atypical orientations stored in exif
03 Jun 2021	moved auto-attach inline images into afterSave handler
05 Jan 2021	fixed method for cropping to retain transparency; make sure captions are shown if specified
26 Oct 2020	added support for native lazy loading of images; rewrite caching of image metadata using Foswiki:Extensions/CacheContrib
12 Nov 2019	performance fixes, i.e. caching ping results; don't render local images by default; fixed processing transparent background; fix file permissions of thumbnails; svgs are images too; pptx, docx, odt and xlsx files are "frameish" as well to ease thumbnailing them; use svgs in tooltips as is, don't resize them
11 Jun 2018	add src option to type parameter to access the thumbnail source being generated
05 Mar 2018	fixed cleaning up old thumbnails of images with brackets in them; added transparent feature; up'ing density converting svg images
09 Sep 2017	fixed filter api; really default crop to off
27 Jul 2017	removed support for Graphics::Magick … not worth it and not a 100% drop-in replacement; performance: don't deliver image blobs by itself, use a redirect instead; removed support for xsendfile protocol as we are redirecting now; improved method to delete unused thumbnails; added support to generate a cover image of a video; better support for gallery renderers (photoswipe, prettyphoto, …); don't process literal blocks; renamed resize rest handler to process (former still there for compatibility)
11 Oct 2016	added image filters with instagram-like presets
31 May 2016	added mime type detection for inline image data that don't specify it; improved support for html5 data
06 Apr 2016	fixed attaching inline data images
01 Apr 2016	fixed resize rest handler returning invalid image data; working around buggy implementations of imagemagick core-dumping on exit
26 Sep 2015	fixed rewrite of html img tags to bail out when width/height units aren't px values; don't auto-render svg to png anymore
17 Jul 2015	optionally extract and convert inline svg to real images; optionally process html img tags and downscale them on the server; add support for Foswiki-2.x
16 Dec 2014	work around call to unofficial internal api to get absolute pub urls; support extracting thumbnails from movies (mp4,mov,m4v,mpeg,mpg and wmv)
17 Sep 2014	added feature to convert inline image data to proper attachments
08 Sep 2014	added rotate parameter
04 Sep 2014	implemented frame and layer parameter for thumbnail extraction from videos, animations and layered images
28 Aug 2014	only render the first frame of a gif animation generating thumbnails; fix orientation of thumbnail as specified in the EXIF metadata; fully specify REST security flags; new parameter output
28 May 2014:	fixed thumbnail handling in afterRenameHandler
16 Apr 2014:	brought back thumb image type
04 Apr 2014:	flag rest handlers that don't require authentication
18 Mar 2014:	support blanks in image names
3 Aug 2013:	rework image tooltip code to use jquery-ui instead of deprecated jquery.tooltip
8 May 2013:	return a 1x1 pixel when calling the image rest handler for a non-existing image
24 May 2013:	update thumbnails whenever a new image of the same name was uploaded
6 May 2013:	some more svg fixes; cleaning up thumbnails now when images are renamed or moved
9 Oct 2012:	added svg support
6 Aug 2012:	respect noautolink tags when rendering external image links
25 Jun 2012:	fixed attaching external images to the right topic; removed unused option AutoAttachThumbnails; fixed processing of non-attached external images; fixed downloading of urls that look like image links but return a different content type
09 Jan 2012:	added new option 'thumbfile' to format string (Foswiki:Main/JoenioCosta); speed improvement by not "ping-ing" each image on display; rendering thumbnails using newer method available in image::magick 6.5.x, the old method faild resizing and cropping on some platforms; removing longdesc from default image templates; now also caching urls to external images that include url params
29 Jun 2011:	fixed detection of image links to the own wiki not to try an external download+mirror
10 Jan 2011:	fixed parsing of mediawiki like params; fixed jquery interface to foswiki preferences; fixed dependency on ZonePlugin to only be required for old foswiki versions; make result of resize REST service cacheable, i.e. don't use a redirect; fixed expansion of standard escapes; improved crop parameter to specify the location of the remaining image relative to the original; added data parameter to interface with jquery code; using md5 now to properly cache thumbnails; mirroring external images now obeys the ATTACHFILESIZELIMIT preference;
12 Feb 2010:	made imagetooltip a proper jQuery plugin; using Foswiki:Extensions/ZonePlugin for faster page loads
17 Nov 2009:	added zoom parameter; fixed manual refresh via url params
24 Sep 2009:	updated imageplugin.template to help XHTML validation (stop rendering empty id attribute)
14 Sep 2009:	using Foswiki's proxy settings instead of ENV; disabled tooltip previews for Internet Explorers
18 Aug 2009:	removed bonus % in template (Foswiki:Main.AndreLichtsteiner, Foswiki:Main.WillNorris)
24 Apr 2009:	converted to foswiki plugin; added thumbnail REST handler; added tooltip preview using jquery; added mirroring of external images; moved image type definitions into a template
11 Feb 2009:	updated documentation examples (Foswiki:Main.WillNorris)
07 Jan 2009:	certified for foswiki/compat
03 Jul 2008:	fixed parsing the type parameter; fixing docu about the default THUMBNAIL_SIZE; added new default format plain; plainify text to be used in a html attribute position, e.g. titles; default to no img alignment; refresh images on a ?refresh=on url param; using LWP::UserAgent instead of LWP::Simple to mirror images; using Resize instead of Scale for higher quality thumbnails; don't encrypt the href param
03 Mar 2008:	make implementation of image mage configurable, defaulting to Graphics::Magick as Image::Magick has got issues using perl accellerators like mod_perl, speedy-cgi
03 Jan 2008:	added processing of remote images
18 Dec 2006:	fixed image lookup order; fixed html formats; added I18N workaround
18 Aug 2006:	fixed html errors; removed references to ImgPlugin thus not showing the magnify-clip; some html and css fixes to resemble closer to the MediaWiki examples
17 Aug 2006:	width and height arguments had no effect; floating images not clearing proberly on IE
16 June 2006:	released into the public
10 May 2006:	Initial version by forking ImgPlugin