UsageLast updated: 15 October 2024

The most common form of template tag used: all the parameters required to identify the source image and the manipulations and transformations required are included within the tag itself. 

To avoid any parsing confusion within the EE parse system, JCOGS Image single tags can use either image or single as the opening / closing tag element as required.

Illustration

{exp:jcogs_img:image width='300px' save_type='webp' aspect_ratio='16_9' crop='y' max='400' class='kittens' add_dims="yes" flip='v'}

The example tag given above will generate the image shown, via this HTML img tag:

<img src="https://domain.com/images/jcogs_img/cache/local_cache_image_file_name.webp" class="kittens" width="300" height="168">

Note that options chosen for the JCOGS Image tag parameters have resulted in output from the tag which comprises: 

• a well formed HTML img tag
• the img tag includes image dimensions
• the img tag includes the attribute class='kittens'

Also, the chosen JCOGS Image parameters have resulted in the image referenced in the img tag being:

• a cached copy of a local image file which in turn is a modified version of the source file
• cropped to give version of the original image shrunk to 300px wide
• with a 16x9 aspect ratio
• an image content which is the source image flipped vertically, and
• saved in the webp format.

JCOGS Image's default 'smart scale' crop means the image height has was reduced to maintian the requested 16x9 aspect ratio (over-riding both the height and max parameters included in the example).

JCOGS Image can also be accessed via the tag-pair form where a tag has an opening element (similar to the single-tag form described above) and also a closing element. Information can be passed to the add-on both from parameters placed within the opening tag and from the information enclosed between the opening and closing tag elements.

When a closing tag is defined JCOGS Image will process any parameters specified in the opening tag and replace any Image variables specified within the enclosed content with information relevant to the processed image. This approach allows you to create your own customised HTML output, and is particularly useful for creating the image content required by complex HTML image tags such as <figure> and <picture>.

For example:

{exp:jcogs_img:pair 
    src='{images}' 
    width='500px' 
    height='700px' 
    max_height="350px" 
    min="240px" 
    aspect_ratio='16_9' 
    crop='y' 
    save_type='webp' 
    allow_scale_larger='y' 
    class='cats' 
    rotate="35"
    flip='h'}
<figure>
    <img src="{made}" {attributes}="" width="{width}" height="{height}">
    <figcaption>This picture is called {name}.{extension}</figcaption>
</figure>
{/exp:jcogs_img:pair}

will generate this HTML output:

And this picture:

Note: the dimensions reported for the processed image are not those specified in the opening tag - this is because of the rotation, and the width / height reported in the img tag are the dimensions required for the bounding box such that the rotated image can be placed on the page without distortion.

As is the case with single tag version of JCOGS Image, tag pairs can use any of  image single or pair as the method name in the opening / closing tag element as required.

Sometimes developers have to design templates to work with blocks of content that may contain one or more images added by content editors: the JCOGS Image bulk tag offers a way to apply some image processing to these images to (for example) ensure that they are optimally sized and in the ideal image format.

The bulk tag uses the tag-pair format, and searchs the template content enclosed by its opening / closing tags for <img> tags; any tags found are processed by JCOGS Image using the parameters found in the opening bulk tag. 

The bulk tag is most often used to apply 'standard' modifications to all the images within a content block (e.g. making all the images the same size / aspect ratio, applying a standard filter to each, converting all to a preferred image format etc.). JCOGS Image's intelligent handling of class, style and pass-through attributes also makes it easy for the developer to add a range of attributes to the <img> tags - for example adding one or more classes or inline styles to each <img>, or adding implementation specific attributes (such as data-* attributes) or the inlining of javascript events (such as onclick=). 

Illustration

For example:

{exp:jcogs_img:bulk 
    width='300px' 
    aspect_ratio='16_9' 
    crop='y' 
    save_type='webp' 
    allow_scale_larger='y' 
    class='cats' 
    flip='h'}
<p>
    Macavity, Macavity, there’s no one like Macavity,
    There never was a Cat of such deceitfulness and suavity.
</p>
<img src="{images}" width="700px">
<p>
    He always has an alibi, and one or two to spare:
    At whatever time the deed took place—MACAVITY WASN’T THERE!
</p>
    <img src="https://images.unsplash.com/photo-1591871937573-74dbba515c4c">
{/exp:jcogs_img:bulk}

will generate HTML output like this:

<p>Macavity, Macavity, there’s no one like Macavity,
                    There never was a Cat of such deceitfulness and suavity.</p>
                <img src="/images/jcogs_img/cache/blackcatbeach_-_1f4_-_756febcb244c6154cd0d3540ea5cb3b794af4774.jpg" alt="cats">
                <p>He always has an alibi, and one or two to spare:
                    At whatever time the deed took place—MACAVITY WASN’T THERE!</p>
                <img src="/images/jcogs_img/cache/photo-1620196244888-d31ff5bbf163_-_1f4_-_756febcb244c6154cd0d3540ea5cb3b794af4774.jpg" alt="cats">

This in turn will create output that looks like this: 

The palette pair type tag that gives you access to an analysis of the colours that appear in a processed image. It is broadly similar in function to the CE-Image ‘top_colors’ parameter.

The palette for the image is determined using a well regarded algorithm called Modified Median Cut Quantization. The maximum number of colours in the palette can be controlled through the palette_size parameter, which must be at least 2.

The tag supports some special variables:

• {dominant_color} - the rgba() colour code for the image's dominant colour
• {colors}…{/colors} - a variable pair that loops through the palette values identified for the image. The values exposed by this variable pair are:
  • {color} returns the rgb() color value of a palette colour
  • {rank} returns the ordinal rank of the palette colour (#1 being the dominant colour)

Illustration

The size tag is included for backward compatibility with early installations of CE Image.

The tag is a clone of the Image tag, and takes all the same parameters.

JCOGS Image's Action Link system allows you to add images processed by JCOGS Image to any web page whether or not it is part of an ExpressionEngine template. 

There are a variety of uses for Action Links, but the foremost is as a way to offer a more flexible way of integrating images with ExpressonEngine sites that use template caching. Although there are a variety of approaches used, the aim of template caching is to make it possible to send the content of an ExpressionEngine web page to a user without having to process the template that is used to generate the content; doing this speeds up retrieval of the information. When a template is cached usually the links to images within the template are saved as “hard coded” urls - when the cached template is sent to a browser there is no opportunity to check that these images are available (or indeed, modify them to suit changing circumstances). 

If you get JCOGS Image to save the link to the processed image as an Action Link, it is the Action Link that is ‘hard coded’ into the cached content - and when the cached template is then sent to the browser, it is the Action Link that it tries to open. The Action Link triggers JCOGS Image which checks to see if the requested processed image is in the cache, the cached image is returned; if the image is missing, the Action Link contains enough information to allow JCOGS Image to regenerate the required image (and save it to the cache so future attempts to retrieve the same automatic action link image will be cache-fast).

Using JCOGS Image automatic Action Links in this way makes it possible for you to worry less about ensuring that your image cache and template cache are both ‘in sync’ - when you are using automatic Action LInks, clearing the image cache does not also require you to also clear all / any templates that have been cached. But there are also other uses for Action Links - particularly the “manual” version.

Generating an Image via a manual Action Link

JCOGS Image's Action Link system let's you process ‘single’ JCOGS Image tags via an ExpressionEngine ACT link. This feature allows you to add images processed by JCOGS Image to any web page whether or not it is part of an ExpressionEngine template. To do this you need to find the correct action link code for your server, and then append the JCOGS Image parameters that define the image you want to generate to the URL as “GET” variables. 

For example, imagine you have a JCOGS Image tag in your template that looks like this: 

{exp:jcogs_img:image src="/images/of/cats/small.webp" width="350px" aspect_ratio="1_1" crop="yes"}. 

If the action link URL for a server is https://domain.com/?ACT=44 then you could replicate the output of this tag using the following URL:

https://domain.com/?ACT=44&src=/images/of/cats/small.webp&width=350px&aspect_ratio=1_1&crop=yes

When this URL is evaluated (e.g. by pasting into a browser url bar) it contacts JCOGS Image on your server which then looks to see the processed image for this set of parameters is already in the cache, and if not it processes the options just like it would in a template, and then either way returns the processed image. If action links like this are placed in the src attribute of HTML <img> tags, the image returned is treated as the tag “source” and will appear within your HTML template just like any other image referenced by a regular URL.

Automatic Action Links

JCOGS Image can also generate Action Link URLs automatically (the Action Link appears in place of the URL to the processed image that is normally appears in JCOGS Image tag output). You can activate automatic Action Link generation either by setting a default option on the JCOGS Image System Settings panel or by by adding the parameter action_link='yes' to a JCOGS Image tag. 

When you enable automatic Action Links, a specially formatted Action Link will be generated that can be used as in the src= attribute of an HTML <img> tag; when this special Action Link is evaluated by an HTML tag it makes a call to your ExpressionEngine server looking for the processed image created by JCOGS Image when the action link was generated. 

• If the processed image is found in the image cache, ExpressionEngine returns it immediately and the image is displayed in your page. 
• If the processed image is not found in the image cache, JCOGS Image will regenerate the image (and save it in the cache for next time) and return the image. JCOGS Image can do this regeneration without having to make any calls to the wider ExpressionEngine environment (as all the information JCOGS Image needs to reprocess the image is stored in the automatic Action Link) which makes regeneration speedy.

JCOGS Image has strong compatibility with the stalwart CE Image add-on, offering developers a simpler upgrade path to EE5, EE6 and EE7 for sites developed using the CE-Img add-on.

Drop-in compatibility

Although JCOGS Image is based on a completely new image processing code base, it is possible to upgrade an existing site to JCOGS Image without loss of function simply doing a search / replace on the CE Image tag name - so for example {exp:ce_img:single...} would change to {exp:jcogs_img:single...}. In most cases the templates will generate output similar to that produced with CE Image.

Note: Some CE Image functions are not replicated (e.g. ASCIIart) and for some advanced uses (e.g. filters) there are some differences in how some settings work. Sections later in this document for more complete compatibility information.

CE Image Parameter Compatibility Table

Parameter	CE Image Compatibility	Notes
add_dimensions	New feature
add_dims	Full
allow_scale_larger	Full
ascii_art	Not implemented	Unlikely to be replicated.
aspect_ratio	New feature
attributes	Full
auto_cache	N/A	File caching is handled differently by JCOGS Image - see separate notes
auto_sharpen	New feature
aws_auto_url	Not implemented	Could be implemented in a future version if demand for this exists
bg_color	Full
bg_color_default	Not implemented	Currently available via Control Panel option. Could be replicated as a parameter if demand for this exists.
border	Full	Added in version 1.1
bucket	Not implemented	File caching is handled differently by JCOGS Image - see separate notes
cache	New feature	This parameter allows the cache setting for an image to be set at the tag level.
cache_dir	Full
consolidate_class_style	New feature
create_tag	Full
crop	Full	JCOGS Image's implementation of crop includes additional features not present in the CE Image crop parameter.
debug	Not implemented	Deprecated in CE Image. Comprehensive debugging information available via Control Panel option.
default_img_width	New feature
disable_browser_checks	New feature
disable_xss_check	Not implemented	XSS checks on paths provided are not optional.
encode_urls	N/A	JCOGS Image uses a different approach to file names and so this is not needed
exclude_class	New feature
exclude_regex	Full	CE Image's version of this tag only searches within the src= attribute of the tag, the JCOGS Image version will search all the attribute values enclosed within the tag.
exclude_style	New feature
face_crop_margin	New feature
face_detect_sensitivity	New feature
fallback_src	Full
filename	Full
filename_prefix	Full
filename_suffix	Full
filter	Full	Not all the filter options available in CE Image are currently implemented, see separate notes on this in the Filters section of this document.
fit	New feature
flip	Full
force_remote	N/A	This behaviour is handled automatically, there is no equivalent operation
hash_filename	Full
height	Full
hide_relative_path	N/A	JCOGS Image uses a different approach to file names and paths and so this is not needed
image_path_prefix	New feature
interlace	Full
lazy	New feature	Implements automatic lazy-loading for tags generated by the add-on.
manipulate	Not implemented	Could be replicated if demand for this exists
max	Full
max_height	Full
max_width	Full
min	Full
min_height	Full
min_width	Full
output	Full
overwrite_cache	Full
palette_size	Partial	Related tag is broadly similar in function to the CE-Image ‘top_colors’ parameter.
png_quality	New feature
preload	New feature	Implements automatic image preloading for tags generated by the add-on.
quality	Full
reflection	Full
remote_cache_time	N/A	File caching is handled differently by JCOGS Image - see separate notes
remote_dir	N/A	File caching is handled differently by JCOGS Image - see separate notes
rotate	Full
rounded_corners	Partial	Added in version 1.3. Separately specified colour backgrounds for each corner for non-transparent image formats not supported.
save_type	Full
sizes	New feature
src	Full
srcset	New feature	Automatically add responsive variants of the processed image to an <img> tag via the srcset= and sizes= parameters
svg_passthrough	New feature
text	Full	Added in version 1.1
top_colors	Partial	A broadly similar output is provided by JCOGS Image's palette method.
unique	N/A	File caching is handled differently by JCOGS Image - see separate notes
url_only	Full
use_image_path_prefix	New feature
watermark	Full	Added in version 1.1
width	Full

CE Image Filter Compatibility Table

CE Image Variable Compatibility Table