Harry Cresswell

Responsive images with Cloudinary

Responsive images are crucial part of improving website performance. But that doesn’t just mean setting all your images to width: 100%;, height: auto; and calling it a day.

Ideally we want to create multiple versions of each image, sending users the version which best suits their viewing context. If, for example, visitors are using 3G on a mobile device, then we should serve the appropriately scaled images, for the best possible experience.

Cloudinary, a cloud based image solution makes this tedious task somewhat simple, by automatically adapting images for delivery in any context.

The article presents a problem Cloudinary helps solve, then provides a quickstart guide to help you get set up. This is particularly suited to those working with static or serverless sites, where hosting images directly within a repository can lead to issues down the line.

The Problem

When building static sites, in the past I’ve used the gulp-responsive Gulp task to find the original image in the src folder and auto generate multiple sizes at build time. Perhaps this sounds familiar?

Using srcset and a Hugo shortcode, I can serve up the different sizes when required.

Flawless workflow, until deployment. Now I’m committing multiple images for every image on my site to my repository. For sites with lots of images this doesn’t really work out. Build times take forever. You get the picture.

The solution to all this is fairly simple, abstract images assets away from your repo and let a service like Cloudinary take care of your media storage.

Introducing Cloudinary

“Cloudinary simplifies responsive images by dynamically adapting image properties — dimensions, crop, format, quality — on-the-fly and delivering the optimal version based on the content and viewing context.”

By adding transformations – custom parameters set in the URL which we’ll look at later – you can customise your image in any number of ways. Think automatic photoshopping in the cloud.

Using a CDN, Cloudinary delivers media faster based on your visitors location, and now images are out of the repo, build times are back to optimum speeds. Portable also makes total sense. No more syncing your media library when you change environment or make changes down the line.

The next part will look at getting Cloudinary set up to auto generate responsive images.

Getting started with Cloudinary: JS setup

There are a few ways to set up Cloudinary but the Javascript option is perhaps the most straight forward.

Step 1: Create an account with Cloudinary

First, Create an Account at Cloudinary.com, then upload a single high-resolution version of any image. Cloudinary with auto generate responsive sizes for you. Pretty cool.

Step 2: Include Cloudinary in your project

Add Cloudinary to your project by including the core Shrinkwrap JS file in the footer of your page, right above </body>.

<script src="https://cdnjs.cloudflare.com/ajax/libs/cloudinary-core/2.3.0/cloudinary-core-shrinkwrap.min.js">

Step 3: Include images with data-src

Head to your Media Library in Cloudinary and hover over your image thumbnail to grab the URL.

Include your image using data-src not src. This is important so the JS can do it’s thing.

Just after upload/ in the url, include w_auto,c_scale this will ensure basic responsive images.

class="cld-responsive" />

Then add the class cld-resonsive and you’re good to go.

Step 4: Adding the Javascript call

Finally, to initialise the Cloudinary instance call the responsive method in your JavaScript file:

const cl = cloudinary.Cloudinary.new({ cloud_name: 'YOUR_CLOUD_NAME' })

You should now be set up with auto responsive images.

Taking it further

There are a number of ways you can improve the workflow. The main one of which is using transformations which we’ll get onto. But first it’s worth analysis your image performance.

Web Speed Test

Using Web Speed Test we can gather detailed optimisation insights on how changes to image size, format, quality and encoding parameters can improve performance.

Chances are you could make improvements on your image compression. Cloudinary recommends 2 transformations for this

Useful transformations

Adding q_auto to the string of transformations in your URL will handle automatic image quality.

Including f_auto will analyse the image content and select the best format to deliver.

For optimal image performance on retina displays use dpr_auto.

Using a Hugo Shortcode

If you built your site with Hugo, like this one, you’ll likely want to create a Shortcode so you can easily add Cloudinary hosted images to any Markdown file.

Inside site/layouts/shortcodes, create a file named cld.html (as in Cloudinary) and add the following:

<div class="Image">
 data-src="{{ .Site.Params.cloudinary_url }}/w_auto,dpr_auto,c_scale,f_auto,q_auto/{{ .Get "src" }}"
 class="cld-responsive" alt="{{ .Get "alt" }}">
 {{ if .Get "caption"}}
 {{ end }}
 {{ if .Get "caption"}}
 <figcaption>{{ .Get "caption" }}</figcaption>
 {{ end }}

Inside your config.toml file, add:

# Set Cloudinary URL for image hosting
cloudinary_url = "https://res.cloudinary.com/YOUR_CLOUD_NAME/image/upload"

Access your new Shortcode in any markdown file using

# Note: replace straight braces with curly braces (I can’t show the exact code without the shortcode working)
[[< cld src="v1531476921/hc/naming-artboards-in-sketch-organised-albion-03.jpg" alt="" caption="Your Caption" >]]

Where the src is the last part of your image URL.

Cloudinary with Forestry CMS

If you’re building a site for a client, you’ve likely considered using a Git based CMS like Forestry. So content editors can view changes quickly, build times will need to be as fast as possible. In this case using Cloudinary together with Forestry is a great option.

It’s as simple as adding your cloud name, API key and secret to your site’s settings to get started. Head to the Forestry Docs for more on this.

Wrapping up

Responsive images are imperative for both website performance and good user experience. But often the work which goes into making images truly responsive is enough not to bother.

Cloudinary sets out to changes this by generating responsive images automatically and offering a simple solution to optimise and edit your images with custom URL transitions.

For more on Cloudinary, head over to the docs to see what else is possible. Below you’ll find a list of resources referenced in the configuration above.


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