Content: images
Image handling is one of Blurry's strengths, and under the hood, Blurry performs some image magic using ImageMagick.
Blurry image handling improvements
Absolute paths
Blurry converts relative paths in Markdown to absolute paths in the build folder. This enables autocomplete in code editors, which makes for a pleasant writing experience.
srcset and sizes
Blurry generates images of various sizes, specified by the IMAGE_WIDTHS and THUMBNAIL_WIDTH settings. These enable responsive images, using an appropriately sized image for each device.
This improves page speed by ensuring that devices aren't loading larger images than they can display.
AVIF
Rather than rendering images as plain <img> elements, Blurry uses the <picture> element to support AVIF, while providing a fallback for browsers that do not yet support AVIF.
Blurry automatically generates AVIF versions of your images, including the resized images mentioned above.
This improves page speed because AVIF provides excellent image quality at smaller file sizes than other image codecs.
Width & height
Blurry grabs the original image's width and height and includes those values in their corresponding HTML attributes. This tells the browser the image's aspect ratio, so there is enough vertical for the image in the browser DOM.
This protects against layout shifts, which are disruptive for website visitors, especially on mobile devices.
For more information, see the Lighthouse documentation on image aspect ratios.
Lazy loading
Blurry adds lazy loading (loading="lazy") to all images in body content.
This provides a page speed boost by waiting to load most images on a page until they're needed.
Figure caption
Blurry adds the image's alt description as a figure caption (<figcaption>).
Example
Given the following Markdown syntax for an image with dimensions of 2160x1620 and with a MAXIMUM_IMAGE_WIDTH setting of 750px:
standard Markdown processing might output:
<img alt="Screenshot of Black's playground" src="./images/black-playground.png">
When configured with a maximum image width of 750px, Blurry's image plugin, by contrast, outputs:
<figure>
<picture>
<source srcset="/images/black-playground-285.avif 285w, /images/black-playground-360.avif 360w, /images/black-playground-640.avif 640w, /images/black-playground-750.avif 750w"
sizes="(max-width: 285px) 285px, (max-width: 360px) 360px, (max-width: 640px) 640px, 750px">
<img alt="Screenshot of Black's playground"
loading="lazy"
src="/images/black-playground.png"
sizes="(max-width: 285px) 285px, (max-width: 360px) 360px, (max-width: 640px) 640px, 750px"
srcset="/images/black-playground-285.png 285w, /images/black-playground-360.png 360w, /images/black-playground-640.png 640w, /images/black-playground-750.png 750w"
width="2160"
height="1620">
</picture>
<figcaption>Screenshot of Black's playground</figcaption>
</figure>