Image Operations

Images are separate files and as such just embedded into HTML files. However very often you want to perform modifications on these images that require interacting with those files directly. This can be conveniently done directly from the template code through the image APIs that Lektor provides.

Accessing Images

To work with images one needs to get access to the image objects first. Images are returned from the attachments of a page. If you want to make sure you only operate with actual images the .images attribute can be used to filter the query. For instance this iterates over all attached images of a page:

{% for image in this.attachments.images %}
  <div class="image"><img src="{{ image|url }}"></div>
{% endfor %}

To access images from a different content folder, you would use:

{% for image in site.get('/myfolder').attachments.images %}
  <div class="image"><img src="{{ image|url }}"></div>
{% endfor %}

To retrieve only a specific image or attachment with a certain name you would use

{% set my_image = site.get('/myfolder').attachments.get('imagenameexample.jpg') %}
  <div class="image"><img src="{{ my_image|url }}"></div>

Accessing Image Data

One of the more common operations is to access the direct image data. This is resolution and file format. The width, height and format parameters are provided for this. In some cases this is very useful to generate CSS code that needs to know about the original resolution. For instance this achieves a retina rendered background:

<div style="
  background: url({{ image|url }});
  background-size: {{ image.width / 2 }}px {{ image.height / 2 }}px
"></div>

Accessing EXIF Data

Lektor can also give you access to a lot of the EXIF information that is stored in the images. Not all EXIF information is available but the most common values are. For the full list of attributes see EXIF data.

Here an example that shows the camera information:

<div class="image">
  <img src="{{ image|url }}" alt="">
  <p><strong>Camera:</strong> {{ image.exif.camera }}
</div>

Generating Thumbnails

While browsers are reasonably good at downscaling images themselves, you still need to transmit the entire image. When you want smaller images it often makes sense to generate thumbnails automatically. In Lektor each image provides the thumbnail method.

It accepts the width and height of the target image. If either of these is not provided, it will be computed automatically. The return value can be converted into a URL with the |url filter:

<img src="{{ image.thumbnail(320)|url }}">