title: Image Operations
---
summary: Shows how templates can work with images.
---
sort_key: 30
---
body:

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:

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

## 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:

```html+jinja
<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
:ref](../../api/db/record/exif/).

Here an example that shows the camera information:

```html+jinja
<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 :ref](../../api/db/record/thumbnail/) method.

It accepts the width and height of the target image.  If the height is not
provided it will be scaled proportionally.  The return value can be converted
into a URL with the `|url` filter:

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