Error in image.html template

```
<img {% if object.float %}class="{{ object.float }}" {% endif %}alt="{% if object.alt %}{{ object.alt }}{% endif %}" src="{% thumbnail object.image image_size %}" />
```

but
    context.update({
        'picture':instance,
        'link':link, 
        'image_size': u'%sx%s' % (width, height),
        'placeholder':placeholder
    })
