Image `source` argument

Where the image was taken from, e.g.:

\Image[https://upload.wikimedia.org/wikipedia/commons/6/68/Akha_cropped_hires.JPG]
{title=A couple}
{source=https://en.wikipedia.org/wiki/Human}

which renders as:

Figure 20. A couple. Source.

The source is automatically inferred for certain known websites, e.g.:

Wikimedia https://upload.wikimedia.org/wikipedia/commons
- from: upload.wikimedia.org/wikipedia/commons/6/68/Akha_cropped_hires.JPG
- to: en.wikipedia.org/wiki/File:Akha_cropped_hires.JPG
Example:
```
\Image[https://upload.wikimedia.org/wikipedia/commons/6/68/Akha_cropped_hires.JPG]
{title=A couple no source}
```
which renders as:
Figure 21. A couple no source. Source.

 Ancestors

 Incoming links

Image