You can change the size yourself.
- Adding
s
to the end of the image link will make it s
mall
- Adding
m
to the end of the image link will make it m
edium size
- Adding
l
to the end of the image link will make it l
arge
- Use the HTML
<img>
tag with the height
and width
attributes
Eg. http://i.stack.imgur.com/GCfgS.png --> http://i.stack.imgur.com/GCfgSm.png for a smaller image.
There are a few more letters you can add, see more at http://api.imgur.com/models/image#thumbs. Quoting from that link:
| Thumbnail Suffix | Thumbnail Name | Thumbnail Size | Keeps Image Proportions |
|------------------|------------------|----------------|-------------------------|
| s | Small Square | 90x90 | No |
| b | Big Square | 160x160 | No |
| t | Small Thumbnail | 160x160 | Yes |
| m | Medium Thumbnail | 320x320 | Yes |
| l | Large Thumbnail | 640x640 | Yes |
| h | Huge Thumbnail | 1024x1024 | Yes |

goes to:

In my experience, for extremely large images (like the one you mention), even adding l
will make it smaller. Eg:
