Hey,
The image is "cut in half" because its' size exceeds the space available in the main content (image is 800px wide; the content area is 580px). Looking at the page source, I can see that the following classes are added to this page: single, single-post, postid-193 and single-format-standard.
You can add CSS to solve this problem, I also note that there is no sidebar content on this page and assuming there won't need to be any sidebar content on any single post pages you can use this code to adjust the width (add at the very end of style.css):
.single #content { width: 980px; }
If however, it is only this page that requires an increased width, you can be selective with the CSS and use the post ID so it's only this page that has the change:
.postid-193 #content { width: 980px; }
Hope this helps!
James