What version are you running?
5.0.6
What's the URL of the page this enhancement relates to, if any?

Describe the enhancement and the motivation for it.
If I modify a .png or .jpg file in a review request, the modified file is listed in the Review Board diff as "This is a binary file. The content cannot be displayed." For common types of of image files (I'd guess that PNG and JPEG probably be good enough 99% of the time), it'd be nice the diff view could display the old and new versions of the image side-by-side. (There are many other better ways to show diffs for two images, but side-by-side comparison would be the simplest start.)
What operating system are you using? What browser?
Firefox 134.0.1 on Windows 11 2023H2
Please provide any additional information below.