Can I use "keypoint" as a single word?

In technical or academic writing it is always acceptable to use the correct jargon terms for the field.

A quick search on Stack Overflow suggests that "keypoint" as a single word is in reasonably common use.

• Keypoint - 2400 hits: https://stackoverflow.com/search?q=keypoint
• "Key Point" - 6250 hits: https://stackoverflow.com/search?q=%22key+point%22

On the other hand, google searches combining "keypoint" or "Key point" with other image processing terms seem to suggest "keypoint" is somewhat more commonly used. Both are used in academic papers.

If this is for academic work you might want to copy what your instructor or lecturer does.