Can an improvement to an existing implementation be publishable?

My master thesis is an improvement of a code. I gave this code about one year and half ago from the author of the one paper.

After working on his code, I improve the result. but my implementation is not a lot. My added part to his code is less than 300 lines.

The base paper was published on 2013 in the journal with impact factor 2 .

My question is "improvements works" have the ability to send to a journal? Or when you can send your work to journal which you should develop the whole things.

By the way the issue which I am working on is one of the new standard.