moore neighborhood with jacob stopping criteria

Hello and good day,

I am a newbees in MATLAB Image Processing Toolbox. Currently I am analyzing fire image to find the breadth and length of its dimension. However, using an edge detection method (Sobel), it gives extra elements outside of fire boundary (the edge doesnt close perfectly. I am trying to use bwtraceboundaries as command but it didnt works. I tried to find syntax for Moore Neoghbohood with Jacob stopping criteria but I couldnt understand how to do it correctly. Here are the images I am working on (grayscale>BW>edge detection)

Journal that I refer to is article.

I really hope someone could help me. Thanks