masking of region of interest outputted by snake's algorithm

i have an ultrasound image as my input and i have applied snake's algorithm to that image and as my output i am getting an ultrasound image with a contour for my region of interest( although computed manually).But i want a binary image as my output with background as black and region of interest as white(not just contour). i shall be grateful to any help or suggestions.thankyou

[Ameer Hamza]

Can you show an example of the image?

[anshumala rakesh]

this is my input (attachment 1) this is my output after performing snake's algorithm (attachment 2) this is the output that i want (attachment 3)

[Siyu Guo]

If your algorithm can guarantee the result be the closed contour of a region, you can initialized a logical matrix B = false(size(img,1), size(img,2)), set the snake contour pixels in B, and then call bwfill function to fill the region.

[Siyu Guo]

And if the snake contour data is provided as vectors of polygon vertices, I think you can use "fill" function to draw the region.