Filling image area that is bound by a Delaunay triangle

Hello,

Let's say that we are treating dot patterns obeying some sort of arrangement on a given image. When calling Matlab's delaunay, the output, DT beneath, will be a Nx3 matrix. Then we can use triplot to plot the triangles,

DT = delaunay(x,y);
triplot(DT,y,x);

Is there any way one can fill a triangle (say the first entry of DT) in the existing image (not a plot/patch)?

Below is an image I borrowed from Matlab's documentation to illustrate the issue I am after:

The solid black triangle.

Thanks!