How to create Boundary Recognition and Region Triangulation concurrently?

Hi guys. How can I fix my code to use Delaunay triangulation by applying alphaShape to just triangulate inside the letters? my code is triangulating the convex-hull of every letter.

Clearly, I want to make a triangulation for every letter by using Delaunay Triangulation and AlphaShape Functions. My m file and xls file are attached here.

My CODE:

 close all
clear all
clc
P = xlsread('input.xlsx',1,'A1:B681');
shp = alphaShape(P);
nor = shp.numRegions;
for i = 1 : nor % i = RegionID
    [trs{i}, pts{i}] = alphaTriangulation(shp,i);
end
for j = 1 : nor
    DT = delaunayTriangulation(pts{1,j}); % DT = delaunayTriangulation(P,C)
    IC = incenter(DT);
    triplot(DT,'r');
    axis ([-100 12000 -100 3500])
    grid on
    hold on
    plot(IC(:,1),IC(:,2),'.r','MarkerSize',10)
    hold on
    plot(DT.Points(:,1),DT.Points(:,2),'.b','MarkerSize',20)
    hold on
    k = convexHull(DT);
    xHull = DT.Points(k,1);
    yHull = DT.Points(k,2);
%     plot(xHull,yHull,'k','LineWidth',2)
end

[Ehsan Ben]

The "alphaShape" is doing right its duty. to check this, you can use "plot(shp)" in the last line of the CODE. The problem is, Delaunay Triangulation is making extra triangles on each letter that these extra triangles are very large in comparison to others.