How to make triangle for a synthetic image in gray scale

Helo me trying to make a synthetic image in gray scale with some rectangular shape and triangle but have trouble how to make triangle.

Answer 1

[Image Analyst]

Try this:

rows = 240;
columns = 320;
grayImage = zeros(rows, columns, 'uint8');
xCoords = [100 200 300];
yCoords = [80 160 80];
mask = poly2mask(xCoords, yCoords, rows, columns);
grayImage(mask) = 150; % or whatever value you want.
imshow(grayImage);

[Tabish Raza]

thanx much

Answer 2

[Walter Roberson]

poly2roi()

Answer 3

[Benhassine Nasser edinne]

thank you very mutch

Answer 4

[Benhassine Nasser edinne]

you can make this i.e

fname = uigetfile('*.*'); % gray scale image
Io = imread(fname);
I=Io;
xCoords = [200 512 512];
yCoords = [512 128 512];
mask = poly2mask(xCoords, yCoords, size(I,1), size(I,2));
I(mask) = 0;
Iresult=I;
subplot(1,3,1);imshow(Io) ;title('original image'); 
subplot(1,3,2);imshow(mask) ;title('triangl mask');
subplot(1,3,3);imshow(Iresult) ;title('Result image');