Convert image to gray and binary

a= imread('1.jpg');
subplot(2,2,1);
imshow(a);
subplot(2,2,2);
b=imresize(a,[256 200]);
imshow(b);
subplot(2,2,3);
c=rgb2gray(b);
imshow(c);
subplot(2,2,4);
d=im2bw(c);
imshow(d);