How can I read png file as binary (0 and 1) in Matlab?

Question

I can read a bmp file as binary ( imread('char/C.bmp') => ans=[1 1 0 0 0] ) but when it comes to png files I cannot ( imread('char/C.png') => ans=[9 7 7 7 7 2] ) .
What should I do to convert binary form?

Answer 1

使用im2bw将图像转换为二进制图像。