创建一个二进制图像

Question

I have a question concerning the creation of a binary image in MATLAB. I want to create a binary image with 3907x3713 pixels. Each pixel is represented by a position in a matrix (I presume). Each pixel has to be black (so value 0 I guess) except for the pixels between 1000-1500 ( x -axis) and 2000-2500 ( y -axis), these have to be white (value 256 I guess).

First of all I create a matrix with 3907 rows and 3713 columns. I fill these up with zeros (through the function zeros ). But than I get stuck to find an easy way to replace some with the value 256 .

Thank you for your time and help.

Answer 1

zeros function returns an array of double .

To create a really binary image with only black and white colors, convert your array to logical type:

im=logical(zeros(3907, 3713));

This will help to use significally (64 times) less memory.

In such image 0 is used for black, 1 is used for white. No other values are allowed.

So, to create some white pixels use

im(1000:1500,2000:2500) = 1;