Matlab basics-2 : Format conversions in Matlab

Suppose we have an image

aa=imread("image.jpg");

Conversion to grayscale:

we can convert it to gray scale using the following operation

grayaa=rgb2gray(aa);

the matrix grayaa is the gray scale version of the image aa.

rgb2gray converts RGB values to grayscale values by forming a weighted sum of the R, G, and B components:

0.2989 * R + 0.5870 * G + 0.1140 * B



Converting the image into black and white:

It can be done in various ways depending on the threshold values.

bw1=im2bw(aa); %% Converts the image into bw using a default value

bw2=im2bw(aa,i); %%here i lies between 0 and 1. 'i' having a value of 0.3 means a threshold value of nearly 77 ( 0.3*256).

An important observation here is that the input image aa can be a grayscale image, an intensity image or even a RGB image.

If we give a RGB image as an input, MATLAB converts the RGB to grayscale first and then into black and white by itself.