Dear Sara,
You can use the function imfinfo to get i.e. the bit depth of the image. With the function rgb2gray you can convert your RGB image into a grey image.
An example how to perform a RGB (24 bitDepth) to a grayscale (8 bitDepth) is shown below:
clc;clear all;close all;
[RGB,map_RGB] = imread('bitdepth_24bpp_580.png');
RGB_info = imfinfo('bitdepth_24bpp_580.png');
RGB_BitDepth_original = RGB_info.BitDepth
Gray= rgb2gray(RGB);
imwrite(Gray,'imagegrey.png');
grey_info = imfinfo('imagegrey.png');
Grey_BitDepth = grey_info.BitDepth
figure(1);
subplot(2,1,1);imshow(RGB,map_RGB);
subplot(2,1,2);imshow(Gray);
The image that I used can be found in the attachment.
Good Luck! Christiaan van Ommeren
