Question

use MATLAB to upload the following:

an image that you want to process (can be taken yourself or downloaded from the internet)

a script that processes the image in TWO ways.

• manipulates the colors
• averages pixels together
  

Please make sure the script displays the images (like how I did with the 40 and 80 pixel averaging) so I can easily compare them to the original. Make sure to COMMENT your code as well.

Homework 13 Please upload the following: an image that you want to process (can be taken yourself or downloaded from the int a script that processes the image in TWO ways. • manipulates the colors • averages pixels together Please make sure the script displays the images (like how I did with the 40 and 80 pixel averaging sol can easily compare them to the original. Make sure to COMMENT your code as well

Answer 1

1- Manipulating colours

% Read in original RGB image.

rgbImage = imread('flower.png');

% Extract color channels.

redChannel = rgbImage(:,:,1); % Red channel

greenChannel = rgbImage(:,:,2); % Green channel

blueChannel = rgbImage(:,:,3); % Blue channel

% Create an all black channel.

allBlack = zeros(size(rgbImage, 1), size(rgbImage, 2), 'uint8');

% Create color versions of the individual color channels.

just_red = cat(3, redChannel, allBlack, allBlack);

just_green = cat(3, allBlack, greenChannel, allBlack);

just_blue = cat(3, allBlack, allBlack, blueChannel);

% Recombine the individual color channels to create the original RGB image again.

recombinedRGBImage = cat(3, redChannel, greenChannel, blueChannel);

% Display them all.

subplot(3, 3, 2);

imshow(rgbImage);

fontSize = 20;

title('Original RGB Image', 'FontSize', fontSize)

subplot(3, 3, 4);

imshow(just_red);

title('Red Channel in Red', 'FontSize', fontSize)

subplot(3, 3, 5);

imshow(just_green)

title('Green Channel in Green', 'FontSize', fontSize)

subplot(3, 3, 6);

imshow(just_blue);

title('Blue Channel in Blue', 'FontSize', fontSize)

subplot(3, 3, 8);

imshow(recombinedRGBImage);

title('Recombined to Form Original RGB Image Again', 'FontSize', fontSize)

% Set up figure properties:

% Enlarge figure to full screen.

set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0, 1, 1]);

% Get rid of tool bar and pulldown menus that are along top of figure.

% set(gcf, 'Toolbar', 'none', 'Menu', 'none');

% Give a name to the title bar.

set(gcf, 'Name', 'Demo ', 'NumberTitle', 'Off')

2- Averaging pixels

% Demo code to divide the image up into 16 pixel by 16 pixel blocks

% and replace each pixel in the block by the mean,

% of all the gray levels of the pixels in the block.

%

clc;

clearvars;

close all;

workspace;

fontSize = 16;

% Read in a standard MATLAB gray scale demo image.

folder = fullfile(matlabroot, '\toolbox\images\imdemos');

if ~exist(folder, 'dir')

% If that folder does not exist, don't use a folder

% and hope it can find the image on the search path.

folder = [];

end

baseFileName = 'cameraman.tif';

fullFileName = fullfile(folder, baseFileName);

grayImage = imread(fullFileName);

% Get the dimensions of the image. numberOfColorBands should be = 1.

[rows columns numberOfColorBands] = size(grayImage)

% Display the original gray scale image.

subplot(1, 2, 1);

imshow(grayImage, []);

title('Original Grayscale Image', 'FontSize', fontSize);

% Enlarge figure to full screen.

set(gcf, 'Position', get(0,'Screensize'));

set(gcf,'name','Image Analysis Demo','numbertitle','off')

% Define the function that we will apply to each block.

% First in this demo we will take the median gray value in the block

% and create an equal size block where all pixels have the median value.

% Image will be the same size since we are using ones() and so for each block

% there will be a block of 8 by 8 output pixels.

meanFilterFunction = @(theBlockStructure) mean2(theBlockStructure.data(:));

% Block process the image to replace every pixel in the

% 16 pixel by 16 pixel block by the median of the pixels in the block.

blockSize = [16, 16];

blockyImage = blockproc(single(grayImage), blockSize, meanFilterFunction);

[rows columns] = size(blockyImage);

% Display the block median image.

subplot(1, 2, 2);

imshow(blockyImage, []);

caption = sprintf('Block Mean Image\nInput block size = 16\n%d rows by %d columns', rows, columns);

title(caption, 'FontSize', fontSize);