If you have the Computer Vision Toolbox, you can use insertText() to burn text into the image.
To introduce scratches it depends if they're straight or curved and if they have variable thickness or not. If they're just simple straight lines of one pixel, then simply use rand() to get a point, then again to get a point a distance away from it. You can use rand() to get random numbers for both the angle and length of the scratch. Then use polyfit() to get the equation of the line and polyfit() to get all the coordinates in between those endpoints. Then just loop over those burning some value, such as zero into it.
Is this your homework? Otherwise if your attempts over a half hour don't work let me know and I'll help. It's going to be something like
% Demo by Image Analyst to generate straight line not anti-aliased lines
% (scratches) in a gray scale image.
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
%--------------------------------------------------------------------------------------------------------
% READ IN IMAGE
grayImage = imread('cameraman.tif');
% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage)
if numberOfColorChannels > 1
% It's not really gray scale like we expected - it's color.
% Extract the red channel (so the magenta lines will be white).
grayImage = grayImage(:, :, 1);
end
%--------------------------------------------------------------------------------------------------------
% Display the image.
subplot(1, 2, 1);
imshow(grayImage, []);
axis('on', 'image');
title('Original Image', 'FontSize', fontSize, 'Interpreter', 'None');
impixelinfo;
hFig = gcf;
hFig.WindowState = 'maximized'; % May not work in earlier versions of MATLAB.
drawnow;
numScratches = 200
for s = 1 : numScratches
xy1 = rand(1,2);
x1 = columns * xy1(1);
y1 = rows * xy1(2);
lineLength = 100 * rand(1);
angle = 360 * rand(1);
x2 = x1 + lineLength * cosd(angle);
y2 = y1 + lineLength * sind(angle);
coefficients = polyfit([x1,x2], [y1,y2], 1);
% Get lots of x so we don't have "gaps" in line.
allX = linspace(x1, x2, rows);
allY = round(polyval(coefficients, allX));
% Now round x
allX = round(allX);
for k = 1 : length(allY)
if allY(k) > rows || allX(k) > columns || allY(k) < 1 || allX(k) < 1
continue; % Skip pixels outside of image.
end
grayImage(allY(k), allX(k)) = 0;
end
subplot(1, 2, 2);
imshow(grayImage); % Display your original image.
drawnow;
end
caption = sprintf('With %d scratches in it', numScratches);
title(caption, 'FontSize', fontSize);
Adapt as needed and report back.
