How to make a crop image with a white color result ?

%%Cropping column off 25%
file=imread('Airplane.tiff');  
CR1=imcrop(file,[128 0 512 512]);
[x,y]=size(CR1);
CRP1=zeros(M,N);
for i=1:x
  for j=1:y
      CRP1(i,j+127)=CR1(i,j);
  end
end
step = step + 1;figure(step); imshow(uint8(CRP1));title('The Watermarked Image with Croping column off 25%');
imwrite(uint8(CRP1),'24.tiff','tiff');

if I run the code the cropping result is a black color, how to change it into a white color? -Thanks for the help-

[rafid jasim]

hi

please how can you get this result, i need that

thanks

Answer 1

[ANKUR KUMAR]

Do you want white space or not any space over cropped area. Refer this. Since you have not pasted the original image, I am taking your attached image as input.

A=imread('24.jpg');
subplot(1,2,1)
imshow(A)
subplot(1,2,2)
[m,n]=size(A);
imshow(A(round(m/2)-100:round(m/2)+100,round(m/2)-100:round(m/2)+100))

[ANKUR KUMAR]

Or if you still wish white color over cropped portion, just replace the black portion with white color code.

file=imread('24.jpg');  
CR1=imcrop(file,[128 0 512 512]);
[x,y]=size(CR1);
CRP1=zeros(x,y);
for i=1:x
  for j=1:y
      CRP1(i,j+200)=CR1(i,j);
  end
end
AA=uint8(CRP1);
AA(AA==0)=255;
imshow(AA);

[rafid jasim]

thanks

Answer 2

[DhaniAri]

Thank u for the help. I look for the white color over cropped partition

[Image Analyst]

You've accepted the answer so I guess it solved it for you, though you didn't explicitly say so.

[DhaniAri]

I'm sorry, i forget to say it on my comment

Answer 3

[Image Analyst]

This will do it:

% Demo by Image Analyst, December, 2020.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clearvars;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
fprintf('Beginning to run %s.m ...\n', mfilename);

%-----------------------------------------------------------------------------------------------------------------------------------
% Read in image.
folder = [];
baseFileName = '24.jpg';
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
	% The file doesn't exist -- didn't find it there in that folder.
	% Check the entire search path (other folders) for the file by stripping off the folder.
	fullFileNameOnSearchPath = baseFileName; % No path this time.
	if ~exist(fullFileNameOnSearchPath, 'file')
		% Still didn't find it.  Alert user.
		errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
		uiwait(warndlg(errorMessage));
		return;
	end
end
grayImage = imread(fullFileName);
[rows, columns, numberOfColorChannels] = size(grayImage)
% Display the test image full size.
subplot(2, 2, 1);
imshow(grayImage, []);
axis('on', 'image');
caption = sprintf('Reference Image : "%s"', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.

% Set up figure properties:
% Enlarge figure to full screen.
hFig1 = gcf;
hFig1.Units = 'Normalized';
hFig1.WindowState = 'maximized';
% 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.
hFig1.Name = 'Demo by Image Analyst';

% Mask to find the black part on the left.
threshold = 5; % Find pixels darker than this.
mask = (grayImage <= threshold);
% Display the image.
subplot(2, 2, 2);
% imhist(grayImage);
imshow(mask, []);
axis('on', 'image');
title('Mask Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

% Find columns that are all zeros
columnsToTurnWhite = all(mask, 1);
% Find rows that are all zeros
rowsToTurnWhite = all(mask, 2);
mask = false(rows, columns); % Erase everything.
% Now turn those rows and columns true (white).
mask(:, columnsToTurnWhite) = true;
mask(rowsToTurnWhite, :) = true;
% Display the image.
subplot(2, 2, 3);
imshow(mask, []);
axis('on', 'image');
title('Mask Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

% Make the rgb image white there
grayImage(mask) = 255;
subplot(2, 2, 4);
imshow(grayImage, []);
axis('on', 'image');
title('Final Image', 'FontSize', fontSize, 'Interpreter', 'None');

fprintf('Done running %s.m ...\n', mfilename);

but notice that there is still a black band there. This is because you used JPG format for your image - a very bad idea. Because JPEG is a lossy image compression format, there are actually some pixels that are not pure zero in some of the dark columns. A good illustration for why you never want to use JPG format. Use PNG instead. To fix, raise the threshold to 25 on line 54.

threshold = 25; % Find pixels darker than this.

That code is attached. Note that the code works for both vertical and horizontal black bands that you want to turn white.