How to change the Image colour of ones and zeros to white and black

Question

Akakan-Abasi Okon 2021-6-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/859840-how-to-change-the-image-colour-of-ones-and-zeros-to-white-and-black

评论： Image Analyst 2021-8-21

IMSC.PNG

The mage has 50 x 100 points (vertical x horizontal dimension). Each point can be zero or one, where zero = white colour and one = black colour.

I tried this

B = randi([0 1],50, 100);

imagesc(B)

The output image is represented with yellow and blue but I want it to be black and white.

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Answer 1

Image Analyst 2021-6-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/859840-how-to-change-the-image-colour-of-ones-and-zeros-to-white-and-black#answer_728010

在 MATLAB Online 中打开

You don't need a colormap. Just try this:

B = randi([0 1],50, 100);
imshow(B)
impixelinfo();

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Image Analyst 2021-6-19

在 MATLAB Online 中打开

copy_paste_image.m

You can use simple indexing. Like

% Demo by Image Analyst
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 = 8;
fprintf('Beginning to run %s.m ...\n', mfilename);
grayImage = imread('moon.tif');
[rows, columns, numberOfColorChannels] = size(grayImage)
numTiles = 5;
r = round(linspace(1, rows+1, numTiles+1))
c = round(linspace(1, columns+1, numTiles+1))
for kr = 1 : numTiles
	row1 = r(kr);
	row2 = r(kr+1) - 1;
	for kc = 1 : numTiles
		col1 = c(kc);
		col2 = c(kc+1) - 1;
		subImage = grayImage(row1:row2, col1:col2, :);
		imshow(subImage);
		caption = sprintf('Rows %d to %d\nColumns %d to %d', row1, row2, col1, col2);
		title(caption, 'fontSize', fontSize);
		drawnow;
		% Delay a fraction of a second so we can see it.
		pause(0.33)
	end
end
fprintf('Done running %s.m.\n', mfilename);

If you want to paste the extracted subimages onto a canvass with some kind of custom placement like you've shown, then you can paste them on to a larger canvass. See my copy and paste demo.

Image Analyst 2021-6-19

在 MATLAB Online 中打开

You didn't post TstDim.jpg, but for the uncla.PNG image you attached this works fine. It goes through the 25 tiles in a 5x5 layout and shows you each tile. Each tile has a reduced dimension (size) because it's 1/5 the size of the original, though it's a pixel-for-pixel sub image extracted from it.

% Demo by Image Analyst
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 = 18;
fprintf('Beginning to run %s.m ...\n', mfilename);
rgbImage = imread('uncla.png');
subplot(1, 2, 1);
imshow(rgbImage)
axis('on', 'image');
title('Original Image', 'FontSize', fontSize);
g = gcf;
[rows, columns, numberOfColorChannels] = size(rgbImage)
numTiles = 5;
r = round(linspace(1, rows+1, numTiles+1))
c = round(linspace(1, columns+1, numTiles+1))
% Draw lines over image.
for k = 1 : numTiles
	xline(c(k), 'Color', 'r', 'LineWidth', 2);
	yline(r(k), 'Color', 'r', 'LineWidth', 2);
end
subplot(1, 2, 2);
loopCounter = 1;
for kr = 1 : numTiles
	row1 = r(kr);
	row2 = r(kr+1) - 1;
	for kc = 1 : numTiles
		col1 = c(kc);
		col2 = c(kc+1) - 1;
		subImage = rgbImage(row1:row2, col1:col2, :);
		imshow(subImage);
		axis('on', 'image');
		caption = sprintf('Tile #%d\nRows %d to %d\nColumns %d to %d', ...
			loopCounter, row1, row2, col1, col2);
		title(caption, 'fontSize', fontSize);
		g.WindowState = 'maximized';
		drawnow;
		loopCounter = loopCounter + 1;
		% Delay a fraction of a second so we can see it.
		pause(0.33)
	end
end
msgbox('Done!');
fprintf('Done running %s.m.\n', mfilename);

But you did not actually ask a question or say if anything is wrong or not what you want. If this didn't work, then be specific because I don't know what else to offer you.

Image Analyst 2021-6-19

在 MATLAB Online 中打开

There are 15 black patches (not 25 and not 20) on a white background canvass. Additionally, the black patches seem to have random heights and to be placed at random row locations. And they black patches to not have the salt and pepper appearance of the images like you said you wanted first. So do you just want to create black patches of random heights and paste them in at random rows for each of the 5 columns?

This code will give you something similar to IMSHW.png:

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 = 15;
canvass = 255 * ones(100, 200, 'uint8');
patchWidth = 35;
for col = 1 : 5
	% Make patch a random height between 16 and 34
	patchHeight = round(16 + 18 * rand(1))
	% Get a random location to paste it
	row1 = 1 + round(15*rand)
	row1bottom = (row1 + patchHeight - 1)
	row2 = round(35 + 15*rand)
	row2bottom = (row2 + patchHeight - 1)
	row3 = round(70 + 15*rand)
	row3bottom = min([100, (row3 + patchHeight - 1)])
	% Get columns
	col1 = (col-1)*40 + 1;
	col2 = col1 + patchWidth - 1;
	% Paste black rectangle onto canvass
	canvass(row1 : row1bottom, col1 : col2) = 0;
	imshow(canvass, []);
	axis('on', 'image');
	canvass(row2 : row2bottom, col1 : col2) = 0;
	imshow(canvass, []);
	axis('on', 'image');
	canvass(row3 : row3bottom, col1 : col2) = 0;
	imshow(canvass, []);
	axis('on', 'image');
end
axis('on', 'image');
fprintf('Done!  Thanks Image Analyst!\n');

Akakan-Abasi Okon 2021-8-21

Thank you Image Analyst, please you can help with this one.

What I actually want is how to remove noise from this noisy image to get back my original image.

Though the recovered image might not look exactly the way it was but should have the rectangular blocks(probably with some distortions) in similar position as it was in the original image.