How I can repeatedly divide a binary image ?
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답변 (3개)
darova
2019년 4월 13일
Use mat2cell()
clc,clear
A = imread('fig3.png');
I = im2bw(A);
k = 128; % divide matrix into 128 parts
[m,n] = size(I);
rows_rest = mod(m,k);
cols_rest = mod(n,k);
nrows = (m-rows_rest)/k *ones(1,k);
ncols = (n-cols_rest)/k *ones(1,k);
nrows(1:rows_rest) = nrows(1:rows_rest) + 1;
ncols(1:cols_rest) = ncols(1:cols_rest) + 1;
C = mat2cell(I,nrows,ncols);
댓글 수: 7
Image Analyst
2019년 4월 14일
Your image is not a power of 2.
Try this code:
clc; % Clear the command window.
clear all;
close all; % Close all figures (except those of imtool.)
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'fig3.png';
folder = pwd;
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
%=======================================================================================
% Read in demo image.
grayImage = imread(fullFileName);
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(grayImage)
if numberOfColorChannels > 1
grayImage = grayImage(:, :, 3);
end
% Make sure it's square
if rows ~= columns
grayImage = imresize(grayImage, [rows, rows]);
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(grayImage)
end
% Display image.
subplot(2, 2, 1);
imshow(grayImage, []);
impixelinfo;
axis('on', 'image');
caption = sprintf('Original image: %d rows by %d columns', rows, columns);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0.05 1 0.95]);
% 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 by ImageAnalyst', 'NumberTitle', 'Off')
drawnow;
% 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.
nnzFunction = @(theBlockStructure) nnz(theBlockStructure.data(:));
% Now do a loop to divide by half each time and count the number of non-zeros.
counter = 1;
newRows = rows;
newCols = columns;
while newRows >= 1
% Round sizes.
newRows = floor(newRows);
newCols = floor(newCols);
% Resize the image.
grayImage = imresize(grayImage, [newRows, newCols], 'nearest');
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(grayImage)
% Show the image
subplot(2, 2, 2);
imshow(grayImage);
axis('on', 'image');
caption = sprintf('%d rows by %d columns', newRows, newCols);
title(caption, 'FontSize', fontSize);
% Count the number of non-zero pixels.
whitePixelCount(counter) = nnz(grayImage);
% Display counts so far.
subplot(2, 2, 3:4);
plot(whitePixelCount, 'b.-', 'MarkerSize', 30);
grid on;
title('White Pixel Count', 'FontSize', fontSize);
xlabel('Image number', 'FontSize', fontSize);
ylabel('Count (Number of White Pixels)', 'FontSize', fontSize);
drawnow;
% Compute half the number of rows and columns.
% May be a fractional number if the rows and columns are not a power of 2.
newRows = (rows / 2);
newCols = (columns / 2);
% Show user the results.
promptMessage = sprintf('%d white pixels in this image.\nDo you want to Continue processing,\nor Quit processing?', whitePixelCount(counter));
titleBarCaption = 'Continue?';
buttonText = questdlg(promptMessage, titleBarCaption, 'Continue', 'Quit', 'Continue');
if contains(buttonText, 'Quit')
return;
end
% Increment index for whitePixelCount array.
counter = counter + 1;
end
% Show in command window.
whitePixelCount
![0001 Screenshot.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/213765/0001%20Screenshot.png)
댓글 수: 4
Image Analyst
2019년 4월 18일
Start with a small image of 16 by 16 pixels and explain step by step what you want as the output at each step.
Walter Roberson
2019년 4월 19일
Code for repeatedly dividing was provided at https://www.mathworks.com/matlabcentral/answers/456856-how-can-i-loop-over-a-binary-image-to-get-4-equal-quadrants-always#answer_371003
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