How can I automatically do thresholding multiple images in a folder by for loop?

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Parham Babakhani 2020-5-25

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评论： Parham Babakhani 2020-5-25

Hello everyone. I have 100 images in a folder. I intend to read all the images and threshold it in order to count the black pixels in my image. The problem is that I can only do it for one image and not for all of them. Below is the code that I used for only one image. Any help would be appreciated.

clear all;close all;clc;

      A=imread('1.png');
      [X,map]=imread('1.png');
      A=imresize(A,1);
      figure
      imshow(A)
      figure
      A=rgb2gray(A);
      A=medfilt2(A,[1,1]);
      level = graythresh(A);
      BW = im2bw(X,map,0.45);
      imshow(BW)
      blackpixels_eachtime=sum(BW(:)==0)
      Total_black_pixels=648282;
      RF=((Total_black_pixels-blackpixels_eachtime)/(Total_black_pixels))*100

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Answer 1

Image Analyst 2020-5-25

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Check the FAQ: How do I process a sequence of files?

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Image Analyst 2020-5-25

在 MATLAB Online 中打开

You should not have that inner loop. I made a lot of other fixes, and here is the repaired code:

clc;    % Clear the command window.
fprintf('Beginning to run %s.m.\n', mfilename);
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;
imageList = dir('*.png');
numberOfImages = length(imageList);
for k = 1 : numberOfImages
	fullfileName= fullfile(imageList(k).folder, imageList(k).name);
	rgbImage = imread(fullfileName);
	% Optional display of the image.
	imshow(rgbImage);
	title(imageList(k).name, 'FontSize', fontSize, 'Interpreter', 'none');
	drawnow;
	[rows, columns, numberOfColorChannels] = size(rgbImage);
	if numberOfColorChannels == 3
		% Convert to gray scale.
		grayScaleImg = rgb2gray(rgbImage);
	else
		% It's already gray scale.
		grayScaleImg = rgbImage;
	end
	grayScaleImg = im2bw(grayScaleImg, 0.54);
	
	[~,baseFileNameNoExt,~] = fileparts(fullfileName);
	gsFilename=sprintf('%s_gs.png', baseFileNameNoExt);
% 	imwrite(grayScaleImg, gsFilename);
	blackPixels(k) = sum(grayScaleImg(:)==0);
end
bar(blackPixels, 1);
caption = sprintf('Number of black pixels for %d images', numberOfImages);
title(caption, 'FontSize', fontSize, 'Interpreter', 'none');
xlabel('Image Number', 'FontSize', fontSize);
ylabel('Number of Black Pixels', 'FontSize', fontSize);
grid on;
g = gcf;
g.WindowState = 'maximized'
fprintf('Done running %s.m.\n', mfilename);