matlab 在图像处理中常用的函数使用（1）

<span style="font-size:18px;">tic; % Start timer.clc; % Clear command window.clearvars; % Get rid of variables from prior run of this m-file.fprintf('Running BlobsDemo.m...\n'); % Message sent to command window.workspace; % Make sure the workspace panel with all the variables is showing.imtool close all;  % Close all imtool figures.format long g;format compact;captionFontSize = 14;% Check that user has the Image Processing Toolbox installed.hasIPT = license('test', 'image_toolbox');if ~hasIPT% User does not have the toolbox installed.message = sprintf('Sorry, but you do not seem to have the Image Processing Toolbox.\nDo you want to try to continue anyway?');reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');if strcmpi(reply, 'No')% User said No, so exit.return;endend% Read in a standard MATLAB demo image of coins (US nickles and dimes, which are 5 cent and 10 cent coins)baseFileName = 'coins.png';folder = fileparts(which(baseFileName)); % Determine where demo folder is (works with all versions).fullFileName = fullfile(folder, baseFileName);if ~exist(fullFileName, 'file')% It doesn't exist in the current folder.% Look on the search path.if ~exist(baseFileName, 'file')% It doesn't exist on the search path either.% Alert user that we can't find the image.warningMessage = sprintf('Error: the input image file\n%s\nwas not found.\nClick OK to exit the demo.', fullFileName);uiwait(warndlg(warningMessage));fprintf(1, 'Finished running BlobsDemo.m.\n');return;end% Found it on the search path.  Construct the file name.fullFileName = baseFileName; % Note: don't prepend the folder.end% If we get here, we should have found the image file.originalImage = imread(fullFileName);% Check to make sure that it is grayscale, just in case the user substituted their own image.[rows, columns, numberOfColorChannels] = size(originalImage);if numberOfColorChannels > 1promptMessage = sprintf('Your image file has %d color channels.\nThis demo was designed for grayscale images.\nDo you want me to convert it to grayscale for you so you can continue?', numberOfColorChannels);button = questdlg(promptMessage, 'Continue', 'Convert and Continue', 'Cancel', 'Convert and Continue');if strcmp(button, 'Cancel')fprintf(1, 'Finished running BlobsDemo.m.\n');return;end% Do the conversion using standard book formulaoriginalImage = rgb2gray(originalImage);end% Display the grayscale image.subplot(3, 3, 1);imshow(originalImage);%%% Maximize the figure window.set(gcf, 'units','normalized','outerposition',[0 0 1 1]);% Force it to display RIGHT NOW (otherwise it might not display until it's all done, unless you've stopped at a breakpoint.)drawnow;caption = sprintf('Original "coins" image showing\n6 nickels (the larger coins) and 4 dimes (the smaller coins).');title(caption, 'FontSize', captionFontSize);axis image; % Make sure image is not artificially stretched because of screen's aspect ratio.%%% Just for fun, let's get its histogram and display it.[pixelCount, grayLevels] = imhist(originalImage);subplot(3, 3, 2);bar(pixelCount);title('Histogram of original image', 'FontSize', captionFontSize);xlim([0 grayLevels(end)]); % Scale x axis manually.grid on;%%% Threshold the image to get a binary image (only 0's and 1's) of class "logical."% Method #1: using im2bw()%   normalizedThresholdValue = 0.4; % In range 0 to 1.%   thresholdValue = normalizedThresholdValue * max(max(originalImage)); % Gray Levels.%   binaryImage = im2bw(originalImage, normalizedThresholdValue);       % One way to threshold to binary% Method #2: using a logical operation.thresholdValue = 100;binaryImage = originalImage > thresholdValue; % Bright objects will be chosen if you use >.% ========== IMPORTANT OPTION ============================================================% Use < if you want to find dark objects instead of bright objects.%   binaryImage = originalImage < thresholdValue; % Dark objects will be chosen if you use <.% Do a "hole fill" to get rid of any background pixels or "holes" inside the blobs.binaryImage = imfill(binaryImage, 'holes');% Show the threshold as a vertical red bar on the histogram.hold on;maxYValue = ylim;line([thresholdValue, thresholdValue], maxYValue, 'Color', 'r');% Place a text label on the bar chart showing the threshold.annotationText = sprintf('Thresholded at %d gray levels', thresholdValue);% For text(), the x and y need to be of the data class "double" so let's cast both to double.text(double(thresholdValue + 5), double(0.5 * maxYValue(2)), annotationText, 'FontSize', 10, 'Color', [0 .5 0]);text(double(thresholdValue - 70), double(0.94 * maxYValue(2)), 'Background', 'FontSize', 10, 'Color', [0 0 .5]);text(double(thresholdValue + 50), double(0.94 * maxYValue(2)), 'Foreground', 'FontSize', 10, 'Color', [0 0 .5]);% Display the binary image.subplot(3, 3, 3);imshow(binaryImage); title('Binary Image, obtained by thresholding', 'FontSize', captionFontSize); </span>