MATLAB: Morphological closing to crop an image

cropImage Processing ToolboxMATLABmorphological closing

Hi,

I'm trying to use the image processing toolbox to remove extraneous pixels from an image and I'm running into trouble. Basically I have a painmap (attached), which is a blank sheet of paper with a black body template on it, and a patient can draw in red marker over the areas of the body that cause them pain. However, often patients will draw outside of the lines and these are the pixels I'd like to crop out: everything outside of the black body outline. A friend suggested I use morphological closing to accomplish this but I'm not sure how to go about doing this. If anyone has any ideas they would be much appreciated.

Thanks, Matt

Best Answer

No that does not sound right. You'd use masking, assuming you have the original body outline. Closing will smooth out the white parts of the image. You didn't attach anything yet. Why don't you attach and image of the blank sheet, an image where the patient scribbled on it, and what you'd like that image to look like after processing?

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OK, if you really need to it work for a full color image, here is code for that:

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 = 22;
%--------------------------------------------------------------------------------------------------------

%    READ IN IMAGE
folder = pwd;
baseFileName = 'image.jpeg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
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% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(rgbImage);
% Display the image.

hFig = figure;
subplot(2, 2, 1);
imshow(rgbImage, []);
impixelinfo;
title('Original RGB Image', 'FontSize', fontSize, 'Interpreter', 'None');
impixelinfo;
hFig.WindowState = 'maximized'; % May not work in earlier versions of MATLAB.

drawnow;
%--------------------------------------------------------------------------------------------------------
%    EXTRACTION OF IMAGE
% Get the max image
grayImage = min(rgbImage, [], 3);
subplot(2, 2, 2);
imshow(grayImage, []);
impixelinfo;
title('Gray Scale Image', 'FontSize', fontSize, 'Interpreter', 'None');
impixelinfo;
hFig.WindowState = 'maximized'; % May not work in earlier versions of MATLAB.
drawnow;
threshold = 240; % Whatever....
mask = grayImage < threshold; % Create a binary image (a mask)
% Extract the largest blob only.
mask = bwareafilt(mask, 1);
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mask = imfill(mask, 'holes');
% Display the image.
subplot(2, 2, 3);
imshow(mask, []);
title('Mask Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');
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redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
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meanGLR = mean(rgbImage(redChannel > threshold))
meanGLG = mean(rgbImage(greenChannel > threshold))
meanGLB = mean(rgbImage(blueChannel > threshold))
% Mask the individual color channel images.
% Make outside the mask the mean of what's above the threshold.
redChannel(~mask) = meanGLR;
greenChannel(~mask) = meanGLG;
blueChannel(~mask) = meanGLB;
% Recombine separate color channels into a single, true color RGB image.
rgbImage2 = cat(3, redChannel, greenChannel, blueChannel);
% Display the cropped image.
subplot(2, 2, 4);
imshow(rgbImage2, []);
title('Final Image', 'FontSize', fontSize, 'Interpreter', 'None');
axis('on', 'image');

Best Answer

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