MATLAB: Image smoothing & sharpening of a particular region in an image

image processingImage Processing Toolboximage sharpeningimage smoothing

 How to apply image smoothing & sharpening to only a particular region of an image?
I'm supposed to take a corrupted and noisy image. Select a particular region of interest. Then apply smoothing and/or sharpening only to that region using MATLAB codes. The code should be generalized i.e i should be able to apply that code to any image. Won't there be problem with selecting the threshold levels for smoothing and/or sharpening for each image, if we are supposed to generalize?

Can anyone give the MATLAB code for the above problem?

Best Answer

I'd just smooth the whole thing and then multiply by the mask defining the regions. There are more efficient methods, but for most situations this will be fine.

blurredImage = conv2(grayImage, ones(15)/15^2, 'same');
grayImage(maskImage) = blurredImage(maskImage);

I don't know what you want to do with thresholds. I guess that might affect how your blurred or sharpened image is created, but you don't say exactly so I can't tell.

Related Solutions

MATLAB: How to remove the pattern from microscopy scanned image

Well obviously sharpening the image won't remove the stripes - if anything it will just make it worse.

Look at the log magnitude of the spectrum. See those spikes? Just erase those and inverse transform. I'm attaching a similar example that you can adapt.

MATLAB: How to display the input image, after when the threshold values exceeds certain limit

It's just 3 lines. Just mask the original image:

binaryImage = grayImage > 150;
maskedImage = zeros(size(grayImage)); % Initialize.

maskedImage(binaryImage) = grayImage(binaryImage);

See the full demo below:

% Demo by ImageAnalyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
fontSize = 14;
% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'coins.png';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, '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
grayImage = imread(fullFileName);
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);
% Display the original gray scale image.


subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 
% Let's compute and display the histogram.
[pixelCount grayLevels] = imhist(grayImage);
subplot(2, 2, 2); 
bar(pixelCount);
grid on;
title('Histogram of original image', 'FontSize', fontSize);
xlim([0 grayLevels(end)]); % Scale x axis manually.
yl = ylim();
line([150 150], [0 yl(2)], 'Color', 'r');
% Threshold at 150
binaryImage = grayImage > 150;
% Display the original gray scale image.
subplot(2, 2, 3);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);
% Mask the image
maskedImage = zeros(size(grayImage)); % Initialize.
% Assign values from grayImage that are > 150.
maskedImage(binaryImage) = grayImage(binaryImage);
% Display the original gray scale image.
subplot(2, 2, 4);
imshow(maskedImage, []);
title('Masked Image', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: How to remove the pattern from microscopy scanned image

MATLAB: How to display the input image, after when the threshold values exceeds certain limit

Related Question