How do I use IMFILTER to high pass filter an image?
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How can I high pass filter an image (A) using IMFILTER(A,H)? What must the filter matrix (H) be to perform a high pass filter?
采纳的回答
Ashish Uthama
2011-8-5
2 个投票
This tutorial might help.
5 个评论
Image Analyst
2011-8-6
I've never seen a panda (the web site's example image) look like that. Looks more like a house cat to me.
Walter Roberson
2011-8-6
One could hypothesize that it is a picture of a Red Panda, which is a small whiskered mammal about the size of a small dog. However, the ears are clearly not right for a red panda. Felis Catus, also known as Felis Domesticus, would seem to be a much better match.
Ivan Spector
2022-4-27
Is the tutorial link above still live? I could not access it and had the same quesiton.
Image Analyst
2022-4-27
It looks like the tutorial is no longer online. The link to the course is:
更多回答（3 个）
Image Analyst
2011-8-6
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.
fontSize = 20;
% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'cameraman.tif';
fullFileName = fullfile(folder, baseFileName);
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
% 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.', 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, 'Position', get(0,'Screensize'));
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off')
% Filter 1
kernel1 = -1 * ones(3)/9;
kernel1(2,2) = 8/9
% Filter the image. Need to cast to single so it can be floating point
% which allows the image to have negative values.
filteredImage = imfilter(single(grayImage), kernel1);
% Display the image.
subplot(2, 2, 2);
imshow(filteredImage, []);
title('Filtered Image', 'FontSize', fontSize);
% Filter 2
kernel2 = [-1 -2 -1; -2 12 -2; -1 -2 -1]/16;
% Filter the image. Need to cast to single so it can be floating point
% which allows the image to have negative values.
filteredImage = imfilter(single(grayImage), kernel2);
% Display the image.
subplot(2, 2, 3);
imshow(filteredImage, []);
title('Filtered Image', 'FontSize', fontSize);
2 个评论
Ashish Uthama
2011-8-8
+1, tagging as a tutorial
Image Analyst
2011-10-12
I've never heard of filter1. imfilter and filter2 should give the same answer.
Tony
2011-8-9
0 个投票
A typical high-pass (or high emphasize filter) would be an unsharp mask.
H = fspecial('unsharp');
Pramod Bhat
2011-8-25
0 个投票
Simple averaging your image can fulfill your need if u are not particular with the pass band.
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