在 UWP C# 中应用高通滤波器

Question

I am trying to apply high pass filter in my UWP windows 10 app. First I am blurring the image. Then I am subtracting blurred image from the original image. The result I have got is like

Where as I have seen different examples of high pass filtering online, the result should like this

I have done this using photoshop. I want to get this result after applying above algorithm, but getting blackish image.

I have followed this article to do it.

Answer 1

I tried to implement what you are trying to do, and thankfully i got a code directly from MATLAB forum, and seems like i am getting pretty good results as you can have a look in the image below.

I think what you are missing here is gray-scaling the image properly.I think you are applying high pass filter directly to colored image and expecting a grayscaled image.

I will also share the code i implemented so that you can also give a try on your end.

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.
Image = imread('highPassFilter.jpg');   % Image from stack over flow

%converting image to grayscale
grayImage=rgb2gray(Image);

% 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);

I hope that helps. Dont forget to upvote or accept as answer if it helps.