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I have an RGB image obtained from saving the imagesc function as shown below. how to refine/smoothen the edges present in the image.

enter image description here

It consists of sharper edges, where I need to smoothen them. Im not able to find a solution for performing this for an RGB image. Instead of the staircase effect seen in the image I'd like to even out the edges. Please help thanks in advance.

Abirami Anbalagan
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  • How is this different from your [previous question](http://stackoverflow.com/questions/43179988/how-to-trace-the-surface-area-as-well-as-smoothen-a-specific-region-in-an-image)? – beaker Apr 04 '17 at 14:42
  • In my previous question I had done segmentation and masking to smoothen the image. I wanted to know if there are other ways to do it for colour images. – Abirami Anbalagan Apr 05 '17 at 14:46

3 Answers3

1

maybe imresize will help you:

% here im just generating an image similar to yours
A = zeros(20);
for ii = -2:2
    A = A + (ii + 3)*diag(ones(20-abs(ii),1),ii);
end
A([1:5 16:20],:) = 0;A(:,[1:5 16:20]) = 0;
subplot(121);
imagesc(A);
title('original')
% resizing image with bi-linear interpolation
B = imresize(A,100,'bilinear');
subplot(122);
imagesc(B);
title('resized')

EDIT

here I do resize + filtering + rounding:

% generates image
A = zeros(20);
for ii = -2:2
    A = A + (ii + 3)*diag(ones(20-abs(ii),1),ii);
end
A([1:5 16:20],:) = 0;A(:,[1:5 16:20]) = 0;
subplot(121);
imagesc(A);
title('original')
% resizing
B = imresize(A,20,'nearest');
% filtering & rounding
C = ceil(imgaussfilt(B,8));
subplot(122);
imagesc(C);
title('resized')

enter image description here

user2999345
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  • Resize is making the image look blurred!!! How to overcome the staircase effect that has been generated? Thank you so much for the answer! – Abirami Anbalagan Apr 04 '17 at 07:49
1

solution

use imfilter and fspecial to perform a convolution of you image with gaussian.

I = imread('im.png');
H = fspecial('gaussian',5,5);
I2 = imfilter(I,H);

change 'blurlevel' parameter (which determines the gaussian kernel size) to make the image smoother or sharper.

result enter image description here

ibezito
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0

If you are just looking for straighter edges, like an elevation map you can try contourf.

cmap = colormap();
[col,row] = meshgrid(1:size(img,2), 1:size(img,1));
v = linspace(min(img(:)),max(img(:)),size(cmap,1));
contourf(col,row,img,v,'edgecolor','none');
axis('ij');

This produces the following result using a test function that I generated.

enter image description here

jodag
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