how can i blur an image background only

suppose i want to blur an dog image backgroung..just background only not the dog..what code should i use for this?help please

Answer 1

[DGM]

Using basic tools:

% an image (RGB, uint8)
inpict = imread('peppers.png');
imshow(inpict,'border','tight')

% a mask which selects the BG (I, uint8)
% this happens to be antialiased, but it's not necessary
mask = imread('redpepmask.png');
mask = imcomplement(mask);
imshow(mask,'border','tight')

% blur a copy
blurred = imgaussfilt(inpict,5);

% compose the output
mask = im2double(mask);
outpict = im2double(blurred).*mask + im2double(inpict).*(1-mask);
outpict = im2uint8(outpict);

% show it
imshow(outpict,'border','tight')

See also:

Local blurring meta-answer:

https://www.mathworks.com/matlabcentral/answers/46624-how-can-i-filter-region-of-interest-roi-selected-in-a-3-d-array-image-rgb-without-converting-to#answer_1097553

An example of using roifilt2() on an RGB image can be found here:

https://www.mathworks.com/matlabcentral/answers/367628-apply-imfilter-on-specific-regions-roi-of-rgb-image

An example of doing blurring (hard and soft masks) using basic composition methods and basic MATLAB/IPT tools can be found here:

https://www.mathworks.com/matlabcentral/answers/1651050-creating-a-blur-brush-tool-for-images

An example of doing soft-masked blurring using purpose-built composition tools can be found here (see the last face-blurring example):

https://www.mathworks.com/matlabcentral/answers/578179-fading-shading-an-image