Segmentation in an image with a single object in MATLAB - matlab

Question

Here is the picture:
My goal is placing this bird in another image. I tried something with MATLAB, first rgb2gray then imhist to get the bird intensity, then I made a mask, but I always ended up with a mask which included the tree and the clouds.

Answer 1

Here is some code you can use for this task:
clear;
close all;
im = imread('~/Downloads/siraly_www.kepfeltoltes.hu_.jpg');
im = rgb2gray(im);
%// Manually crop the image
im = double(im(620:1619, 2150:3279));
%// Find edges
hedge = vision.EdgeDetector('Method', 'Sobel');
edges = step(hedge, im);
%// Dilate to close edges around object
edges = imdilate(edges, [0 1 0; 1 1 1; 0 1 0]);
%// Find boundary of object
bound = bwboundaries(edges);
bound = bound{1}; % Largest boundary is around object
%// Display image and object boundary
figure; imshow(im, []);
hold on;
plot(bound(:,2), bound(:,1), '.');
hold off;
%// Select all object pixels by filling the boundary
bwobject = false(size(im));
bwobject(sub2ind(size(im), bound(:,1), bound(:,2))) = true;
bwobject = imfill(bwobject, 'holes');
imobject = zeros(size(im));
imobject(bwobject) = im(bwobject);
figure; imshow(imobject, []);
The method used here is:
Manual cropping of the image.
Edge detection using the EdgeDetector object.
Morphological operations to retrieve the object pixels only using imdilate, bwboundaries and imfill.
Here are the object boundaries computed and plotted in the code:
And here is the object cropped from the image: