Markers in Matlab

In addition to the post for Harris detector I will share some code for marking the objects and points in an image. When I needed some ready-to-use Matlab function (R2009b) I did not find anything. There is such a block in the Simulink Image Processing blockset, however there is no equivalent M-code function in Matlab. So, I was forced to create my own marker function to view the results of my code and to develope my programs.

So here is the code for "+" marker :

function [draw_img]=draw_cross_marker(img,y,x,R,G,B)

% Draw Marker

%Drawing Markers in the image img. The marker is +. There is no other choice.

%The color of the marker is defining by R,G,B values.R,G and B values

%should be in range [0,255].

%y and x are vectors with equal lenghts containing coordinates of y and x in matrix coordinate

%system of the points where should be put a marker. The function take a raw

%image "img" and return the same image with markers drawn on it.

[size_m,~]=size(y);

for i=1:1:size_m

        img(y(i),x(i),1)=R;

        img(y(i),x(i),2)=G;

        img(y(i),x(i),3)=B;

        img(y(i)+1,x(i),1)=R;

        img(y(i)+1,x(i),2)=G;

        img(y(i)+1,x(i),3)=B;

        img(y(i)-1,x(i),1)=R;

        img(y(i)-1,x(i),2)=G;

        img(y(i)-1,x(i),3)=B;

        img(y(i),x(i)+1,1)=R;

        img(y(i),x(i)+1,2)=G;

        img(y(i),x(i)+1,3)=B;

        img(y(i),x(i)-1,1)=R;

        img(y(i),x(i)-1,2)=G;

        img(y(i),x(i)-1,3)=B;

end

    draw_img=img;

And here is the code for rectangular maker:

function [draw_img]=draw_rectangle_marker(img,RectSize,y,x,R,G,B)

% Draw Marker

%[draw_img]=draw_rectangle_marker(img,RectSize,y,x,R,G,B)

%Drawing Markers in image img. The marker is a rectangle. There is no other choice.

%The color of the marker is defining by R,G,B values.R,G and B values

%should be in range [0,255]. RectSize - the size of the rectangle.

%"y" and "x" are vectors with equal lenghts containing coordinates of y and x in matrix coordinate

%system of the points where should be put a marker.

%The function take raw a image img and return the same image with markers on it.

SemiSize=round(RectSize/2);

y1=y-SemiSize;

x1=x-SemiSize;

for i=x1:1:x1+RectSize

    for j=y1:1:y1+RectSize

    if (((i==x1)||(i==x1+RectSize))||((j==y1)||(j==y1+RectSize)))

        img(j,i,1)=R;

        img(j,i,2)=G;

        img(j,i,3)=B;

    end

    end

end

draw_img=img;

The result of the cross marker function can be seen in the Feature Points Detection - Harris Detector post.