Region of interest tool

the goal of this GUI is to be able to create mask, and modify it after. We allow the following modifications:

 * Translate the mask
 * Change points location
 * Add points
 * Remove Points

Simple statistical analysis can be done on the ROI defined by the user.

In this example, I use Image Processing for ROI creation. The other steps use array manipulation from MATLAB.

Contents

• Load data
• Mask creation.
• Mask translation
• Add points
• Change points location
• Remove points
• Statistical analysis
• All the step are defined in the GUI

clc, clear all,close all,

Load data

We works on coins.png image

I=imread('coins.png');
I(:,:,1)=I;
I(:,:,2)=I;
I(:,:,3)=I(:,:,1);
imshow(I)

Mask creation.

We use ROIPOLY function to create the Mask

[Mask,xi,yi]=roipoly;
I(:,:,3)=255*Mask;
imshow(I)

Mask translation

In this step, we translate the mask. The user give an initial point and a destination point.

[x,y]=ginput(2);
dx=round(x(2)-x(1));
dy=round(y(2)-y(1));
[m,n]=size(Mask);
if dx>0
    Mask=[zeros(m,dx+1) Mask];
    Mask(:,end-dx:end)=[];
else
    Mask(:,1:-dx)=[];
    Mask(:,end:end-dx)=0;
end
if dy<0
    Mask(1:-dy,:)=[];
    Mask(end:end-dy,:)=0;
else
    Mask(end-dy:end,:)=[];
    Mask=[zeros(dy+1,n);Mask];
end

I(:,:,3)=255*Mask;
imshow(I);
xi=xi+dx;
yi=yi+dy;

Add points

The user click on the location of a new point. The algorithm test the best location of a point considering the distance with the other points.

[x,y]=ginput(1);

[m,ind]=min(sqrt((xi-x).*(xi-x)+(yi-y).*(yi-y)));
xi1=[xi(1:ind) ;x ;xi(ind+1:end)];
yi1=[yi(1:ind); y; yi(ind+1:end)];
xi2=[xi(1:ind-1) ;x ;xi(ind:end)];
yi2=[yi(1:ind-1); y; yi(ind:end)];

d1=sum(sqrt((xi1(1:end)-[xi1(2:end);xi1(1)]).^2+(yi1(1:end)-[yi1(2:end);yi1(1)]).^2));
d2=sum(sqrt((xi2(1:end)-[xi2(2:end);xi1(1)]).^2+(yi2(1:end)-[yi2(2:end);yi2(1)]).^2));
if d1>d2
    xi=xi2;yi=yi2;
else
    xi=xi1;yi=yi1;
end
Mask=roipoly(I,xi,yi);

I(:,:,3)=255*Mask;

imshow(I)

Change points location

The user click on the location of the "bad" point. This points is located with a red circle. A second click gives the new location of the point

[x,y]=ginput(1);

[m,ind]=min(sqrt((xi-x).*(xi-x)+(yi-y).*(yi-y)));
hold on
plot(xi(ind),yi(ind),'ro')
hold off
[xp,yp]=ginput(1);
xi(ind)=xp;
yi(ind)=yp;

[Mask,xj,yj]=roipoly(I,xi,yi);
I(:,:,3)=255*Mask;
imshow(I)

Remove points

In this step, the user can remove points by selecting it.

[x,y]=ginput(1);
[m,ind]=min(sqrt((xi-x).*(xi-x)+(yi-y).*(yi-y)));
xi(ind)=[];
yi(ind)=[];
[Mask,xj,yj]=roipoly(I,xi,yi);
I(:,:,3)=255*Mask;
imshow(I)

Statistical analysis

We do a statistical analysis on the ROI specified above.

M=I(:,:,1);
M=M(Mask);
moyenne=mean(M(:));
maximum=max(M(:));
minimum=min(M(:));

disp(['Max=' num2str(maximum)]);
disp(['Mean=' num2str(moyenne)]);
disp(['Min=' num2str(minimum)]);

Max=255
Mean=209.9265
Min=69

All the step are defined in the GUI

The ROItool GUI contains all the step. ROItool

Published with MATLAB® 7.3