how to draw border

hi there, i have four set of coordinate and i want to draw line to make a border. after that i want to crop it automatically at the border. here, i attach the illustration for further understanding. please help me.. thank you

http://i1259.photobucket.com/albums/ii548/msaiful89/titik.png

[Thomas]

are you performing these operation on an image, or are you actually plotting the points?

[mohd]

i'm performing these operation on image.. sorry.. i'm forget to tell us

Answer 1

[Thomas]

Since you are performing your operations on an image

I'm assuming you know the coordinates and size of the rectangle you want..

I1=imread('myimage.jpg');   % import your image
%the following step is not necessary but just shows the boundary box..
imshow(I1);
hold on
w=[26 77];
x=[26 555];
y=[426 77];
z=[426 555];
Points = [w;x;z;y;w];   %in desired order
plot( Points(:,1), Points(:,2), 'r-');   % draw bounding box

hold off;

figure
I2=imcrop(I1,[26 77 400 478])   % crop the bounding box
imshow(I2)                     % show cropped image

[mohd]

thanks.. exactly what i want.. thanks a lot mr Thomas Anthony. :-)

[mohd]

why there are 400 and 478 in this code.

I2=imcrop(I1,[26 77 400 478])

400 and 478 stand for what value.

[Thomas]

that is the size of the rectangle 426-26=400(width) and 555-77=428(length)

[mohd]

ok.. thanks:). yes, really understand. :)

Answer 2

[Matt Kindig]

To draw the border, you can just use 'plot':

w=[26 77];
x=[26 555];
y=[426 77];
z=[426 555];
Points = [w;x;z;y;w];   %in desired order
plot( Points(:,1), Points(:,2), 'r-');

What do you mean you want to "crop" your data set at the border?

[Thomas]

I guess the user means to say only see the boxed area in the plot..

In that case add the following line to the code

set(gca,'xlim',[min(Points(:,1)) max(Points(:,1))],'ylim',[min(Points(:,2)) max(Points(:,2))])

[mohd]

i mean i want to crop image at border. here attach the illustration. after make border and i want to crop as in my attachment.

http://i1259.photobucket.com/albums/ii548/msaiful89/crop.png

i hope you can understand what i mean..:) anyway.. thank a lot for helping me..:)