[Scilab-users] ?= creating ROI from mouse click

[Philipp Mühlmann]

...so to better explain my purpose:

Assumptions:

- one has a 2D Array of data or a gray scale Image
- one wants to select the Region of interest via mouse clicks, by clicking
into the Image
- the ROI can be of any shape (triangle, rectangle, parallelogram, 5-point
star ...etc)
- one wants to Display only the ROI...everything outside of the ROI should
be set to 0

purpose of ROI
- one wants to process only a part of the input Image in such a way that:

 -if Pixel belongs to ROI than process Image
- if Pixel does not belong to ROI do nothing


So since I somehow can't figure it out how to:

- calculate by hand if a pixel is left, right, above or below a line
defined by two points (to bad, i know)

and therfore

- sort pixels in such a way that they either belong to the ROI or not

I use the mentioned approach.


Here the code:


function [ROI, ROIpoints]=RoiImage(img);

    cols = size(img,'c');
    rows = size(img,'r');

    f = figure();
    ShowImage(im,'click with mouse into image');        // use of IDP
function, could be exchanged by Matplot()
    a = gca();
    a.margins = [0 0 0 0];
    messagebox(["left click into the image to get ROI borders";"end
with any other button"], "Information", "info", ["OK"])
    ibutton = 3;
    nr_points = 0;
    while ibutton == 3;
        [ibutton,xcoord,ycoord]=xclick();
        if ibutton == 3 then
            nr_points = nr_points + 1
            plot(xcoord, ycoord,'o');
            ROIpoints(nr_points,:) = double([xcoord ycoord]);
        end
    end

    nr_points = max(size(ROIpoints));

    if nr_points < 3 then
        mprintf('not enough points \n');
        mprintf('ROI requires minimal 3 points \n');

        ROI = 0;
        return;
    end;

    f = figure();
    f.background = 8;
    f.axes_size = [cols,rows];
    x=ROIpoints(:,1);
    y=ROIpoints(:,2);
    xfpolys(x,y,[-1]);      // how does xfpolys know which area to
fill? Is this area stored somewhere as a variable?
    a=gca();

    a.tight_limits = "on";
    a.data_bounds=[0,0;cols,rows];
    a.margins = [0 0 0 0];

    xs2bmp(gcf(),'mask.bmp');

    maskIm = RGB2Gray(ReadImage('mask.bmp'));       // uses IDP functions

    deletefile('mask.bmp');

    ROI = zeros(rows,cols);
    pos = find(maskIm < 255);
    ROI(pos)= 1;

    delete();
endfunction





-- 
There we have the salad.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.scilab.org/pipermail/users/attachments/20160311/d1994586/attachment.htm>