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

[Samuel Gougeon]

Hello,

For selecting a ROI of any shape, after displaying the grayplot:

  * plot(x,y) at least a segment around the middle of the grayplot.
    Choose an appropriate  line color.
  * run useditor(gcf().figure_id)
  * interact with the initial segment :
      o click on a link to insert a point
      o click on and drag a point to move it with its links to neighboors
      o double-click on a point to delete it
  * Doing that = define your area. Interactions are not "modal" = after
    running useeditor(), Scilab does not wait for it returning. And when
    the editor
    is quit (right-click + Exit), no signal is sent to the console, and
    AFAIK there is
    no way to read out the current status of this editor.
  * Then, gce().children.data returns the XY Nx2 matrix of coordinates
    of your curve.
  * You close it: XY($+1,:) = XY(1,:)

This ends the selection part.

After that, identifying points of your grayplot area being in the curve 
may be done with
point_in_polygon: https://fileexchange.scilab.org/toolboxes/121000
However, this script is not vectorized. So, if your full area has big 
sizes, it may takes a while.

I would not guaranty that point_in_polygon() can be vectorized, but we 
may try to.
It does not look too bad, at first sight :)

HTH
Regards
Samuel

Le 11/03/2016 11:01, Philipp Mühlmann a écrit :
> ...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.
>
>
> _______________________________________________
> users mailing list
> users at lists.scilab.org
> http://lists.scilab.org/mailman/listinfo/users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.scilab.org/pipermail/users/attachments/20160312/471dff80/attachment.htm>