Matlab : getrect alternative? -

i'm looking select area of image in matlab using mouse, returning x/y of corners user.

looking online, getrect function in image processing toolbox don't have image processing toolbox.

is open source alternative i.e. on matlab file exchange?

mark

if okay using global variables , callbacks, following do. create function passes (for example) image wish display

function extractblock(i)      % clear global variables (or specific app)     clear global;      % display image     figure;     image(i);      % set callbacks handling of mouse button down, motion, ,     % events against figure     set(gcf,'windowbuttondownfcn',   @mybuttondowncallback, ...             'windowbuttonupfcn',     @mybuttonupcallback,   ...             'windowbuttonmotionfcn', @mybuttonmotioncallback); end 

now define callbacks. start mouse button down event record mouse button has been pressed , position (this callback , others can placed in same file above function):

function mybuttondowncallback(~,~)      global is_button_down;     global rect_start_coord;      is_button_down   = true;      % top left corner of rectangle     rect_start_coord = get(gca,'currentpoint');  end 

now handle mouse motion callback draw (or re-draw) rectangle user moves mouse pointer across image:

function mybuttonmotioncallback(~,~)      global is_button_down;     global rect_start_coord;     global rect_end_coord;     global rectangle_handle;      if ~isempty(is_button_down) && is_button_down          % bottom right corner of rectangle         rect_end_coord = get(gca,'currentpoint');          % top left corner , width , height of          % rectangle (note absolute value forces "open"         % left right - need smarter logic other direction)         x = rect_start_coord(1,1);         y = rect_start_coord(1,2);         w = abs(x-rect_end_coord(1,1));         h = abs(y-rect_end_coord(1,2));          % draw rectangle if width , height positive         if w>0 && h>0              % rectangle drawn in white (better colour needed different             % images?)             if isempty(rectangle_handle)                 % empty rectangle not yet drawn                 rectangle_handle = rectangle('position',[x,y,w,h],'edgecolor','w');             else                 % need redraw                 set(rectangle_handle,'position',[x,y,w,h],'edgecolor','w');             end         end     end   end 

now handle mouse event remove rectangle figure , write out corners of rectangle command window (means return matrix of kind have added if return value desired):

function mybuttonupcallback(~,~)      global is_button_down;     global rectangle_handle;     global rect_start_coord;     global rect_end_coord;      % reset button down flag     is_button_down = false;      % delete rectangle figure     delete(rectangle_handle);      % clear handle     rectangle_handle = [];      % compute top left (tl) , bottom right (br) coordinates     tl = [rect_start_coord(1,1)  rect_start_coord(1,2)];     br = [rect_end_coord(1,1)    rect_end_coord(1,2)];      % compute top right (tr) , bottom left (bl) coordinates     tr = [br(1)  tl(2)];     bl = [tl(1)  br(2)];      % write coordinates command window     fprintf('(%f,%f)\t',tl(1),tl(2));     fprintf('(%f,%f)\n',tr(1),tr(2));     fprintf('(%f,%f)\t',bl(1),bl(2));     fprintf('(%f,%f)\n',br(1),br(2));     fprintf('\n');      % optionally display block image end 

the above quick way extract user-defined block image, logic missing handle rectangle being drawn right left. hope helps!