small fix

Signed-off-by: Nicola Vigano <nicola.vigano@esrf.fr>

zUtil_GUI/gtGuiCollectPointsFromImage.m

-function points = gtGuiCollectPointsFromImage(map)
+function points = gtGuiCollectPointsFromImage(map, do_rescale)
     f = figure();
     ax = axes('parent', f);
-    map = (map - min(map(:))) ./ (max(map(:)) - min(map(:)));
-    im = imagesc(map, 'parent', ax);
+    if (exist('do_rescale', 'var') && ~isempty(do_rescale) && do_rescale)
+        map = (map - min(map(:))) ./ (max(map(:)) - min(map(:)));
+        im = imagesc(map, 'parent', ax);
+    else
+        im = imshow(map, 'parent', ax);
+    end
 
     cm = uicontextmenu('Parent', f, 'Callback', @(src, evt)save_clicked_point());
     set(im, 'UIContextMenu', cm);