TextPoint, a
recognition- recall CaRP scheme with an alphabet of characters. Fig. 5 shows
some invariant points of letter “A”, which provides a strong cue to locate its
invariant points memorize. If the distance to the closest boundary of the object
exceeds a threshold that point is known as the internal point of an object. For
TextPoints, to form a set of clickable points, a set of internal points of
characters is selected. Here there is a chance of overlap between clickable
point and neighboring character and their tolerance ranges also occluded on the
image generated by the underlying Captcha engine. In determining clickable
points to avoid overlap on CaRP images, the distance between any pair of
clickable points in a character must exceed a threshold by this both can be
separated. Consider an example, if the center of a stroke segment in one
character is selected, the user cannot select the center of a similar stroke
segment in another character. To avoid this, the user must select a different
point from the stroke segment. By this user can ensure that a clickable point
is context-dependent: depending on the character that the point lies in the
same type of structured point may or may not be the clickable point. Even
though the clickable points are known for each character, character recognition
is necessary for locating clickable points on a TextPoints

image. These things cannot be achieved by bots