About wordid in image search module

[yang2640]

def add_to_index(self,imname,descr):
""" Take an image with feature descriptors,
project on vocabulary and add to database. """
if self.is_indexed(imname): return print ’indexing’, imname

get the imid

imid = self.get_id(imname)

get the words

imwords = self.voc.project(descr)
nbr_words = imwords.shape[0]

link each word to image

for i in range(nbr_words):
word = imwords[i]

wordid is the word number itself self.con.execute("insert into imwords(imid,wordid,vocname)

      values (?,?,?)", (imid,word,self.voc.name))

store word histogram for image

use pickle to encode NumPy arrays as strings self.con.execute("insert into imhistograms(imid,histogram,vocname)

values (?,?,?)", (imid,pickle.dumps(imwords),self.voc.name))

For the following code:

wordid is the word number itself

self.con.execute("insert into imwords(imid,wordid,vocname)")

In the imwords table, we want to see for a given visual word, which of the images are related to the visual word, so we should insert the (imid,word index) if its word number is non-zero, why do we insert the word number itself? the word number can be the index for one word??