def compute_histogram_rgb(src, r_bins = 32, g_bins = 32, b_bins= 32):
    #create planes
    rplane = cv.CreateImage(cv.GetSize(src), 8, 1)
    gplane = cv.CreateImage(cv.GetSize(src), 8, 1)
    bplane = cv.CreateImage(cv.GetSize(src), 8, 1)
    planes = [rplane, gplane, bplane]
    cv.Split(src, rplane, gplane, bplane, None)
    #compute histogram
    hist = cv.CreateHist((r_bins, g_bins, b_bins), cv.CV_HIST_ARRAY,
            ranges = ((0, 255),(0, 255), (0, 255)), uniform = True)
    cv.CalcHist(planes, hist)      #compute histogram
    cv.NormalizeHist(hist, 1.0)    #normalize hist
    return hist

>>> import sqlite3
>>> db=sqlite3.connect(':memory:')
>>> cursor=db.cursor()
>>> cursor.execute('create table main(id integer, value float, text text);')
>>> cursor.execute('insert into main values(?,?,?)', (13.5, 12, 111))
>>> cursor.execute('select * from main;').fetchall()
[(13.5, 12.0, u'111')]
>>> class b(object):
...     def __str__(self):
...         return 'just b'
...
>>> print b()
just b
>>> cursor.execute('insert into main values(?,?,?)', (10, 11.0, b() ))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
sqlite3.InterfaceError: Error binding parameter 2 - probably unsupported type.
>>>

>>> import sqlite3
>>> db=sqlite3.connect(':memory:')
>>> cursor=db.cursor()
>>> cursor.execute('create table main(id integer, hist blob);')
>>> cursor.execute('insert into main values(?,?)', (13.5, hist))
InterfaceError: Error binding parameter 1 - probably unsupported type.

db = sqlite3.connect(':memory:')
db.execute('create table main(id, hist)')
db.execute('insert into main values(?,?)', ...)