'''
    MO815 - Topicos em Processamento de Imagens
    1s 2003
    Professor Neucimar J. Leite
    14/04/2003
    
    
    Usando propriedade:
        E(f, D(b, c)) = E(E(f, b), c)
'''

def zncc(c1, c2):
    from Numeric import sqrt, sum
    
    L = min(len(c1), len(c2))
    c1 = c1[:L]
    c2 = c2[:L]
    
    s1 = sum(c1)
    s2 = sum(c2)
    s11 = sum(c1*c1)
    s22 = sum(c2*c2)
    s12 = sum(c1*c2)
    
    num = L*s12 - s1*s2
    den = sqrt((L*s11 - s1*s1) * (L*s22 - s2*s2))
    return num/den
    
def find(dict, c, log, cc=0.999998):
    '''
        dict: a dictionary like 
                dict = [['image1.jpg', array([4.453, 4.423])],
                        ['image2.jpg', array([3.453, 7.423])]]
        c: curve, that an array to be compared to each one in the dictionary
        log: log file
        cc: correlation criteria. An image is considered equal to another if
            their ZNCC is greater then cc.
    '''
    pattern = "NOT FOUND"
    log.writelines(["Criteria: corr > " + str(cc) + "\n",
                    "Iterations: " + str(len(c)) + "\n"])
    for img in dict:
        corr = zncc(img[1], c)
#        log.write("corr('" + img[0] + "') = " + str(corr) + "\n")
        log.write(".")
        
        if corr > cc:
            pattern = img[0]
            break

    log.write("\n")
    return pattern

def zncctest():
    from Numeric import array
    
    dict = [[IMAGES_PATH + 'g_Brickm.jpg',
                 array([0.0532445311546,0.169468834996,0.235978707671,0.278851121664,0.309265762568,
                        0.332554519176,0.351151943207,0.36665686965,0.379768908024,0.391187399626])],
             [IMAGES_PATH + 'g_Brkwea_t.jpg',
                 array([0.0150678493083,0.0515709519386,0.0824776962399,0.110843315721,0.136748328805,
                        0.160955861211,0.183814242482,0.205334752798,0.225155994296,0.243682578206])]]
                        
    c = array([0.0150678493083,0.0515709519386,0.0824776962399,0.110843315721,0.136748328805,
               0.160955861211,0.183814242482,0.205334752798,0.225155994296,0.243682578206])
               
    if find(dict, c) == IMAGES_PATH + 'g_Brkwea_t.jpg':
        print 'OK'
    else:
        print 'FUCK'

    return