KNN.py

import cv2
import csv
import numpy as np
import math

def get_captcha(filepath="test.png",demo=False):
    captcha_identified = []
    dataset_file = "dataset.csv"
    
    imread = cv2.imread(filepath,0)
    height,width = imread.shape
    roi = imread[0:16,0:width]
    imread=roi 
    #convert to black and white
    mat,bnw = cv2.threshold(imread,127,255,cv2.THRESH_BINARY)
    contours,hierarchy = cv2.findContours(bnw,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
    #get individual datasets
    for index in range(1,len(contours)):
        draw = np.zeros(imread.shape,dtype="uint8")
        draw.fill(255)
        cv2.drawContours(draw,contours,index,(0,0,0),1)
        (x,y,w,h) = cv2.boundingRect(contours[index])
        cropped = imread[y:y+h,x:x+w]
        mar2,bnww = cv2.threshold(cropped,127,255,cv2.THRESH_BINARY)
        cropped = bnww
        
        matrix = np.array(cropped)
        column_values = np.sum(matrix,axis=1)
        row_values = np.sum(matrix,axis=0)
    
        x=0
        for index in range(0,row_values.shape[0]):
            x+=row_values[index]
        
        y=0
        for index in range(0,column_values.shape[0]):
            y+=column_values[index]

        eucs = []

        #read datasets from csv
        with open(dataset_file,'r') as fh:
            csvreader = csv.reader(fh)
            iter=0
            for row in csvreader:
                iter+=1
                if iter<=1:
                    continue
                row[1] = float(row[1])
                row[2] = float(row[2])

            #Euclidean distance Formula
                q1 = (row[1]-x)*(row[1]-x)
                q2 = (row[2]-y)*(row[2]-y)

                euc = math.sqrt(q1+q2)
                eucs.append(euc)
    
        temp_store = eucs.copy()
        temp_store.sort()
        min_euc = temp_store[0]

        if min_euc>x:
            continue

        #finding the index of euclidean distance
        index = eucs.index(min_euc)+1
        captcha_identified.append(index)
        print("identified: "+str(index))

    captcha_identified.reverse()
    
    if demo==False:
        decoded_captcha = ''.join(str(e) for e in captcha_identified)
        if len(captcha_identified)>0:
            print("\n")
            print("DECODED CAPTCHA: ")
            print(captcha_identified[:len(captcha_identified)])
        return decoded_captcha

    if len(captcha_identified)>0:
        print("\n")
        print("CAPTCHA DECODED: ")
        print(captcha_identified[:len(captcha_identified)])
    else:
        print("CAPTCHA DECODING FAILED")        
    cv2.imshow("image",cv2.imread(filepath))
    cv2.waitKey(0)

    cv2.destroyAllWindows()

#print(get_captcha("test.png",True))