python - How to make a for loop from left to right, top to bottom in Python?

Question

I am trying to make a QR Code, and be able to read the data that is on the code itself. I am able to write the information, as well as see the bit values for the QR Code. When I read the QR Code through the code I have written, it gives me a completely different set of bits than what was written.

Code for reading the QR Code:

i,j=150,150
    step=37
    charRep=""
    for byte in range(150,450):
        color=int(img[i,j])
        # ~ print(color)
        if (color==int(255)):
            charRep+="0"
        elif (color==int(0)):
            charRep+="1"
        i+=step
        if i>=412:
            i=150
            j+=step
            if j>=412:
                break

    show(img)

The QR Code:

This QR Code, with my code, says "Test", in binary notation, with the first character being the top row, the second the one below, so on.

The way I have my code for writing onto the QR Code template is I take the bits and write them, left to right, top to bottom. However, my code doesn't read back the data from the QR Code in the same way. I am wondering what to change with my code to make it work properly.

Minimal Reproducible Example Code:

import numpy as np
import cv2

def show(img,wait=0,destroy=True):
    img=np.uint8(img)
    cv2.imshow("image",img)
    cv2.waitKey(wait)
    if destroy:
        cv2.destroyAllWindows()

def straighten(img,data):
    color = cv2.cvtColor(img, cv2.COLOR_GRAY2BGR)

    contours, hierarchy = cv2.findContours(img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
    # ~ print(len(contours))
    cv2.drawContours(color, contours, -1, (0,255,0), 3)
    # ~ show(color)

    targets=[]
    while len(contours):
        contour=contours.pop()
        _,x,y=stats(contour)
        friends=[]
        for index,c in enumerate(contours):
            _,i,j=stats(c)
            if np.hypot(x-i,y-j)<5:
                friends.append(index)
        for index in friends[::-1]:
            del contours[index]
        targets.append((len(friends)+1,x,y))
    targets.sort()
    targets=targets[-4:]

    points=np.float32([[500,500],[500,100],[100,100],[100,500]])
    source=np.float32([[x,y] for c,x,y in targets])
    M=cv2.getPerspectiveTransform(source,points)
    dst=cv2.warpPerspective(img, M, (600,600))
    _,img=cv2.threshold(dst,127,255,cv2.THRESH_BINARY)
    
    i,j=150,150
    step=37
    charRep=""
    for byte in range(150,450):
        color=int(img[i,j])
        # ~ print(color)
        if (color==int(255)):
            charRep+="0"
        elif (color==int(0)):
            charRep+="1"
        i+=step
        if i>=412:
            i=150
            j+=step
            if j>=412:
                break
    print(charRep)
    show(img)


def stats(contour):
    M = cv2.moments(contour)
    return M['m00'],(M['m10']/M['m00']),(M['m01']/M['m00'])
def data2bits(data):
    bits=""
    for i in range(len(data)):
        binary=str(bin(ord(data[i])))
        binary=binary.replace("0b","0")
        binary=binary.zfill(8)
        bits+=binary
        # ~ print(bits)

    bits=bits.ljust(64,'0')
    print("\nThese are the bits of the data you put in:\n"+str(bits)+"\n")
    return bits
    
def bits2pixels(bits,qrCode):
    i,j=150,150
    step=37
    for bit in bits:
        if (bit=="1"):
            dim = 37
            color=(0,0,0)
        elif (bit=="0"):
            i+=step
            if i>=412:
                i=150
                j+=step
                if j>=412:
                    break
            continue
        cv2.rectangle(qrCode,(i,j),(i+dim,j+dim),color,-1)
        i+=step
        if i>=412:
            i=150
            j+=step
            if j>=412:
                break
    show(qrCode)
    return(qrCode)

def bits2data(bits):
    string_blocks = (bits[i:i+8] for i in range(0, len(bits), 8))
    string = ''.join(chr(int(char, 2)) for char in string_blocks)
    print("This is the data you typed in, converted from the bits:\n"+str(string))
qrCode=cv2.imread("scan.png",0)
data=input("Put in the data you want and you will get the binary output for the first 8 characters.\nIf the data put in is less than 8 characters long, the bits will be filled up\nbut will be removed when the data is recompiled.\nType in your data: ")
data=data[:8]
bits=data2bits(data)
qrCode=bits2pixels(bits,qrCode)
bits2data(bits)

straighten(qrCode,data)

标签： pythonloops