字母模糊/裁切功能后，模糊(Letters blurry / fuzzy after crop fu

试图通过坐标列表保存到一个数组来修剪长在几个地方我的形象后的裁剪区域的字母变得非常模糊，我想不通为什么。

原始图像看起来像

裁剪后的图像看起来像

在问题的代码如下：

import numpy as np
import cv2

im2 = cv2.imread('1.jpg')
im = im2.copy()

gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray,(5,5),0)
thresh = cv2.adaptiveThreshold(blur,255,1,1,11,2)


contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)


squares = []

for cnt in contours:
    if cv2.contourArea(cnt)>50:
        [x,y,w,h] = cv2.boundingRect(cnt)

        if  h>28 and h<34:
            rect = (cv2.rectangle(im,(x,y),(x+w,y+h),(255,255,255),3))
            squares.append(cv2.boundingRect(cnt))
            cv2.imwrite('norm1.jpg',im)

crop_img = [[[255, 255, 255] for x in xrange(377)] for x in xrange(377) ]

for s in squares:
    x = s[0]
    y = s[1]
    w = s[2]
    h = s[3]
    img = im[y:y+h,x:x+w]
    for col in range(y,y+h):
        for row in range(x,x+w):
            if img[col - y][row - x].tolist() == [0,0,0]:
                crop_img[col][row] = [0,0,0]
cv2.imwrite("cropped.jpg", np.array(crop_img))

任何帮助将不胜感激！

import numpy as np
import cv2
import matplotlib.pyplot as plt

im2 = cv2.imread('norm1_zps89266edb.jpg')
im = im2.copy()

gray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray,(5,5),0)
ret3,thresh = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)

#we ony want the external contours
contours,hierarchy = cv2.findContours(thresh.copy(),cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE) 
#extract the countours with area > 50
squares = [cnt for cnt in contours if cv2.contourArea(cnt) > 50]

#mask array with the same shape as img (but only 1 channel)
mask = np.zeros((im.shape[0], im.shape[1]))
#draw the contours filled with 255 values. 
cv2.drawContours(mask,squares,-1,255,-1)

newImage = np.where(mask==255, thresh, 255)

plt.imshow(newImage)
plt.show()

cv2.imwrite("cropped.jpg", newImage)

输出：