无法使用 findContours opencv 提取数字

Question

我正在尝试从图像中提取手写数字和字母表，为此我遵循了但它仍然没有正确提取数字和字母，也没有提取边界线。

您可以在下面找到结果：

代码：

import cv2
import imutils

# Load image, grayscale, Otsu's threshold
image = cv2.imread('xxx/ocr/pic_crop_2.png')
image = imutils.resize(image, width=375)
img=image.copy()

# Remove border
kernel_vertical = cv2.getStructuringElement(cv2.MORPH_RECT, (1,50))
temp1 = 255 - cv2.morphologyEx(image, cv2.MORPH_CLOSE, kernel_vertical)
horizontal_kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (50,1))
temp2 = 255 - cv2.morphologyEx(image, cv2.MORPH_CLOSE, horizontal_kernel)
temp3 = cv2.add(temp1, temp2)
result = cv2.add(temp3, image)

# Convert to grayscale and Otsu's threshold
gray = cv2.cvtColor(result, cv2.COLOR_BGR2GRAY)
_,thresh = cv2.threshold(gray, 120, 255, cv2.THRESH_OTSU | cv2.THRESH_BINARY_INV)
# thresh=cv2.dilate(thresh,None,iterations=1)

# Find contours and filter using contour area
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[0]
for c in cnts:
    x,y,w,h = cv2.boundingRect(c)
    cv2.rectangle(img, (x, y), (x + w, y + h), (36,255,12), 2)

cv2.imshow('thresh', thresh)
cv2.imshow('img', img)

cv2.waitKey()

我尝试使用拨号但没有成功。请在下面找到示例图片：

Answer 1

你可以检查轮廓区域来解决这个问题。

import cv2

# Load image, grayscale, Otsu's threshold
image = cv2.imread('pic_crop_2.png')
#image = cv2.resize(image, width=375)
img=image.copy()

# Remove border
kernel_vertical = cv2.getStructuringElement(cv2.MORPH_RECT, (1,50))
temp1 = 255 - cv2.morphologyEx(image, cv2.MORPH_CLOSE, kernel_vertical)
horizontal_kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (50,1))
temp2 = 255 - cv2.morphologyEx(image, cv2.MORPH_CLOSE, horizontal_kernel)
temp3 = cv2.add(temp1, temp2)
result = cv2.add(temp3, image)

# Convert to grayscale and Otsu's threshold
gray = cv2.cvtColor(result, cv2.COLOR_BGR2GRAY)
_,thresh = cv2.threshold(gray, 120, 255, cv2.THRESH_OTSU | cv2.THRESH_BINARY_INV)
# thresh=cv2.dilate(thresh,None,iterations=1)

# Find contours and filter using contour area
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[0]
MIN_AREA=200
for c in cnts:
    if cv2.contourArea(c)>MIN_AREA:
        x,y,w,h = cv2.boundingRect(c)
        cv2.rectangle(img, (x, y), (x + w, y + h), (36,255,12), 2)

cv2.imshow('thresh', thresh)
cv2.imshow('img', img)

cv2.waitKey()

Answer 2

似乎 3x3 闭合和二值化效果不错（认为黑色区域有问题，应明确擦除或裁剪）。

无法使用 findContours opencv 提取数字

Unable to extract numbers using findContours opencv

python

ocr

opencv

image-processing