使用OCR阅读循环文本

Question

我想读取对象上的文字.但是OCR程序无法识别它.当我给出小部分时,它可以识别.我必须将圆形文本转换为线性文本.我怎样才能做到这一点？谢谢.

Answer 1

您可以将图像从笛卡尔坐标系转换为极坐标系,为OCR程序准备圆路径文本图像.这个功能logPolar()可以帮助你.

以下是准备圆路径文本图像的一些步骤:

1. 使用找到圆圈的中心HoughCircles().
2. 得到平均值并做一些偏移,所以得到中心.
3. (Optinal)从中心裁剪图像的正方形.
4. 做logPolar(),然后根据需要旋转它.

检测圆圈后得到中心的平均值并做偏移.

歪曲的形象:

之后logPolar()和rotate()

我的Python3-OpenCV3.3代码在这里展示,也许它有所帮助.

#!/usr/bin/python3
# 2017.10.10 12:44:37 CST
# 2017.10.10 14:08:57 CST
import cv2
import numpy as np

##(1) Read and resize the original image(too big)
img = cv2.imread("circle.png")
img = cv2.resize(img, (W//4, H//4))
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

## (2) Detect circles
circles = cv2.HoughCircles(gray, method=cv2.HOUGH_GRADIENT, dp=1, minDist=3, circles=None, param1=200, param2=100, minRadius = 200, maxRadius=0 )

## make canvas
canvas = img.copy()

## (3) Get the mean of centers and do offset
circles = np.int0(np.array(circles))
x,y,r = 0,0,0
for ptx,pty, radius in circles[0]:
    cv2.circle(canvas, (ptx,pty), radius, (0,255,0), 1, 16)
    x += ptx
    y += pty
    r += radius

cnt = len(circles[0])
x = x//cnt
y = y//cnt
r = r//cnt
x+=5
y-=7

## (4) Draw the labels in red
for r in range(100, r, 20):
    cv2.circle(canvas, (x,y), r, (0, 0, 255), 3, cv2.LINE_AA)
cv2.circle(canvas, (x,y), 3, (0,0,255), -1)

## (5) Crop the image
dr = r + 20
croped = img[y-dr:y+dr+1, x-dr:x+dr+1].copy()

## (6) logPolar and rotate
polar = cv2.logPolar(croped, (dr,dr),80, cv2.WARP_FILL_OUTLIERS )
rotated = cv2.rotate(polar, cv2.ROTATE_90_COUNTERCLOCKWISE)

## (7) Display the result
cv2.imshow("Canvas", canvas)
cv2.imshow("croped", croped)
cv2.imshow("polar", polar)
cv2.imshow("rotated", rotated)

cv2.waitKey();cv2.destroyAllWindows()