使用 OCR 读取圆形文本 [英] Read circular text using OCR

问题描述

我想阅读对象上的文字.但是 OCR 程序无法识别它.当我给小部分时，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.

I want to read text on the object. But OCR program can't recognize it. When I give the small part, it can recognize. I have to transform circle text to linear text. How can I do this? Thanks.

推荐答案

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.这个函数 logPolar() 可以提供帮助.

you can transform the image from Cartesian coordinate system to Polar coordinate system to prepare circle path text image for OCR program. This function logPolar() can help.

以下是准备圆路径文本图像的一些步骤:

Here are some steps to prepare circle path text image:

1. 使用 HoughCircles() 找到圆的中心.
2. 求平均值并做一些偏移，所以求中心.
3. (可选)从中心裁剪图像的正方形.
4. 执行 logPolar()，然后根据需要旋转它.

1. Find the circles' centers using HoughCircles().
2. Get the mean and do some offset, so get the center.
3. (Optinal) Crop a square of the image from the center.
4. Do logPolar(), then rotate it if necessary.

<小时>

检测圆圈并获得中心的平均值并进行偏移.

---

After detect circles and get the mean of centers and do offset.

裁剪后的图像:

logPolar() 和 rotate()

我的 Python3-OpenCV3.3 代码在这里展示，也许有帮助.

My Python3-OpenCV3.3 code is presented here, maybe it helps.

#!/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()

这篇关于使用 OCR 读取圆形文本的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！