Python+OpenCV实现文字颜色识别与矩形标定

阿橙

发布时间：2026-10-14| 5人浏览过

原创

本文介绍使用Python和OpenCV进行图像中文字颜色识别及矩形标定的实现方法。通过设定HSV空间下的红、黑、黄三色阈值提取对应文字，并结合中值滤波、开操作与闭操作去除噪声及修复断裂，最终完成对特定颜色文字的精准定位与标注。

Python+OpenCV实现文字颜色识别与矩形标定

近期处理了一个相对基础的图像处理任务，耗时较短完成了代码编写：

测试数据集由客户自行创建，非标准公开数据集：

具体实现代码如下：

核心代码实现


"""
    Code creation time:September 11, 2021
    Author:PanBo
    Realize function:It mainly realizes the recognition and calibration of fonts with different colors
"""
import numpy as np
import cv2 as cv
 
font = cv.FONT_HERSHEY_SIMPLEX
lower_red = np.array([0, 120, 120])
hight_red = np.array([10, 255, 255])
#
lower_black = np.array([0, 0, 0])
height_black = np.array([144, 144, 144])
 
lower_yellow = np.array([10, 230, 230])
height_yellow = np.array([35, 255, 255])
 
frame = cv.imread("test.png")
cv.namedWindow("test_image", cv.WINDOW_AUTOSIZE)
cv.imshow('test_image', frame)
 
img_hsv = cv.cvtColor(frame, cv.COLOR_BGR2HSV)
mask_red = cv.inRange(img_hsv, lower_red, hight_red)
mask_black = cv.inRange(img_hsv, lower_black, height_black)
mask_yellow = cv.inRange(img_hsv, lower_yellow, height_yellow)
 
cv.namedWindow("mask_red", cv.WINDOW_AUTOSIZE)
cv.imshow("mask_red", mask_red)
cv.namedWindow("mask_black", cv.WINDOW_AUTOSIZE)
cv.imshow("mask_black", mask_black)
cv.namedWindow("mask_yellow", cv.WINDOW_AUTOSIZE)
cv.imshow("mask_yellow", mask_yellow)
 
kernel = cv.getStructuringElement(cv.MORPH_RECT, (3, 3))
mask_yellow = cv.morphologyEx(mask_yellow, cv.MORPH_OPEN, kernel)
cv.namedWindow("mask_yellow_open", cv.WINDOW_AUTOSIZE)
cv.imshow("mask_yellow_open", mask_yellow)
 
mask_yellow = cv.morphologyEx(mask_yellow, cv.MORPH_CLOSE, kernel)
cv.namedWindow("mask_yellow_close", cv.WINDOW_AUTOSIZE)
cv.imshow("mask_yellow_close", mask_yellow)
 
mask_black = cv.medianBlur(mask_black, 3)
mask_red = cv.medianBlur(mask_red, 3)
mask_yellow = cv.medianBlur(mask_yellow, 3)
# cv.imshow(" ", mask_green)
 
cnts1, hierarchy1 = cv.findContours(mask_black, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)
cnts2, hierarchy2 = cv.findContours(mask_red, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)
cnts3, hierarchy3 = cv.findContours(mask_yellow, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_NONE)
 
for cnt in cnts1:
    (x, y, w, h) = cv.boundingRect(cnt)
    cv.rectangle(frame, (x, y), (x + w, y + h), (0, 0, 0), 2)
    cv.putText(frame, 'black', (x, y-5), font, 0.7, (0, 0, 25）,2）
for cnt in cnts2:
    (x, y, w, h) = cv.boundingRect(cnt)
    cv.rectangle(frame, (x, y), (x + w, y + h), (0, 0, 255), 2)
    cv.putText(frame, 'red', (x, y - 5), font, 0.7, (0, 0, 255), 2)
 
for cnt in cnts3:
    (x, y, w, h) = cv.boundingRect(cnt)
    cv.rectangle(frame, (x, y), (x + w, y + h), (0, 0, 255), 2)
    cv.putText(frame, 'yellow', (x, y - 5), font, 0.7, (0, 0, 255), 2)
 
cv.namedWindow("output", cv.WINDOW_AUTOSIZE)
cv.imshow("output", frame)
cv.waitKey(0)