如何使用 OpenCV 找到红色区域? [英] How to find the RED color regions using OpenCV?

问题描述

我正在尝试制作一个检测红色的程序.但是有时它比平时更暗，所以我不能只使用一个值.检测不同深浅红色的合适范围是多少?我目前使用的范围是 128, 0, 0 - 255, 60, 60 但有时它甚至没有检测到我放在它前面的红色物体.

解决方案

RGB 不是用于特定颜色检测的好颜色空间.HSV 将是一个不错的选择.

对于 RED，您可以选择 HSV 范围 (0,50,20) ~ (5,255,255) 和 (175,50,20)~(180,255,255) 使用以下颜色图.当然，RED range 不是那么精确，但还可以.

代码取自我的另一个答案:

相关答案:

<块引用>

1. 选择使用 `cv::inRange` (OpenCV) 进行颜色检测的正确 HSV 上下边界
2. 如何定义阈值以仅检测图像中的绿色对象:Opencv
3. 如何在 Python-OpenCV 中使用 `cv2.inRange` 检测两种不同的颜色?
4. 检测像素是否为红色

当然，对于具体的问题，也许其他色彩空间也可以.

如何使用 opencv 读取公用事业仪表指针?

I am trying to make a program where I detect red. However sometimes it is darker than usual so I can't just use one value. What is a good range for detecting different shades of red? I am currently using the range 128, 0, 0 - 255, 60, 60 but sometimes it doesn't even detect a red object I put in front of it.

解决方案

RGBis not a good color space for specific color detection. HSV will be a good choice.

For RED, you can choose the HSV range (0,50,20) ~ (5,255,255) and (175,50,20)~(180,255,255)using the following colormap. Of course, the RED range is not that precise, but it is just ok.

The code taken from my another answer: Detect whether a pixel is red or not

#!/usr/bin/python3
# 2018.07.08 10:39:15 CST
# 2018.07.08 11:09:44 CST
import cv2
import numpy as np
## Read and merge
img = cv2.imread("ColorChecker.png")
img_hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)

## Gen lower mask (0-5) and upper mask (175-180) of RED
mask1 = cv2.inRange(img_hsv, (0,50,20), (5,255,255))
mask2 = cv2.inRange(img_hsv, (175,50,20), (180,255,255))

## Merge the mask and crop the red regions
mask = cv2.bitwise_or(mask1, mask2 )
croped = cv2.bitwise_and(img, img, mask=mask)

## Display
cv2.imshow("mask", mask)
cv2.imshow("croped", croped)
cv2.waitKey()

Related answers:

1. Choosing the correct upper and lower HSV boundaries for color detection with`cv::inRange` (OpenCV)
2. How to define a threshold value to detect only green colour objects in an image :Opencv
3. How to detect two different colors using `cv2.inRange` in Python-OpenCV?
4. Detect whether a pixel is red or not

Of course, for the specific question, maybe other color space is also OK.

How to read utility meter needle with opencv?

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