检测像素是否为红色 [英] Detect whether a pixel is red or not

问题描述

我们可以如下定义HSV中红色的范围.我想检测某个像素是否为红色?如何在Python中做到这一点?我花了一整天，但找不到解决方案.请解决我的问题.我是Python的新手.我正在使用的代码是:

We can define the range of red color in HSV as below. I want to detect that whether a certain pixel is red or not? How can I do that in Python? I spend whole day, but unable to find solution. Please resolve my problem. I'm very new to Python. Code that I'm using is:

img=cv2.imread("img.png")
img_hsv=cv2.cvtColor(img, cv2.COLOR_BGR2HSV)

# lower mask (0-10)
lower_red = np.array([0,50,50])
upper_red = np.array([10,255,255])
mask0 = cv2.inRange(img_hsv, lower_red, upper_red)

# upper mask (170-180)
lower_red = np.array([170,50,50])
upper_red = np.array([180,255,255])
mask1 = cv2.inRange(img_hsv, lower_red, upper_red)
image_height,image_width,_=img.shape    
for i in range(image_height):
   for j in range(image_width):
       if img_hsv[i][j][1]>=lower_red and img_hsv[i][j][1]<=upper_red:
          print("Found red")

推荐答案

您几乎是正确的.您可以将较低RED和较高RED的蒙版合并到一个蒙版中.

You are almost right. You can merge the masks of lower RED and higher RED together to a single mask.

为此ColorChecker.png:

找到红色的步骤:

1. 读取图像并转换为hsv.

我使用此色图选择红色范围(lower 0~5, upper 175~180):

I choose the red ranges (lower 0~5, upper 175~180) using this colormap:

1. 然后合并遮罩，您可以通过遮罩判断像素是否为红色.或裁剪"区域以进行可视化:

#!/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()

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