opencv decode返回值
时间: 2024-06-08 18:04:30 浏览: 132
OpenCV中的`cv::decode`函数主要用于解码图像数据,通常用于处理从各种编码格式(如JPEG、PNG等)加载的二进制数据。`decode`函数的返回值取决于输入的数据类型和解码操作是否成功。
1. 如果数据是有效的图像数据并且解码成功,`decode`会返回一个`Mat`对象,这个`Mat`存储了解码后的图像数据,其类型和大小取决于原始数据。
2. 如果解码失败或遇到错误,`decode`可能返回一个空`Mat`(`cv::Mat()`),或者抛出一个异常。这通常是由于输入数据无法被识别为有效的图像数据,或者编码格式不正确。
例如,调用代码可能像这样:
```cpp
cv::Mat image;
if (cv::imdecode(input_data, cv::IMREAD_COLOR)) {
// 解码成功,image变量包含解码后的图像
} else {
std::cout << "Decode failed: " << cv::Exception.what() << std::endl;
}
```
相关问题
#!/usr/bin/env python2.7 -- coding: UTF-8 -- import time import cv2 from PIL import Image import numpy as np from PIL import Image import os import sys from pyzbar import pyzbar def main(image_folder_path, output_file_name): img_files = [f for f in os.listdir(image_folder_path) if f.endswith(('.png'))] qr_codes_found = [] print("Image files:") for img_file in img_files: print(img_file) for img_file in img_files: img_path = os.path.join(image_folder_path,img_file) img = cv2.imread(img_path) barcodes = pyzbar.decode(img) for barcode in barcodes: if barcode.type == 'QRCODE': qr_data = barcode.data.decode("utf-8") qr_codes_found.append((img_file, qr_data)) unique_qr_codes = [] for file_name, qr_content in qr_codes_found: if qr_content not in unique_qr_codes: unique_qr_codes.append(qr_content) with open(output_file_name,'w') as f: for qr_content in unique_qr_codes: f.write("{}\n".format(qr_content)) if name == 'main': rtsp_url = "rtsp://127.0.0.1:8554/live" cap = cv2.VideoCapture(rtsp_url) # 判断摄像头是否可用 # 若可用,则获取视频返回值ref和每一帧返回值frame if cap.isOpened(): ref, frame = cap.read() else: ref = False # 间隔帧数 imageNum = 0 sum = 0 timeF = 24 while ref: ref, frame = cap.read() sum += 1 # 每隔timeF获取一张图片并保存到指定目录 # "D:/photo/"根据自己的目录修改 if (sum % timeF == 0): # 格式转变,BGRtoRGB frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB) # 转变成Image frame = Image.fromarray(np.uint8(frame)) frame = np.array(frame) # RGBtoBGR满足opencv显示格式 frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR) imageNum = imageNum + 1 cv2.imwrite("/root/Pictures/Pictures" + str(imageNum) + '.png', frame) print("success to get frame") # 1毫秒刷新一次 k = cv2.waitKey(1) # 按q退出 # 如果按下的是q键,则退出循环 if k == ord('q'): cap.release() image_folder_path = '/root/Pictures' output_file_name = 'qr_codes_found.txt' main(image_folder_path,output_file_name)无法生成所需文本
根据您提供的代码,我注意到您的`main`函数缩进不正确,这可能导致代码执行时出现问题。确保在定义`main`函数时函数体内的所有代码都正确缩进请尝试使用以下代码替换您的代码,以确保`main`函数及其调用位于正确位置:
```python
import time
import cv2
from PIL import Image
import numpy as np
import os
from pyzbar import pyzbar
def main(image_folder_path, output_file_name):
img_files = [f for f in os.listdir(image_folder_path) if f.endswith('.png')]
qr_codes_found = []
print("Image files:")
for img_file in img_files:
print(img_file)
for img_file in img_files:
img_path = os.path.join(image_folder_path, img_file)
img = cv2.imread(img_path)
barcodes = pyzbar.decode(img)
for barcode in barcodes:
if barcode.type == 'QRCODE':
qr_data = barcode.data.decode("utf-8")
qr_codes_found.append((img_file, qr_data))
unique_qr_codes = []
for file_name, qr_content in qr_codes_found:
if qr_content not in unique_qr_codes:
unique_qr_codes.append(qr_content)
with open(output_file_name, 'w') as f:
for qr_content in unique_qr_codes:
f.write("{}\n".format(qr_content))
if __name__ == '__main__':
rtsp_url = "rtsp://127.0.0.1:8554/live"
cap = cv2.VideoCapture(rtsp_url)
# 判断摄像头是否可用
# 若可用,则获取视频返回值ref和每一帧返回值frame
if cap.isOpened():
ref, frame = cap.read()
else:
ref = False
# 间隔帧数
imageNum = 0
sum = 0
timeF = 24
while ref:
ref, frame = cap.read()
sum += 1
# 每隔timeF获取一张图片并保存到指定目录
# "D:/photo/"根据自己的目录修改
if (sum % timeF == 0):
# 格式转变,BGRtoRGB
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
# 转变成Image
frame = Image.fromarray(np.uint8(frame))
frame = np.array(frame)
# RGBtoBGR满足opencv显示格式
frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR)
imageNum = imageNum + 1
cv2.imwrite("/root/Pictures/Pictures" + str(imageNum) + '.png', frame)
print("success to get frame")
# 1毫秒刷新一次
k = cv2.waitKey(1)
# 按q退出
# 如果按下的是q键,则退出循环
if k == ord('q'):
cap.release()
image_folder_path = '/root/Pictures'
output_file_name = 'qr_codes_found.txt'
main(image_folder_path, output_file_name)
```
请注意,上述代码假设`image_folder_path`是您要处理的图像文件所在的实际文件夹路径,并将结果写入名为`qr_codes_found.txt`的输出文件中。确保根据需要修改这些值。另外,请确保您的代码中没有其他语法错误或逻辑错误,这可能会导致生成所需文本的问题。
将#!/usr/bin/env python2.7 -- coding: UTF-8 -- import time import cv2 from PIL import Image import numpy as np from PIL import Image if name == 'main': rtsp_url = "rtsp://127.0.0.1:8554/live" cap = cv2.VideoCapture(rtsp_url) #判断摄像头是否可用 #若可用,则获取视频返回值ref和每一帧返回值frame if cap.isOpened(): ref, frame = cap.read() else: ref = False #间隔帧数 imageNum = 0 sum=0 timeF = 24 while ref: ref,frame=cap.read() sum+=1 #每隔timeF获取一张图片并保存到指定目录 #"D:/photo/"根据自己的目录修改 if (sum % timeF == 0): # 格式转变,BGRtoRGB frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB) # 转变成Image frame = Image.fromarray(np.uint8(frame)) frame = np.array(frame) # RGBtoBGR满足opencv显示格式 frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR) imageNum = imageNum + 1 cv2.imwrite("/root/Pictures/Pictures" + str(imageNum) + '.png', frame) print("success to get frame") #1毫秒刷新一次 k = cv2.waitKey(1) #按q退出 #if k==27:则为按ESC退出 if k == ord('q'): cap.release() break和#!/usr/bin/env python2.7 coding=UTF-8 import os import sys import cv2 from pyzbar import pyzbar def main(image_folder_path, output_file_name): img_files = [f for f in os.listdir(image_folder_path) if f.endswith(('.png'))] qr_codes_found = [] print("Image files:") for img_file in img_files: print(img_file) for img_file in img_files: img_path = os.path.join(image_folder_path,img_file) img = cv2.imread(img_path) barcodes = pyzbar.decode(img) for barcode in barcodes: if barcode.type == 'QRCODE': qr_data = barcode.data.decode("utf-8") qr_codes_found.append((img_file, qr_data)) unique_qr_codes = [] for file_name, qr_content in qr_codes_found: if qr_content not in unique_qr_codes: unique_qr_codes.append(qr_content) with open(output_file_name,'w') as f: for qr_content in unique_qr_codes: f.write("{}\n".format(qr_content)) if name == "main": image_folder_path = '/root/Pictures' output_file_name = 'qr_codes_found.txt' main(image_folder_path,output_file_name)合并一下
您可以将两个代码合并为一个ROS节点,以便在同一个程序中运行。下面是合并后的代码:
```python
#!/usr/bin/env python2.7
# -*- coding: UTF-8 -*-
import time
import cv2
from PIL import Image
import numpy as np
from PIL import Image
import os
import sys
from pyzbar import pyzbar
from std_msgs.msg import String
import rospy
def capture_and_recognize():
# 初始化ROS节点
rospy.init_node('capture_and_recognize_node', anonymous=True)
# 创建图像识别结果的发布者
pub = rospy.Publisher('recognition_result', String, queue_size=10)
# 设置摄像头参数
rtsp_url = "rtsp://127.0.0.1:8554/live"
cap = cv2.VideoCapture(rtsp_url)
# 判断摄像头是否可用
# 若可用,则获取视频返回值ref和每一帧返回值frame
if cap.isOpened():
ref, frame = cap.read()
else:
ref = False
# 间隔帧数
imageNum = 0
sum = 0
timeF = 24
while ref:
ref, frame = cap.read()
sum += 1
# 每隔timeF获取一张图片并保存到指定目录
# "D:/photo/"根据自己的目录修改
if (sum % timeF == 0):
# 格式转变,BGRtoRGB
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
# 转变成Image
frame = Image.fromarray(np.uint8(frame))
frame = np.array(frame)
# RGBtoBGR满足opencv显示格式
frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR)
imageNum = imageNum + 1
cv2.imwrite("/root/Pictures/Pictures" + str(imageNum) + '.png', frame)
print("success to get frame")
# 图像识别
img_path = "/root/Pictures/Pictures" + str(imageNum) + '.png'
img = cv2.imread(img_path)
barcodes = pyzbar.decode(img)
qr_codes_found = []
for barcode in barcodes:
if barcode.type == 'QRCODE':
qr_data = barcode.data.decode("utf-8")
qr_codes_found.append(qr_data)
unique_qr_codes = []
for qr_content in qr_codes_found:
if qr_content not in unique_qr_codes:
unique_qr_codes.append(qr_content)
# 发布图像识别结果
for qr_content in unique_qr_codes:
pub.publish(qr_content)
# 1毫秒刷新一次
k = cv2.waitKey(1)
# 按q退出
# 如果按下的是q键,则退出循环
if k == ord('q'):
cap.release()
break
if __name__ == '__main__':
try:
capture_and_recognize()
except rospy.ROSInterruptException:
pass
```
在这个合并的代码中,我们使用了ROS的Python库rospy来创建一个ROS节点。我们初始化了一个节点,创建了一个用于发布图像识别结果的话题,并在适当的位置发布识别结果。您可以根据需要进一步调整代码以满足您的机器人运行环境的要求。