image - 使用openCV从ROS处理深度图像消息

Question

所以我目前正在编写一个应该接收ros图像消息的python脚本，然后将其转换为cv2，以便我可以进行进一步的处理。现在，程序仅接收图像，然后将其输出到一个小窗口中，并将其另存为png。
这是我的代码:

#! /usr/bin/python
import rospy 
from sensor_msgs.msg import Image

from cv_bridge import CvBridge, CvBridgeError
import cv2



bridge = CvBridge()


def image_callback(msg):
     print("Received an image!")

     print(msg.encoding)


try:
    # Convert your ROS Image message to OpenCV2
    # Converting the rgb8 image of the front camera, works fine

    cv2_img = bridge.imgmsg_to_cv2(msg, 'rgb8')

    # Converting the depth images, does not work 

    #cv2_img = bridge.imgmsg_to_cv2(msg, '32FC1')        
    
    
    

except CvBridgeError, e:
    print(e)

else:
    # Save your OpenCV2 image as a png
    cv2.imwrite('camera_image.png', cv2_img)
    cv2.imshow('pic', cv2_img)
    cv2.waitKey(0)

def main():
    rospy.init_node('image_listener')
    #does not work:
    #image_topic = "/pepper/camera/depth/image_raw"
    #works fine:
    image_topic = "/pepper/camera/front/image_raw"
    rospy.Subscriber(image_topic, Image, image_callback)
rospy.spin()


if __name__ == '__main__':
     main()

所以我的问题是，如果我使用前置摄像头的数据，但对深度图像不起作用，我的代码就可以正常工作。
为了确保我得到正确的编码类型，我使用了命令msg.encoding，它告诉我当前ros消息的编码类型。
cv2.imshow的工作方式与前置摄像头图片完全相同，它显示的效果与使用ros image_view时获得的效果相同，但是一旦尝试使用深度图像，我将得到一张全黑或全白的图片，与image_view显示给我什么
Here the depth image i get when i use image_view
Here the depth image i receive when i use the script and cv2.imshow
有没有人有使用cv2处理深度图像的经验，并且可以帮助我使它也可以处理深度图像吗？
我真的很感谢您的帮助:)
最好的祝福

Answer 1

您可以按照以下方式尝试获取深度图像，

    import rospy
    from cv_bridge import CvBridge, CvBridgeError
    from sensor_msgs.msg import Image
    import numpy as np

    def convert_depth_image(ros_image):
        cv_bridge = CvBridge()
        try:
            depth_image = cv_bridge.imgmsg_to_cv2(ros_image, desired_encoding='passthrough')
        except CvBridgeError, e:
            print e
        depth_array = np.array(depth_image, dtype=np.float32)
        np.save("depth_img.npy", depth_array)
        rospy.loginfo(depth_array)
        #To save image as png
        # Apply colormap on depth image (image must be converted to 8-bit per pixel first)
        depth_colormap = cv2.applyColorMap(cv2.convertScaleAbs(depth_image, alpha=0.03), cv2.COLORMAP_JET)
        cv2.imwrite("depth_img.png", depth_colormap)
        #Or you use 
        # depth_array = depth_array.astype(np.uint16)
        # cv2.imwrite("depth_img.png", depth_array)


    def pixel2depth():
        rospy.init_node('pixel2depth',anonymous=True)
        rospy.Subscriber("/pepper/camera/depth/image_raw", Image,callback=convert_depth_image, queue_size=1)
        rospy.spin()

    if __name__ == '__main__':
        pixel2depth()