Decompress "/depth/depth_registered/compressed" after rosbag recording fails

Software ROS1
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1

Using rosbag to record compressedDepth images is failing to decompress on python, the resulting image ends up binary, losing all depth information.

depth_np_arr = np.frombuffer(msg.data, np.uint16)
cv_image_depth = cv.imdecode(depth_np_arr, cv.IMREAD_UNCHANGED)
2

Hi @Shaza-Kaoud
You cannot directly read a compressed image.
You must subscribe to it by using the appropriate camera subscriber:
http://wiki.ros.org/rospy_tutorials/Tutorials/WritingImagePublisherSubscriber

3

I had a subscriber, basically while creating the bagfile, now the compressedDepth image is unit16 and compressed with JPEG instead of PNG, I can decompress the color image normally, the problem is with the depth and how it was formed by the wrapper, no normal flow would work:

It seams like the openni option makes the data go through an unsupported flow

4

You must remember that the standard depth mode uses 32bit float data, OpenNI instead uses 16 bit unsigned int data.
So you must correctly transform the data

5

Yes, I can not find a standard transformation for the 16-bit unsigned int data that had undergone JPEG compression, opencv ends up converting to a binary image!

6

Thank you so much @Myzhar for the attempts. Apparently, the file I was trying to read was recorded before the 3.7 release of the wrapper. Release v3.7.x · stereolabs/zed-ros-wrapper · GitHub , before the openni fix

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