Скачать или смотреть Resolving OpenCV Error (-215:Assertion failed) in Image Processing with Python

Discover the solution to the OpenCV error `(-215:Assertion failed)!ssize.empty()` regarding image resizing in Python, with practical examples and tips.
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Resolving OpenCV Error (-215:Assertion failed) in Image Processing with Python

When working with video streams and image processing in Python using OpenCV, developers often encounter various errors. One of the common issues is the (-215:Assertion failed)!ssize.empty() error that occurs during image resizing. This can be daunting, especially if you're sending continuous data from the streamer to a viewer. In this post, we'll explore this error, understand its causes, and provide a clear solution to fix it.

Understanding the Problem

The error message cv2.error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\imgproc\src\resize.cpp:4045: error: (-215:Assertion failed) !ssize.empty() indicates that OpenCV's resize function is failing because the input image size is empty. This situation often emerges in video processing when the frame being processed is not captured correctly or is empty.

Common Causes of the Error

Empty Frame: The cv2.VideoCapture() or any frame receiving method may return an empty frame either if the stream has ended or there's a delay in receiving the data.

Incorrect Data Transmission: Issues in the data sending and receiving process can lead to an empty frame being sent to the viewer.

The Solution

Let's break down the solution into manageable steps to ensure more robust data handling in your OpenCV-based application.

Step 1: Modify Data Transmission Methods

In the original code snippets, the methods used for sending and receiving data may have led to errors. Instead of using recv_string() and send(), switching to recv_pyobj() and send_pyobj() can significantly improve reliability.

Example Changes

In Streamer.py:

Replace:

[[See Video to Reveal this Text or Code Snippet]]

With:

[[See Video to Reveal this Text or Code Snippet]]

In Viewer.py:

Replace:

[[See Video to Reveal this Text or Code Snippet]]

With:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Check Frame Validity Before Resizing

Before attempting to use the cv2.resize() function, it's crucial to verify if the frame is valid and not empty. You can do this by checking if the frame is None or has dimensions.

Example Check

In both Streamer.py and Viewer.py, add the following check before resizing the frame:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Testing the Updated Code

After making these adjustments, run the entire program again. Ensure that data is being streamed successfully from the Streamer.py to Viewer.py, and that valid frames are being received.

Conclusion

The (-215:Assertion failed)!ssize.empty() error can be frustrating, but with careful handling of data transmission and thorough checks for frame validity, this issue can be resolved effectively. By implementing the changes suggested in this post, you'll enhance the reliability of your image processing application using OpenCV.

Happy coding, and feel free to reach out if you have any further questions or need assistance!