cv-bridge

1.13.0.post0 verified Fri May 01 auth: no python

CvBridge converts between ROS Image messages and OpenCV images. Current version is 1.13.0.post0. Release cadence follows ROS distributions.

pip install cv-bridge

Common errors

error ImportError: No module named cv_bridge ↓

cause cv-bridge package not installed.

fix

Run pip install cv-bridge or install ROS environment with cv-bridge.

error AttributeError: module 'cv_bridge' has no attribute 'CvBridge' ↓

cause Trying to import CvBridge from wrong location, e.g., `import cv_bridge` then `cv_bridge.CvBridge()`.

fix

Use correct import: from cv_bridge import CvBridge then instantiate with CvBridge().

error RuntimeError: cv_bridge exception: ... ↓

cause Invalid encoding string or incompatible image formats.

fix

Ensure encoding matches the actual image type. Common: 'bgr8', 'rgb8', 'mono8'.

Warnings

gotcha Forgetting to specify `desired_encoding` results in default encoding which may not match expected format. Always specify encoding explicitly. ↓

fix Use `desired_encoding='bgr8'` (or appropriate encoding) in `imgmsg_to_cv2`.

gotcha OpenCV uses BGR channel order, but most other libraries use RGB. Converting to/from ROS Image without specifying encoding can swap channels. ↓

fix Always set encoding to 'bgr8' for OpenCV compatibility.

deprecated The `cv_bridge.boost.cv_bridge_boost` module is deprecated and may be removed in future versions. ↓

fix Use `from cv_bridge import CvBridge` instead of importing boost submodules.

Imports

CvBridge
wrong
```
from cv_bridge.cv_bridge import CvBridge
```
correct
```
from cv_bridge import CvBridge
```
The direct import from the package is shorter and correct.

Quickstart

Basic usage of CvBridge to convert between ROS Image messages and OpenCV images.

import cv2
from cv_bridge import CvBridge
from sensor_msgs.msg import Image

bridge = CvBridge()
# Convert a ROS Image message to OpenCV image
cv_image = bridge.imgmsg_to_cv2(image_message, desired_encoding='bgr8')
# Convert back
image_message = bridge.cv2_to_imgmsg(cv_image, encoding='bgr8')