adding_images

Blends two images, image1 and image2, with cv::addWeighted(): alpha * image1 + beta * image2 + gamma. The two images are synchronized by their time stamps.

opencv_apps	1.11.14 and later (ROS 1), 3.0.0 and later (ROS 2)
ROS	noetic, ROS One, jazzy, kilted, lyrical and later
OpenCV	any version of the distributions
Group	Image filters, the nodes of which publish the processed image in `~/image`

Usage

# ROS 2
ros2 launch opencv_apps adding_images.launch.xml image1:=/camera/image_raw image2:=/camera2/image_raw approximate_sync:=true debug_view:=false
# ROS 1
roslaunch opencv_apps adding_images.launch image1:=/camera/image_raw image2:=/camera2/image_raw approximate_sync:=true debug_view:=false

Try it with the demo video

Download the input video of the demo above, publish it as image with image_publisher, and run the node on it, in the terminals:

wget https://ros-perception.github.io/opencv_apps/media/clips/tos_bridge.mp4
wget https://ros-perception.github.io/opencv_apps/media/clips/pool.mp4  # image2
# terminal 1: publish the video as image in a loop
ros2 run image_publisher image_publisher_node tos_bridge.mp4 --ros-args -p publish_rate:=10.0 -r image_raw:=image
# terminal 2: run the node with the parameters of the demo
ros2 launch opencv_apps adding_images.launch.xml image1:=image image2:=image2 alpha:=0.5 approximate_sync:=true gamma:=0.0
# terminal 3: run, keep it running
ros2 run image_publisher image_publisher_node pool.mp4 --ros-args -p publish_rate:=10.0 -r image_raw:=image2 -r camera_info:=camera_info2
# terminal 4: view the result
ros2 run rqt_image_view rqt_image_view /adding_images/image

image1 is tos_bridge.mp4 and image2 is pool.mp4, both 960x540.

See Credits of the demo videos for the license of the video.

Subscribed topics

Topic	Type
`camera_info`	`sensor_msgs/msg/CameraInfo`
`image1`	`sensor_msgs/msg/Image`
`image2`	`sensor_msgs/msg/Image`

Published topics

Topic	Type
`~/image`	`sensor_msgs/msg/Image`

Parameters

See also the common parameters.

Name	Type	Default (range)	Changed at run time	Description
`alpha`	double	0.5 (0 - 1)	yes	weight of the first array elements.
`approximate_sync`	bool	true	no, restart the node	Flag of approximate_sync. If this value is false, image1 and image2 synchronize exact time.
`auto_beta`	bool	true	yes	True: Automatically set beta weight as 1 - alpha, False: Use user defined beta weight
`beta`	double	0.5 (0 - 1)	yes	weight of the second array elements.
`gamma`	double	0.0 (0 - 255)	yes	scalar added to each sum.
`queue_size`	int	100	no, restart the node	Specigy queue_size of input image subscribers

Source

src/nodelet/adding_images_nodelet.cpp, launch/adding_images.launch.xml