ROS Published Image Zoom Out

when i use $roslaunch zed_wrapper zed2.launch received ROS topic,I found the image size is 640×360(720P)、960×540(1080P)、1104×621(2K),I want to know why and how to change it!Thank you!

I solved it,The common.yaml:img_downsample_factor changed from 0.5 to 1