Even if you lower the resolution with ROI, the frame rate may not increase depending on your frame rate and exposure time settings.
Note: The exposure time must be set to 1 / (Frame Rate Setting) seconds or less.

How to increase the frame rate when using ROI:

1. Stop image acquisition.
   Go to RemoteDevice -> AcquisitionControl -> AcquisitionFrameRate and set the target frame rate.
2. Go to RemoteDevice -> AcquisitionControl -> ExposureMode, and set it to either OFF or Timed.
   If set to Timed, then:
   Configure RemoteDevice -> AcquisitionControl -> ExposureTime to be 1 / (Frame Rate Setting) seconds or less.
   Set RemoteDevice -> AcquisitionControl -> ExposureAuto to OFF.
3. Restart image acquisition and check the frame rate.

When using ROI, reducing the horizontal resolution will not change the frame rate.
To increase the frame rate, you need to reduce the vertical resolution.