Size of 1080p frame too large

Created by: learnermaxRL

Hi I am trying to extract frames from rtsp stream which streams h264 stream using ffmpeg,each frame size is around 6 mb when read from pipe using image2pipe,however if i save this using mjpeg codec as .jpg file size is in range 0.5 mb,can you tell me a way to continuously pipe 1080p frames of this size using ffmpeg?