Freescale does not have a specific GStreamer element to do JPEG encoding, so the standard 'jpegenc' should be used.
gst-launch mfw_v4lsrc num-buffers=1 ! jpegenc ! filesink location=sample.jpeg
More pipelines on GStreamer i.MX6 Pipelines
1) How do I get a continuous sequence of images?2) How do I transfer the images through idpsink?