You can save an ImageItem to a file using the following rule and bash script:
rule "HABPanelViewer Picture Taken" when Item ImageItem changed then val outputFile = "/tmp/" + now.toString.replaceAll("[:\\/ \\+]+", "_") + ".jpg" //var String call_result = executeCommandLine("/etc/openhab2/scripts/captureImage.sh ImageItem " + outputFile, 5000) end
with the shell script being:
#!/bin/bash
curl -m 10 --insecure -o - https://openhabianpi:8443/rest/items/$1/state | dd bs=23 skip=1 | base64 -d > $2
Edit: are you using camera API 2 when taking the pictures?