Dynamic range is a measure of the range of tones the sensor can capture. Cameras with low dynamic range will often show 'blown' highlights or blocked-in shadows. This test is carried out in controlled conditions using DxO hardware and analysis tools.
Dynamic range is measured in exposure values (EV). The higher the number the wider the range of brightness levels the camera can capture. This falls off with increasing ISO settings because the camera is having to amplify a weaker signal. Raw files capture a higher dynamic range because the image data is unprocessed.
Sony RX100 IV dynamic range charts
JPEG dynamic range analysis: All four cameras turn in a very similar performance in this test, although this time it's the Canon G7 X that comes out on top, narrowly ahead of the Sony RX100 IV.
Raw (converted to TIFF) dynamic range analysis: The raw files tell a different story, however. Here, the Panasonic LX100 displays a remarkably consistent dynamic range across the whole ISO range. The Sony and Canon continue their tit-for-tat battle, each showing a similar reduction in dynamic range at higher ISOs, while the X30 lags slightly behind, as you'd expect given its smaller sensor.