The group that sets standards for 4K on high-definition TVs has established specifications for 4K and HDR (high-dynamic range) video on mobile devices including smartphones, tablets and laptops.

Sony is showing off two particularly striking new devices on its stand at this year's Mobile World Congress in Barcelona, Spain, which closes March 2.

HDR up to now hasn’t had a fixed standard. Companies have used the term for marketing reasons, and quality has varied. The UHD Alliance is assuming that the market for 4K video on mobile devices ...