Todd Spangler NY Digital EditorYouTube has supported HDR — high dynamic range, a video format offering a sharper picture, more vibrant colors and higher contrast — since 2016, but until now only for on-demand videos.On Tuesday, it’s launching HDR for YouTube livestreams, making it the first major video platform to support the tech (available to creators who use a compatible encoding setup).By “bringing HDR to live streams, we’re unlocking the most spectacular image quality for live content