It really depends what embedded system (and display) you have. Most "reputable" embedded system/board vendors in the x86 space are going to offer a firmware cu

It really depends what embedded system (and display) you have. Most "reputable" embedded system/board vendors in the x86 space are going to offer a firmware customization tool, with one of the primary uses being so that you can brand the splash screen at startup. That gets you an image as soon as the firmware brings up the display controller, which should be very fast (i.e. well under a second). YMMV for less supported embedded systems, particularly those with more complicated/proprietary display bringup. Depending on the display in question (assuming you can control the display in use), you may have the ability to configure a splash screen in the display controller itself (the display controller vendor can certainly do this, whether or not they expose it to you is the question). The most complicated (but also most flexible) option is to get whatever the simplest FPGA that can support a HDMI TX and a HDMI RX for the display resolution you desire. Then you build whatever splash screen you want into the FPGA firmware, and whatever boot-finished detection you want to handle the switch from internal splash image to HDMI RX. You'll get the splash screen essentially as soon as your FPGA and HDMI TX power on. If you really know what you're doing, you could even get HDCP passthrough from the embedded system to the display to work here, although you probably can ignore that.